Which Countries Still Use Imperial Measurements? A Global Guide to Metric vs Imperial

Walk into a hardware store in London and you’ll find screws measured in millimeters. Drive across the American Midwest and the speed limit signs read in miles per hour. Most of the world has converged on a single system of measurement — but a handful of countries still march to a different beat. So why does the imperial system persist, and who are the last holdouts?

A Brief History of the Metric System

The metric system was born out of the chaos of the French Revolution. In the 1790s, French scientists and lawmakers sought a universal, rational system of measurement to replace the patchwork of local units that varied from town to town. The result was the Système International d’Unités — the SI system — built on base units like the metre, kilogram, and second.

Over the 19th and 20th centuries, metrication spread rapidly. International trade, scientific collaboration, and colonial influence all accelerated adoption. By the mid-20th century, the metric system had become the global standard for science, medicine, and commerce. Today, the history of the metric system is a story of remarkable consensus — one that almost every nation on Earth has joined.

Which Countries Still Use Imperial?

As of today, only three countries have not officially adopted the metric system as their primary standard: the United States, Liberia, and Myanmar (also known as Burma). That said, the picture is more nuanced than a simple list suggests. For a deeper look at global metrication progress, see the Metrication article on Wikipedia.

The United States

The US is by far the most prominent imperial holdout — and its resistance to metrication is a fascinating case study in cultural inertia. The country came close to switching in the 1970s: the Metric Conversion Act of 1975 established a national policy to transition to metric, but it was voluntary, underfunded, and ultimately ignored by most of the public.

Today, Americans live in a hybrid world. Scientists, doctors, and the military routinely use metric. Pharmaceutical doses are in milligrams. Nutrition labels list grams. Yet everyday life remains stubbornly imperial: distances are measured in miles, body weight in pounds, temperatures in Fahrenheit, and beverages in fluid ounces. The cost of converting road signs, consumer packaging, and public infrastructure — combined with deep cultural familiarity — has kept the imperial system firmly entrenched.

Liberia and Myanmar

Liberia and Myanmar are often cited alongside the US, but both countries have made meaningful moves toward metric in recent decades. Myanmar announced plans to adopt the metric system for trade and commerce, and metric units are increasingly used in official contexts. Liberia, similarly, uses metric in many professional and governmental settings, even if traditional local units persist in daily life. Neither country is as deeply committed to imperial as the United States.

Why the Rest of the World Went Metric

The case for metric is compelling. A decimal-based system is simply easier to work with: converting kilometers to meters requires only moving a decimal point, while converting miles to yards to feet to inches demands memorizing arbitrary multipliers. For scientific research, a shared standard eliminates costly errors — famously, NASA lost the Mars Climate Orbiter in 1999 partly due to a metric-imperial unit mismatch.

For international trade, metric provides a common language that reduces friction and mistakes. For education, a logical, consistent system is far easier to teach. These advantages explain why nation after nation — from the British Empire to post-colonial Africa and Asia — chose to standardize on metric as they modernized their economies.

Metric vs Imperial in Everyday Life

For travellers moving between metric and imperial countries, a few quick mental shortcuts go a long way:

• Distance: 1 mile ≈ 1.6 kilometers (or roughly 8 km = 5 miles)
• Weight: 1 kilogram ≈ 2.2 pounds; 1 pound ≈ 454 grams
• Temperature: To convert Celsius to Fahrenheit, multiply by 1.8 and add 32
• Volume: 1 litre ≈ 0.26 US gallons

If you need to convert weights quickly, our weight conversion guide walks you through the most common conversions step by step. For land and property measurements, check out our area conversion guide. And if you’re puzzling over a weather forecast in an unfamiliar unit, our Celsius to Fahrenheit guide has you covered.

Will the US Ever Go Metric?

The debate resurfaces periodically in American public life. Advocates point out that US industries competing globally — pharmaceuticals, aerospace, automotive manufacturing — already operate in metric. The US military uses metric for ammunition and equipment. American scientists publish exclusively in SI units.

Yet a full public switch remains politically and logistically daunting. Replacing road signs alone would cost billions of dollars. Consumer habits, cookbooks, construction standards, and decades of institutional memory all reinforce the status quo. Some optimists argue that gradual, sector-by-sector adoption is already happening organically. Others believe only a legislative mandate could complete the transition — and there’s little political appetite for that fight.

For now, the United States occupies a curious middle ground: a metric nation in its laboratories and a imperial nation in its daily life.

Understanding the difference between metric and imperial isn’t just a history lesson — it’s a practical skill for anyone who travels, shops internationally, or works across borders. Ready to convert? Use our free length and distance converter to switch between metric and imperial instantly.