A Travel Price Comparison for Germany Frankfurt vs. Bonn for Families, Attractions, Food, and Nightlife

Should you visit Frankfurt or Bonn?

Which is cheaper to visit? Which is more expensive for vacation?

Which city is more affordable and which is best for your travel style? If you're trying to figure out where to go next, comparing the travel costs between Frankfurt and Bonn can help you decide which place is right for you.

Frankfurt

Frankfurt is a energetic, dynamic, and diverse city. It's a large city with plenty of activites for visitors as well. Other reasons to visit include museums, nightlife, and food.

Bonn

Bonn is a cultural, beautiful, and outdoorsy city. As this is a very quaint destination, you'll find it has a special atmosphere. It's also popular because of the food, shopping, and museums.

Frankfurt and Bonn: Pros and Cons

Pros
  • Popular museums and historical sights
  • Active nightlife
  • Family-friendly
  • Good for couples and romance
  • Good for backpackers and budget travelers
  • Big city activities
Pros
  • Popular museums and historical sights
  • Active nightlife
  • Family-friendly
  • Good for couples and romance
  • Good for backpackers and budget travelers


Is there more to do in Frankfurt or Bonn?

You'll generally find more things to do in Frankfurt than Bonn. Frankfurt is bigger than Bonn, and it also has more attractions and activities for travelers. Frankfurt is better known for its food, nightlife, and big city activities, while Bonn is more popular for its historical sights and quaint atmosphere. Frankfurt is well known for its financial industry, its popularity as a transportation hub, and its active nightlife. Also, Frankfurt is famous for The Old Town Center. Bonn is well known for its many museums, cultural venues, and university atmosphere, as well as being the birthplace of Beethoven.

The Old Town Center
The Old Town Center

How is Frankfurt different from Bonn?

Which is Better for a Holiday?

Let's take a look at the differences and similarities between Bonn and Frankfurt. Then, you can decide for yourself which place is better for your next trip.

Are the Museums and Historical Sights Better in Frankfurt or Bonn?

Frankfurt
Bonn

You'll find a number of great museums and attractions in both Bonn and Frankfurt.

Many visitors head to Frankfurt specifically to visit some of its top-rated museums and other sights. Many sights are concentrated in the old town center. Highlights include the Historical Museum and St. Nicholas Church. Elsewhere, make sure you check out Maintower, the Städel Museum, and the Museum District.

With a variety of museums, monuments, and historical sights, a trip to Bonn can be an interesting and educational experience. Some of the most popular museums include Haus der Geschichte (history), Beethoven's House, and Kunstmuseum Bonn (art). For architecture check out the Old Town Hall and Bonn Minster. Other landmarks include Poppelsdorf Palace and Schloss Drachenburg.


Is the Food Better in Frankfurt or Bonn? Which Destination has the Best Restaurants?

Frankfurt
Bonn

Frankfurt is a great city for its local flavors and cuisine. Also, Bonn is not as popular, but is still a nice city for its local cuisine and restaurants.

The food selection at local restaurants is excellent in Frankfurt. In addition to a number of international restaurants, the city also has a strong regional cuisine. Some of the most interesting local dishes include Frankfurter Sausage, Rindwurst, Grüne Soße (an herb sauce), and Handkäse mit Musik (marinated sour milk cheese). Also make sure you sample the Apfelwein.

Visitors will find a budding food and restaurant scene in Bonn. Like much of the food in Germany, you'll find local dishes are hearty and filling. Potatoes and meats are popular ingredients, as are milk, butter, and vegetables. For local flavors try the Rhenish Sauerbraten (veal stew), Reibekuchen (German pancakes), or Christmas Sausages.

Is Frankfurt or Bonn Better for Nightlife?

Frankfurt
Bonn

Frankfurt is a great city for nightlife. Also, Bonn is not as popular, but is still a nice city for nightlife and partying.

The nightlife in Frankfurt has something for everybody. It's a vibrant city with many trendy clubs, cocktail bars, music venues, and more. You can enjoy techno, hip hop, and almost any style of music. There are also festivals, beer halls, and classic pubs.

There's a variety of activities in the evening in Bonn. There are bars and nightclubs around town but even more popular are the cultural events that the city hosts. If nightlife is important to you, try to visit during one of the festivals around town.

Is Frankfurt or Bonn Better for its Old Town?

