In an earlier article I wrote about the many little differences in daily culture that can sometimes frustrate expats in German-speaking Europe. I listed 15 “Kleinigkeiten” that may or may not be minor matters – from traffic signal placement to the bare kitchen. But today we’ll discuss a different sort of pesky cultural difference, and how to cope with it.

Updated for 2024.

This almost exclusively concerns US-Amerikaner (as the Germans so accurately say). We US Americans are the last of a dying breed: people who do not use the metric system. The United States of America is one of the few places left on earth where average people still measure things in feet and inches or yards and miles. Americans are also left out in the cold when it comes to measuring temperatures. Almost no one else uses degrees Fahrenheit any more. Even the British have moved on to the Celsius system, although in their muddling way road signs are still in miles and you can still order a pint of beer. Metricizing (metricising) has its limits in the UK.

Buying groceries in Europe means dealing with the metric system.
PHOTO: Hyde Flippo

Metric measure is not a problem for non-Americans moving to Austria, Germany or Switzerland. Even the Canadians went metric back in the 1970s. (It is only commercial and cultural ties to the US that keeps some vestiges of non-metric alive in Canada.) Because metrication never really caught on in the US, we Americans are handicapped when we leave our familiar shores.

So you finally learned your German numbers and you can actually understand a basic weather forecast in German, but how warm or cold is 15 degrees Celsius? How deep is 8 centimeters of snow? After a while, expats learn these things, but what if you want to convert certain measurements for yourself or friends and relatives in the US – without a calculator, computer or smartphone?

Here are seven shortcut methods that allow you to do these conversions in your head. Even a non-math person like me can do it!

1. Celsius (centigrade) to Fahrenheit. Double the Celsius degrees and add 30 (not 32!). This is a surprisingly accurate shortcut that works for average daily temperatures. If it’s 10°C, double that (20) and add 30 = 50°F (actual answer: 50°F!). If it’s 25°C, you double that to 50 and add 30, which gives you 80°F. The precise answer is 77°F. This shortcut also works for minus temperatures: -5°C x 2 = -10 + 30 = 20°F (precise answer: 23°F). – Trivia: Which temperature is identical in Celsius and Fahrenheit? In other words, at which identical number on both temperature scales would you feel exactly as hot or cold? (See answer below.)

2. Kilometers to miles. Use the six-tenths-rule (the 0.6-rule) to get a good ballpark figure for distances or speed. If something is 50 km away, it’s 30 miles away (0.6 x 50 = 30, or multiply by 6 and drop a zero). The precise answer is 31.07 miles (0.621 x 50; one kilometer = 0.621 mi), but our rough figure is pretty close. For longer distances you can get closer by adding a “fudge factor” of 3%. For instance, 500 km multiplied by 0.6 is 300 miles, but you get even closer by adding 3% (9) to get 309 miles. (Actual answer: 310.7 miles.) Even without adding 3%, you come close enough for most situations.

3. Meters to feet. Multiply by 3 and add 10%: 20m x 3 = 60 + 6 = 66 ft (precise answer: 65.6 ft). The Zugspitze, Germany’s tallest mountain, is 2,962 meters above sea level. To get feet, we round off: 3,000 x 3 = 9,000. Add 10% to get 9,900 ft (precise answer: 9,718 ft). For feet to meters, divide by 3, then subtract 10%. Germans are always asking me how high Reno is above sea level. It’s 4,200 ft, so divided by 3 that equals 1,400. Subtract 10% (140) and you get 1,260 meters. (The accurate figure is 1,280 meters.) Of course, I learned long ago what it is in meters, so I just tell them: “Reno liegt ungefähr 1300 Meter über dem Meeresspiegel.” Close enough for government work.

4. Liters to US gallons. Divide liters by 4 (actually 3.785 or 3.8) to get gallons. 40 l / 4 = 10 gal. Actual answer: 10.5 gal. For gallons to liters, multiply by 4 and you’ll be pretty close: 20 gal x 4 = 80 liters (actual: 76 l).

5. Liters to quarts. Remember the old soft-drink slogan “a liter bit more” for the liter bottle, which contains a little bit more than a quart: one liter = 1.05 quarts. Ten liters = ca. 10 quarts.

