Which Countries Still Use the Imperial System

I still remember the confusion on my face when the gas station attendant in London told me the price per liter instead of gallon. Or when that doctor in Mexico couldn’t understand why I was panicking about my “high fever” of 99 degrees (Fahrenheit, not Celsius).

After traveling to 67 countries, I’ve learned the hard way that most of the world doesn’t measure things like we do in America.

Let me save you from my mistakes with this complete breakdown of which countries still use the imperial system versus the metric system.

Countries That Still Use the Imperial System

Believe it or not, only three countries in the entire world still primarily use the imperial system:

1. United States
2. Liberia
3. Myanmar (Burma)

💡 Tip: Even in these countries, scientific and medical fields typically use metric. I learned this when my Burmese doctor looked confused at my request for my weight in pounds rather than kilograms.

I found this out the expensive way on a road trip through Liberia in 2020. My rental car was low on gas, and I confidently filled up “2 gallons.” Turns out they meant liters, despite using the imperial system officially.

I ran out of gas 20 miles from the nearest station and needed a costly rescue. Make sure your travel insurance covers roadside assistance in imperial system countries. You can find specialized coverage here.

The Weird Case of the United Kingdom

The UK deserves a special mention because it officially uses the metric system but still clings to imperial measurements in daily life. This creates an absolutely confusing mix that has tripped me up dozens of times.

In the UK you’ll find:

• Distance on road signs in miles
• Beer sold in pints
• Fuel sold in liters
• Weight of people discussed in stones and pounds
• Food labeled in grams and kilograms

While dining in London last year, I ordered an 8 oz steak thinking it would be similar to back home.

It weighed twice what I expected because they were using imperial ounces, not American customary ounces (yes, they’re different). Always clarify measurements when ordering or purchasing in the UK.

Countries Using a Mixed System

Several countries officially use the metric system but still use imperial for specific measurements:

💡 Tip: When buying medicine abroad, always confirm if dosage is per kg or per lb. I accidentally took too much cold medicine in Canada because I calculated based on pounds instead of kilograms.

During my trip to Canada in 2021, I got into a minor car accident because I misjudged a merge distance marked in kilometers.

My travel insurance initially denied my claim because I “failed to adapt to local measurement systems” (buried in the fine print).

Make sure your policy doesn’t have this ridiculous exclusion. Compare comprehensive coverage here.

A Brief History: Why These Three Countries?

You might wonder how only these three countries ended up outside the metric fold. Here’s the quick version:

• United States: Nearly adopted metric in the 1970s but industrial resistance prevented the switch
• Liberia: Historical ties to the US as it was founded by freed American slaves
• Myanmar: Former isolation under military rule prevented standardization with international systems

I learned all this from a museum guide in Liberia who laughed when I asked why they used the same “American” system.

He quickly corrected me that we use the “Liberian” system. Fair point!

Imperial vs. US Customary System

To make matters even more confusing, what Americans call the “imperial system” is actually the “US customary system” which differs from the British imperial system in several ways:

This difference caused me major problems when I was cooking in a London apartment, following an American recipe that called for cups and fluid ounces.

My cake was a disaster because British imperial cups and ounces are different sizes.

Common Measurement Conversions For Travelers

After making every possible unit conversion mistake during my travels, I now keep these handy:

💡 Tip: I keep a simple conversion app on my phone that works offline. Saved me from buying way too much fabric for a custom suit in Thailand when I confused yards with meters.

Temperature: Fahrenheit vs. Celsius

Only the US, Liberia, Myanmar, the Bahamas, and a few Caribbean islands use Fahrenheit for temperature.

This has caused me serious problems when:

• Setting oven temperatures while cooking abroad
• Understanding weather forecasts
• Communicating with doctors about fevers

Quick conversions:

• 32°F = 0°C (freezing)
• 70°F = 21°C (room temperature)
• 98.6°F = 37°C (body temperature)
• 212°F = 100°C (boiling)

Or use these formulas:

• C to F: (°C × 9/5) + 32
• F to C: (°F − 32) × 5/9

I learned how important this is when I developed a fever while traveling in Thailand. The doctor looked alarmed when I said my temperature was 101, thinking I meant Celsius (which would be fatal).

Always specify Fahrenheit or Celsius when discussing temperatures abroad.

