The Countries That Use Two Measurement Systems at Once — and Why It's Chaos

The Only Fully Imperial Holdouts

You have likely heard the trivia claim that only three nations in the world do not use the metric system: the United States, Liberia, and Myanmar.

While the US remains the largest economy using customary imperial units for daily life, the reality in Liberia and Myanmar is rapidly shifting. Both nations have formally pledged metrication efforts in recent years. Furthermore, even inside the United States, key sectors—including medical science, the military, pharmaceuticals, and foreign trade—operate entirely in metric units.

The UK — Miles for Roads, Metric for Everything Else

The United Kingdom presents one of the most intriguing hybrid measurement landscapes in the world.

If you drive through England, road signs and speed limits are exclusively posted in miles and miles per hour (MPH). If you step into a pub, beer and cider are legally served in pints.

Yet if you buy gasoline at a station, it is sold in liters. If you buy groceries at a supermarket, meat and produce are weighed in grams and kilograms. Body weight is colloquially discussed in stones and pounds, while human height is stated in feet and inches. This patchwork leaves citizens fluidly switching between measurement systems multiple times a day!

Canada's Partial Metrication

Canada began an ambitious metrication program in 1970 under the Metric Commission. Today, weather forecasts report in Celsius, road signs use kilometers per hour, and gasoline is sold by the liter.

However, due to Canada's deep trade relationship with the United States, imperial units remain deeply entrenched. Real estate is almost universally priced in square feet, oven temperatures in recipes use Fahrenheit, and personal height and weight are typically stated in feet, inches, and pounds.

As seen in our story on the Gimli Glider flight, operating during a national metric transition period requires strict procedural double-checks to prevent catastrophic errors.

Why Don't These Countries Just Fully Switch?

If the metric system is logically consistent, why do nations maintain hybrid systems?

• Infrastructure Replacement Costs: Replacing millions of metal speed limit signs, highway markers, and vehicle speedometers costs billions of dollars.
• Generational Habits: Cultural memory and idioms ("give them an inch and they'll take a mile") linger for generations after official policy shifts.
• Trade Interdependence: Manufacturers trading heavily with the United States must produce dual-spec goods to serve both domestic and US supply chains.

Quick Reference — System Usage Comparison Table

A comparison of measurement preferences across key English-speaking nations:

Frequently Asked Questions