6. Kilos to pounds. A kilogram (kg, 1000 grams) is 2.2 pounds. Multiply the kilo figure by two: 50 kg x 2 = 100 lb, and add 10%: 110 lbs. That is darn close to the precise answer: 110.2 pounds. To get from pounds to kilos, divide by 2 and subtract 10%: 100 lb / 2 = 50 – 5 = 45 kg (actual figure: 45.35 kg).

7. Centimeters to inches. Computer monitors and TV screens are the only things in Germany still measured in inches (Zoll), so this conversion can be useful. The easiest way is to memorize how many centimeters are in an inch (2.54 cm). So 5 cm = 2 inches, 10 cm = 4 inches, and so on. If there are 8 cm of snow on the ground, how many inches is that? 8 / 2.5 = 3.1 in. On a meter/yardstick you’ll see that 66 cm matches 26 inches. A yard (36 in) is slightly more than 91 centimeters. Most people simply memorize their height in centimeters. A person who is 5 feet, 9 inches tall (69 inches) is 175 cm (175.2 cm). A six-footer (72 in) is 183 cm (182.88 cm) or 1.83 m tall.

Fuel Mileage (MPG)
Here’s where we run out of easy shortcuts, but we do offer our readers some help. One thing I’ve never found a good shortcut for: converting liters per 100 km to miles per (US) gallon, or vice versa. (Sorry, but dividing 235 by a l/100 km-figure is not something I can do in my head! 235 / (8 l / 100 km) = 29.4 mpg.) The reason for the difficulty is that miles per gallon (mpg) and liters per hundred kilometers (l/100 km) don’t really measure the same thing!

This EPA/DOT “Fuel Economy” statement for an Audi A4 displays the “combined city/hwy” in large bold print. The fuel consumption rating of “3.7 gallons per 100 miles” is much less obvious. (Can you find it?) But it is actually the most important rating for car buyers to consider. It uses the same metric found in the German/European “liters per 100 kilometers” rating. PHOTO: Hyde Flippo

Fuel Consumption versus Fuel Economy
The l/100 km figure indicates a rate of fuel consumption, while mpg is a measure of fuel economy (“gas mileage”). One system concentrates on how much fuel you use to cover a certain distance (gallons per mile), while the other (miles per gallon) concentrates on how far you can go per fuel unit. But even the almost universal metric system has no consistent way of measuring fuel consumption/economy. Some countries do actually use the metric equivalent of mpg (km/liter), but Germany isn’t one of them. To fully understand the difference, see this Wikipedia page, which also mentions which countries use which system.

Few Americans know that, beginning with the 2012 model year, the EPA (Environmental Protection Agency) started providing fuel consumption ratings (as opposed to fuel economy) in the “gallons per 100 miles” format. Yes, it’s easy to miss, but when you buy a car in the US the window sticker shows the usual miles-per-gallon (MPG) rating in large print. However, in much smaller print below that you’ll also find the “gallons per 100 miles” rating. You can see the data for my now-traded-in 2019 Audi A4 in the photo above. A lower number is better, and the European goal is the “three-liter” car that scores 3.0 liters/100 km, one that uses no more than 3 liters (about 3 quarts, a quart less than a gallon) of fuel to drive 100 km (62 miles). A three-gallon car (per 100 miles) is rare

There may be no MPG shortcut, but there are online charts and calculators for mpg conversion. For starters, 26 mpg = 9 liters per 100 km (9.05 l for sticklers). The lower the mpg figure, the higher the liters per 100 km figure (6 mpg = 39.2 l per 100 km; 40 mpg = 5.88 l per 100 km). The Dutch, the Japanese and some others use kilometers per liter, closer to our miles per gallon: 26 mpg = 11.05 km/l. Here’s a good conversion table for both km/l and l/100 km.

A web search will also get you charts or calculators for pressure, power, and other conversions that are just too complicated for simple shortcuts. If you know of a good conversion shortcut I haven’t mentioned, please leave a comment.

– HF

Trivia answer for item No. 1: minus 40 degrees, 40 below zero on either scale.