Frankfurt
Bonn

Bonn is an excellent place to visit for its historic old town charm. Also, Frankfurt is not quite as popular, but is fairly good for its historic old town.

There is a nice variety of sights in the old town of Bonn. The old town is filled with cobblestone streets and charming shops. There are also cafes and restaurants where you can grab a bite to eat.

Many visitors go to Frankfurt to see the historical old town. Many museums and cafes are concentrated in the old town area.


Is the Shopping Better in Frankfurt or Bonn?

Frankfurt
Bonn

Shoppers can find a variety of great stores in both Frankfurt and Bonn.

Many visitors explore the shopping areas in Frankfurt. It's a financial capital in Europe, and as such there are plenty of high end shopping opportunities. MyZeil is a major shopping mall in the city and Kleinmarkthalle is a more classic market. Popular shopping neighborhoods and streets include Goethestrasse, Sachsenhausen and Berger Strasse.

Bonn is an extremely popular place for shoppers. A mix of local shops and major chains make shopping fun and easy. Whether you're interested in souvenir gifts or a new outfit, there are countless stores around town.

Is Frankfurt or Bonn Better for Families?

Frankfurt
Bonn

Bonn is an unbeatable place for its kid-friendly activities. Also, Frankfurt is not quite as popular, but is fairly good for its family-friendly activities.

Bonn is one of the most popular family destinations. Just outside of the town is the Haribo factory outlet store where you can pick up a number of sweet treats and spend some time exploring with the kids. Another favorite activity for the whole family is a trip to nearby Phantasialand. This is one of the best amusement parks in Germany and it has many rides for teens and younger kids alike. In town, you'll find playgrounds and kid-friendly museums. Kids will also love a visit to Schloss Drachenburg Castle.

Frankfurt is a very family-friendly place to visit. In town there's a zoo, a children’s museum, a math and technology museum (EXPERIMINTA), and a number of parks, natural areas, and playgrounds. If you're willing to head out of town then you can visit Taunus Wunderland, which is an amusement park with about 50 rides and attractions.

Is Frankfurt or Bonn Better for Couples?

Frankfurt
Bonn

Both Frankfurt and Bonn are notable destinations to visit as a couple.

Frankfurt is a good city for couples to visit. The iconic spot of romance in the city is the Iron Footbridge, which is a traditional spot to attach a "love lock" and take a selfie. The city also offers river cruises, winery tours, and beautiful parks and natural areas.

Bonn is a nice destination for couples. Churches, architecture, and botanical gardens all make this a great couples destination. You can take a cruise down the Rhein or enjoy a meal at one of the best restaurants.


Is Frankfurt or Bonn Better for Backpackers and Budget Travelers?

Frankfurt
Bonn

Frankfurt is a great city for backpackers and budget travelers. Also, Bonn is not as popular, but is still a nice city for backpackers.

Frankfurt is very popular with the backpacker crowd. You'll find a number of hostels in town. The city is also a major transportation hub so many backpackers pass through the area at some point on their trip through Germany.

Bonn is popular with backpackers and budget travelers. Many backpackers skip this town, so its a good option for travelers who want to get off the beaten backpacker trail. There are affordable hotels and hostels around town as well as restaurants where you can pick up something cheap to eat.

Is Frankfurt or Bonn Better for Students?

Frankfurt
Bonn

Frankfurt is very popular for its student-friendly activities. Also, Bonn is not as popular, but is still a nice city for students.

Many students frequent Frankfurt. The city offers prestigious universities and a world class education. The economy offers many internships and job opportunities and you'll find students from around the world studying here. Frankfurt is also well connected to the rest of Europe, so it's easy to explore the region.

Bonn is very popular with students. The city has a very international vibe and you'll likely run into people speaking English around town. Job opportunities in the area are good and there are schools that attract students from around the globe.

Is Frankfurt or Bonn Better for Public Transit? Which Is Easier to Get Around Without a Car?

Frankfurt
Bonn

Frankfurt is very popular for times when you don't have a car. Also, Bonn is not as popular, but is still a nice city for its public transit.

Frankfurt has an effecient and thorough public transportation system which can take you anywhere in the city. It is a huge transportation hub with a major international airport and a number of international train connections. Locally, the city has a subway, trams, commuter trains and buses.