Expensive Mistakes: The Mars Climate Orbiter Story

My confusion over imperial vs metric is nothing compared to NASA’s $125 million mistake. In 1999, they lost the Mars Climate Orbiter because one team used metric units while another used imperial units in their calculations.

The spacecraft got too close to Mars and disintegrated because of this simple conversion error.

While traveling in Myanmar in 2018, I nearly had my own costly mistake when filling out an insurance claim form. They asked for my height in feet, but were actually recording in meters.

Had I not caught this error, my claim would have been denied for “providing false information.”

Always double check units on important forms. Find insurance with good customer service for these situations here.

Date Formats Around the World

While not part of the imperial system, date formats also differ globally and can cause massive confusion:

• United States: Month/Day/Year (MM/DD/YYYY)
• Most of Europe, Asia, Africa: Day/Month/Year (DD/MM/YYYY)
• China, Japan, Korea, Iran: Year/Month/Day (YYYY/MM/DD)

💡 Tip: When booking appointments or flights abroad, always write the month name instead of the number to avoid confusion. I missed a tour in Japan because I thought 4/7 meant April 7, but they meant July 4.

Practical Tips for Travelers Between Systems

After making every possible measurement mistake in my travels, here’s my advice:

1. Download a conversion app that works offline
2. Memorize a few personal benchmarks:
   • Your height in centimeters
   • Your weight in kilograms
   • Your normal body temperature in Celsius
3. Learn rough conversions:
   • 1 kilometer ≈ 0.6 miles (for quick mental math)
   • 1 liter ≈ 1 quart (slightly more than a quart)
   • 1 kilogram ≈ 2.2 pounds
4. Use the metric system for medicine everywhere (even in the US)
5. Write out full dates (July 4, 2025 instead of 7/4/25 or 4/7/25)

The Benefits of Going Metric

After struggling with conversions for years, I’ve come to appreciate the metric system’s simplicity:

• Everything is base 10 (unlike 12 inches in a foot, 3 feet in a yard, 1760 yards in a mile)
• Units relate logically (1 cubic centimeter of water = 1 milliliter and weighs 1 gram)
• Scientific notation is easier
• The rest of the world uses it

When I returned to America after living in Europe for two years, I actually found our imperial system frustrating and illogical. Many American travelers I’ve met feel the same way after extended time abroad.

Countries That Recently Switched to Metric

Metric conversion is an ongoing process. These countries have made the switch in recent decades:

• Australia: Completed transition in the 1970s
• Canada: Began in 1970s but still uses imperial for some measurements
• Ireland: Completed most conversion by early 2000s
• Jamaica: Still transitioning in some areas
• South Africa: Completed conversion in 2001
• United Kingdom: Officially metric since 1965 but still uses imperial for some measures

💡 Tip: Even in recently converted countries, older people often still think in imperial. When asking for directions in rural Ireland, an elderly man told me the town was “about 5 miles down the road” but it was actually 5 kilometers.

FAQs About Imperial vs Metric System

Why hasn’t the US switched to the metric system?

The US actually tried in the 1970s with the Metric Conversion Act, but it was voluntary and lacked popular support. The estimated cost of conversion and resistance from industries has prevented further attempts.

Is the imperial system still taught in US schools?

Yes, but most US schools now teach both systems, with emphasis on metric in science classes.

Do international companies use metric even in the US?

Yes, most global companies and scientific organizations use metric regardless of location.

How do imperial system countries handle international trade?

Products for international markets are typically designed and labeled using metric measurements, even if made in the US.

Are there any advantages to the imperial system?

Some argue that certain imperial measurements like feet and inches are more practical for everyday human scale measurements, but this is largely due to familiarity.

Conclusion

After traveling extensively between imperial and metric countries, I’ve learned to be flexible with measurements and always double check what system is being used.

For Americans traveling abroad, I recommend spending some time familiarizing yourself with metric conversions before your trip. It will help you understand everything from weather forecasts to food portions to medicine dosages.

For international travelers coming to the US, be prepared for our stubborn adherence to miles, pounds, and Fahrenheit. It’s just one of our charming quirks.

And remember, even NASA made a $125 million mistake with unit conversions, so don’t be too hard on yourself if you get confused.

Before traveling to countries with different measurement systems, make sure your travel insurance covers mistakes related to measurement confusion (yes, some actually exclude this!). Find comprehensive coverage here.

Safe and accurately measured travels to all!