Moving Abroad? A Practical Guide to Understanding Local Units of Measurement

By ConvertStuffNow  ·  7 min read

Moving to a new country involves a lot of adjustments. One of the less-discussed ones is the measurement system. You might know the currency and the language, but you'll quickly run into a fog of unfamiliar units — road signs in a scale that feels wrong, weather forecasts that mean nothing, grocery packaging in sizes you can't immediately make sense of.

This guide covers the unit differences that matter most in everyday life when relocating, with country-specific notes on what to expect and how to adapt quickly.

The US to anywhere else (or vice versa)

The most common adjustment is between the US and the rest of the English-speaking world. The US uses Fahrenheit, miles and pounds; most countries that share the English language use Celsius, kilometres and kilograms. Here are the adjustments that will affect you every day:

Temperature: the one that catches people every time

If you've grown up with Fahrenheit and you move to a country with Celsius, "25 degrees" will sound cold until your brain adjusts. It's 77°F — a perfectly warm day. "35 degrees" sounds cooler still, but it's 95°F — a very hot day. Your instincts will lag behind your knowledge for months.

The fastest way to calibrate: memorise a few anchors. Zero is freezing. Ten is cold but not bitter. Twenty is comfortable. Thirty is hot. Forty is dangerously hot. Once those land in your head, you can interpolate the rest.

For Americans moving to metric countries: when someone says it's "30 degrees outside," they mean 86°F. When the weather app says tonight's low is 8°C, that's 46°F — you'll need a jacket.

Speed limits and distances on roads

Speed limits are one of the most important unit differences to get right quickly. Getting confused about whether a sign is in mph or km/h on a public road isn't just inconvenient — it's a safety issue.

Moving from a km/h country to the US or UK: Road signs are in mph. 60 mph is about 97 km/h, not 60 km/h. The highway speed limit of 65 mph is approximately 105 km/h.

Moving from the US or UK to most other countries: Signs are in km/h. A speed limit of 100 km/h is approximately 62 mph — about what you'd expect on a motorway.

The UK is a special case: road signs are in miles, but most other measurements are metric. So you'll see speed limits in mph and distances in miles, but petrol is sold in litres and food is labelled in grams.

Grocery shopping and food packaging

In the US, food packaging uses ounces and pounds for weight and fluid ounces and cups for volume. Most of the world uses grams, kilograms and millilitres.

The conversions you'll reach for most often in a supermarket:

• 1 pound = 454 grams (roughly, half a kilogram)
• 1 ounce = 28 grams
• A standard US can of beans is about 400–425 grams
• 1 US gallon of milk = 3.78 litres
• 1 UK pint of beer = 568 ml (a US pint = 473 ml)

Your mental arithmetic will eventually catch up, but in the early weeks of living somewhere new, having a converter on your phone for the supermarket is genuinely useful.

Fuel: the confusion of litres vs gallons and L/100km vs mpg

Fuel is sold by the litre almost everywhere except the US (which uses gallons) and the UK (which switched to litres for fuel sales but still often uses mpg for car specs).

Fuel economy is reported differently too. The US and UK use miles per gallon (mpg) — higher is better. Most of the world uses litres per 100 km (L/100km) — lower is better.

They're inverses of each other, which means you can't just do a simple unit conversion. A car that does 40 mpg (US) does about 5.9 L/100km. A car rated at 8 L/100km does about 29 mpg (US). The general relationship: divide 235 by the L/100km figure to get approximate mpg (US).

Body measurements: height and weight

Americans describe height in feet and inches (e.g. "six foot two"). Most of the world uses centimetres or metres. Six foot two is 188 cm. Five foot eight is about 173 cm.

The UK is mixed: people often know their height in both feet and centimetres, but body weight is commonly given in stone and pounds (see our separate article on the stone). Americans use pounds; most metric countries use kilograms.

For medical appointments in a new country, be prepared to give your height in centimetres and weight in kilograms — even if that requires a quick conversion from the figures in your head.

Clothing and shoe sizes: a different kind of unit problem

Clothing and shoe sizes aren't really a "units" issue in the traditional sense, but they're one of the most confusing adjustments when moving countries. A US size 8 shoe is not the same as a UK size 8, which is not the same as a European size 42. Women's clothing sizes vary dramatically between the US, UK and Europe.

This is outside the scope of unit converters, but it's worth flagging as part of the broader adjustment process. Most international retailers now include size guides with multiple regional scales on their product pages.

The fastest way to adapt

The two strategies that work best are: (1) memorise three or four anchors in the new system and interpolate from there, and (2) use a unit converter for anything where precision matters, until the new system becomes intuitive.

For temperature, the anchors are 0 (freezing), 20 (comfortable), 37 (body) and 100 (boiling). For speed, if you're switching from km/h to mph, remember that 100 km/h ≈ 62 mph and scale from there. For weight, 1 kg ≈ 2.2 lb is the most useful single conversion to have in your head.

Within a few months of daily exposure, most people find the new units start to feel natural. The metric system in particular tends to feel logical once you're immersed in it — the decimal relationships between units are genuinely easier to work with than the patchwork of Imperial conversions.

Conversion values and country-specific unit usage described in this article are accurate as of 2026. Local regulations and conventions may vary.