The public transit in Bonn can get you around easily. There is a light rail system that includes 9 lines and 64 stations. There are also buses around town. Bonn is connected to the region by convenient commuter trains so it's possible to visit as a day trip.


Is Frankfurt or Bonn a more walkable city?

Frankfurt
Bonn

Frankfurt and Bonn are great when it comes to walkability.

Frankfurt is a very walkable destination. It has a compact city center that is generally pedestrian-friendly.

Bonn is very walkable. The compact old town is easy to explore on foot.

For even more information, also check out Is Frankfurt Worth Visiting? and Is Bonn Worth Visiting?.

Should I spend more time in Bonn or Frankfurt?

How long in Frankfurt or Bonn?

Visitors can find plenty of fun things to do in both Frankfurt and Bonn. In our opinion, Frankfurt has more to see and do, so we recommend that you spend more time in Frankfurt than Bonn. However, 1-3 days is a good amount of time to spend in either destination.

Families should spend more time in Bonn than Frankfurt. Because of the many family-friendly attractions and fun things to do for kids in Bonn, it's a great place to visit with the whole family.

Couples should spend more time in Frankfurt than Bonn. You'll find plenty of romantic sights and fun activities in Frankfurt that are great for a weekend getaway or a longer couple's trip.

Backpackers and budget travelers should spend more time in Frankfurt than Bonn if your budget allows for it. With a larger number of budget-friendly sights, good nightlife, and active things to do, anyone traveling on a budget would have a good time in Frankfurt.


  • How many days in Frankfurt or Bonn? Ideal Length of Stay
    Frankfurt 1-3 
    Bonn 1-3

One day in Frankfurt or Bonn?

Frankfurt is a big city destination where you can fill many days. Take your pick from the many activities offered here. One day is usually enough time to experience most activities.

You'll find shopping and museums around the city of Bonn. Visiting the old town is also a must. One day is a great amount of time to relax and see the many things that Bonn has to offer. It has many unique tourist attractions and fascinating things to do.

A weekend in Frankfurt or Bonn?

Frankfurt is a fun place to experience. If you have a weekend, this is a great place to go. A weekend is often enough time to do most activities. The entire region has so many activities, and you'll want time to do everything.

You'll find museums and nightlife around the cultural destination of Bonn. The old town is one of the main draws for visitors. This is a popular place to visit for a weekend.A weekend should give you a good understanding of everything this city has to offer. This city offers a variety of activities to choose from.


Five days in Frankfurt or Bonn?

You'll find museums and nightlife around the dynamic big city of Frankfurt. This city offers something for everyone. Five days is plenty of time to see everything, even with extra days to spare.

Travelers enjoy the nightlife and food when visiting the cultural city of Bonn. The length of your ideal trip is an individual decision. Exploring the old town is a popular activity. Five days is plenty of time to see everything, even with extra days to spare.

A week in Frankfurt or Bonn?

The connected city of Frankfurt offers nightlife and food. The length of your trip often depends on your style of travel. One week is usually plenty of time to spend here with extra days to spare. With this much time, visitors often visit nearby destinations or take day trips.

Bonn is a popular choice for travelers. Make sure you visit the old town while you're here. One week is usually plenty of time to spend here with extra days to spare. With this much time, visitors often visit nearby destinations or take day trips. It will give you the chance to have new experiences.


For some great organized tour ideas, see Tours for Outdoor and Nature Lovers in Germany, The Best Oktoberfest Tours in Germany, The Best Coach Bus Tours in Germany, and The Best Adventure Tours to Germany.


Which place is cheaper, Bonn or Frankfurt?

These are the overall average travel costs for the two destinations.

The average daily cost (per person) in Frankfurt is €122, while the average daily cost in Bonn is €154. These costs include accommodation (assuming double occupancy, so the traveler is sharing the room), food, transportation, and entertainment. While every person is different, these costs are an average of past travelers in each destination. What follows is a categorical breakdown of travel costs for Frankfurt and Bonn in more detail.



Accommodation
  • Accommodation Hotel or hostel for one person
    Frankfurt 58
    Bonn 85
  • Accommodation Typical double-occupancy room
    Frankfurt 116
    Bonn 170
Compare Hotels in Frankfurt and Bonn

Looking for a hotel in Frankfurt or Bonn? Prices vary by location, date, season, and the level of luxury. See below for options and compare which is best for your budget and travel style.

Hotels in Frankfurt


Hotels in Bonn


Kayak helps you find the best prices for hotels, flights, and rental cars for destinations around the world. Compare prices for multiple destinations when planning your next trip.


Our Analysis
We've analyzed the average and typical hotel prices based on guest reviews, star ratings, and hotel amenities here: Bonn Hotel Prices.

Local Transportation
  • Local Transportation Taxis, local buses, subway, etc.
    Frankfurt 25
    Bonn 23
Typical Local Transportation Prices in Frankfurt

Here are some examples of typical transportation prices from actual travelers in Frankfurt:


  • Car Rental
    50

Hired Cars and Shuttles in Frankfurt

Also for Frankfurt, here are a few examples of actual transportation services:

  • Private transfer from Frankfurt am Main to Prague: $1,080
  • Transfer from Frankfurt Airport to Munich: $709
  • Transfer from Frankfurt Airport to Baden-Baden: $404
  • Frankfurt Highlights Private Car Tour with Airport Transfers: $390
  • Private Transfer: Frankfurt to River Cruise Dock Nuremberg Port/Harbor transport: $287
  • Private Transfer from/to Frankfurt Airport: $194
  • Private transfer b/w Frankfurt to Heidelberg: $177
  • Frankfurt Airport (FRA): Private Transfer to Frankfurt: $143
  • Private Transfer from Frankfurt City to Stuttgart City: $141
  • BaronFleet Frankfurt- Arrival & Departure Airport Transfers: $132
  • Frankfurt Airport (FRA) to Frankfurt Round-Trip Private Transfer: $110
  • Frankfurt City to Frankfurt Airport Private Transfer : $87

Hired Cars and Shuttles in Bonn

Also for Bonn, here are a few examples of actual transportation services:

  • Bonn hotels Cologne Bonn Airport (CGN) - Departure Private Transfer: $55

Is it cheaper to fly into Frankfurt or Bonn?

Prices for flights to both Bonn and Frankfurt change regularly based on dates and travel demand. We suggest you find the best prices for your next trip on Kayak, because you can compare the cost of flights across multiple airlines for your prefered dates.





Food
  • Food Meals for one day
    Frankfurt 41
    Bonn 49
Typical Food Prices in Frankfurt

For Frankfurt, here are some examples of average food and meal prices for travelers:


  • Soda
    2.00
  • Bagel Sandwich and Latte
    7.00
  • Ham & Cheese Sandwich and Coffee
    6.00
  • Sandwich and Cola
    7.00

Food Tours and Cooking Classes in Frankfurt

For Frankfurt, here are some samples of tours and activities related to meals and dining experiences:

  • Sharing Plate Food Tour In Frankfurt: $66
  • FOOD TOUR TO 3-4 LOCAL FOODSPOTS: $82
  • Eltz Castle Small-Group Tour from Frankfurt with Dinner: $285
  • Heidelberg and Rhine Valley Day Trip With Wine Tasting and Dinner from Frankfurt: $285
  • "Taste of Private Food Tour: $305

Entertainment
  • Entertainment Entrance tickets, shows, etc.
    Frankfurt 36
    Bonn 34

Tours and Activities in Frankfurt

For Frankfurt, here are a few prices for actual activities, tours, and tickets provided by various companies:

  • 2-Hour Best of Frankfurt Walking Tour (English): $26
  • Atta Dripstone Cave and Braunfels Castle Tour from Frankfurt: $274
  • Brandenburg Scavenger Hunt and Sights Self-Guided Tour: $5.59
  • Breathtaking Pearls of Frankfurt – Walking Tour: $381
  • Breathtaking Pearls of Frankfurt - Walking Tour: $245
  • Cologne & Limburg Full-Day Tour: $289
  • Culinary Frankfurt Walking Tour: $621
  • Discover Frankfurt's Heritage: Self-Guided Audio Tour: $11
  • Discover Frankfurt's Soul: Self-Guided Audio Tour: $11
  • Exciting private city tour of Frankfurt for your group: $166
  • Explore Bird & Marine Wildlife private Boat Tour in English: $109
  • Franfurt Horror Tour: Terror of the White Spider: $21

Tours and Activities in Bonn

Also, here are some specific examples of entertainment, tickets, and activities for Bonn.

  • Autumn tours with a live guide: $21
  • Bonn : Private Walking Tour With A Guide ( Private Tour ): $120
  • Bonn : Private Walking Tour With A Guide ( Private Tour ): $121
  • Bonn Crime-Experience: self-guided crime tour: $43
  • Bonn Exploration Game and City Tour on your Phone: $6.17
  • Bonn Musikerviertel Crime Experience: self-guided crime tour: $43
  • Bonn Private Walking Tour With A Professional Guide: $225
  • Bonn Scavenger Hunt and Best Landmarks Self-Guided Tour: $6.62
  • Bonn Scavenger Hunt and Sights Self-Guided Tour: $11
  • Bonn Self Guided City Walking Tour with Audio Guide: $7.35
  • Bonn Self-Guided Historical Walking Tour: $6.10
  • Bonn Walking Tour (In the footsteps of Ludwig Van Beethoven): $327

Alcohol
  • Alcohol Drinks for one day
    Frankfurt 30
    Bonn 23
Typical Alcohol Prices in Frankfurt

Below are a few samples from actual travelers for alcohol and nightlife costs in Frankfurt:


  • Becks Beer
    2.00

Sample the Local Flavors in Frankfurt

Here are a few nightlife and alcohol tours and activities from local tour providers in Frankfurt:

  • Night Pub Crawl through Alt-Sachsenhausen: $22
  • Weekend Night Pub Crawl through Alt-Sachsenhausen: $35
  • Romantic Road Day Ticket from Frankfurt/Main to Rothenburg incl. Wine tasting: $148
  • Private Wine Tour Grape Escape Rhine Valley from Frankfurt: $253
  • Full Day Private Rhine Valley Wine Tour Experience from Frankfurt: $283
  • Frankfurt Wine Tasting Tour with a Wine Expert: $286
  • Guided Walk Tour With Apple Wine Tasting: $341
  • Bachelor(ette) Party with Pub Crawl: $409
  • Private Premium Pub Crawl Tour: $524
  • Private Rhine Valley tour with river cruise & wine tasting: $762


When we compare the travel costs of actual travelers between Frankfurt and Bonn, we can see that Bonn is more expensive. And not only is Frankfurt much less expensive, but it is actually a significantly cheaper destination. So, traveling to Frankfurt would let you spend less money overall. Or, you could decide to spend more money in Frankfurt and be able to afford a more luxurious travel style by staying in nicer hotels, eating at more expensive restaurants, taking tours, and experiencing more activities. The same level of travel in Bonn would naturally cost you much more money, so you would probably want to keep your budget a little tighter in Bonn than you might in Frankfurt.

If you're trying to decide if either of these two destinations are within your price range, also see Is Frankfurt Expensive? and Is Bonn Expensive?.


Which is Bigger, Frankfurt or Bonn?

Frankfurt has a larger population, and is about 2 times larger than the population of Bonn. When comparing the sizes of Frankfurt and Bonn, keep in mind that a larger population does not always imply the destination has more attractions or better activities. So, always research the type of place that you want to visit along with the activities and attractions that interest you.


When is the best time to visit Frankfurt or Bonn?

Both destinations experience a temperate climate with four distinct seasons. And since both cities are in the northern hemisphere, summer is in July and winter is in January.

Should I visit Frankfurt or Bonn in the Summer?

The summer attracts plenty of travelers to both Frankfurt and Bonn. Most visitors come to Frankfurt for the city activities and the family-friendly experiences during these months. Also, the summer months attract visitors to Bonn because of the family-friendly experiences.

In the summer, Frankfurt is around the same temperature as Bonn. Typically, the summer temperatures in Frankfurt in July average around 19°C (67°F), and Bonn averages at about 19°C (66°F).

In Frankfurt, it's very sunny this time of the year. Frankfurt usually receives more sunshine than Bonn during summer. Frankfurt gets 225 hours of sunny skies, while Bonn receives 191 hours of full sun in the summer.

In July, Frankfurt usually receives less rain than Bonn. Frankfurt gets 63 mm (2.5 in) of rain, while Bonn receives 78 mm (3.1 in) of rain each month for the summer.


  • Summer Average Temperatures July
    Frankfurt 19°C (67°F) 
    Bonn 19°C (66°F)

Should I visit Frankfurt or Bonn in the Autumn?

The autumn brings many poeple to Frankfurt as well as Bonn. The autumn months attract visitors to Frankfurt because of the city's sights and attractions and the shopping scene. Also, the shopping scene are the main draw to Bonn this time of year.

In October, Frankfurt is generally cooler than Bonn. Daily temperatures in Frankfurt average around 11°C (51°F), and Bonn fluctuates around 12°C (53°F).

In the autumn, Frankfurt often gets around the same amount of sunshine as Bonn. Frankfurt gets 103 hours of sunny skies this time of year, while Bonn receives 109 hours of full sun.

Frankfurt usually gets around the same amount of rain in October as Bonn. Frankfurt gets 51 mm (2 in) of rain, while Bonn receives 47 mm (1.9 in) of rain this time of the year.


  • Autumn Average Temperatures October
    Frankfurt 11°C (51°F) 
    Bonn 12°C (53°F)

Should I visit Frankfurt or Bonn in the Winter?

Both Bonn and Frankfurt are popular destinations to visit in the winter with plenty of activities. The museums, the shopping scene, and the cuisine are the main draw to Frankfurt this time of year. Also, many travelers come to Bonn for the museums, the shopping scene, and the cuisine.

Be prepared for some very cold days in Bonn. It's quite cold in Frankfurt in the winter. Frankfurt is much colder than Bonn in the winter. The daily temperature in Frankfurt averages around 1°C (34°F) in January, and Bonn fluctuates around 3°C (37°F).

Frankfurt usually receives less sunshine than Bonn during winter. Frankfurt gets 41 hours of sunny skies, while Bonn receives 45 hours of full sun in the winter.

In January, Frankfurt usually receives less rain than Bonn. Frankfurt gets 44 mm (1.7 in) of rain, while Bonn receives 49 mm (1.9 in) of rain each month for the winter.


  • Winter Average Temperatures January
    Frankfurt 1°C (34°F) 
    Bonn 3°C (37°F)

Should I visit Frankfurt or Bonn in the Spring?

Both Bonn and Frankfurt during the spring are popular places to visit. Many travelers come to Frankfurt for the activities around the city.

In the spring, Frankfurt is around the same temperature as Bonn. Typically, the spring temperatures in Frankfurt in April average around 10°C (50°F), and Bonn averages at about 10°C (50°F).

In the spring, Frankfurt often gets more sunshine than Bonn. Frankfurt gets 163 hours of sunny skies this time of year, while Bonn receives 145 hours of full sun.

Frankfurt usually gets more rain in April than Bonn. Frankfurt gets 52 mm (2 in) of rain, while Bonn receives 48 mm (1.9 in) of rain this time of the year.


  • Spring Average Temperatures April
    Frankfurt 10°C (50°F) 
    Bonn 10°C (50°F)

Typical Weather for Bonn and Frankfurt

Frankfurt Bonn
Temp (°C) Rain (mm) Temp (°C) Rain (mm)
Jan 1°C (34°F) 44 mm (1.7 in) 3°C (37°F) 49 mm (1.9 in)
Feb 3°C (37°F) 40 mm (1.6 in) 4°C (39°F) 36 mm (1.4 in)
Mar 6°C (43°F) 51 mm (2 in) 7°C (44°F) 47 mm (1.8 in)
Apr 10°C (50°F) 52 mm (2 in) 10°C (50°F) 48 mm (1.9 in)
May 14°C (58°F) 61 mm (2.4 in) 14°C (58°F) 67 mm (2.6 in)
Jun 17°C (63°F) 70 mm (2.8 in) 17°C (63°F) 73 mm (2.9 in)
Jul 19°C (67°F) 63 mm (2.5 in) 19°C (66°F) 78 mm (3.1 in)
Aug 19°C (66°F) 65 mm (2.6 in) 19°C (66°F) 68 mm (2.7 in)
Sep 16°C (60°F) 48 mm (1.9 in) 16°C (61°F) 58 mm (2.3 in)
Oct 11°C (51°F) 51 mm (2 in) 12°C (53°F) 47 mm (1.9 in)
Nov 5°C (42°F) 59 mm (2.3 in) 7°C (44°F) 56 mm (2.2 in)
Dec 2°C (36°F) 54 mm (2.1 in) 4°C (39°F) 53 mm (2.1 in)