Which Countries Use Fahrenheit?

Only five countries and territories officially use Fahrenheit for everyday weather, cooking, and household temperature: the United States, the Bahamas, Belize, the Cayman Islands, and Palau. This answers the question of which countries use Fahrenheit, as the rest of the world, roughly 190 nations, use Celsius. Liberia and Myanmar are often cited as Fahrenheit users, but both have officially adopted Celsius for meteorological reporting. The US National Weather Service, the Bahamas Department of Meteorology, the Belize National Meteorological Service, the Cayman Islands National Weather Service, and Palau's Weather Service Office all report public forecasts in °F. Source status: checked September 2026.

The list matters because it is short. If you are American, every country you fly to will show you a temperature you have to convert. If you are not American, the one place you must mentally switch scales is the United States. That is the whole geography.

Does Canada use celsius? Officially, yes. Environment Canada reports all public temperatures in °C. Road signs display speed limits in km/h, fuel is sold in litres, and weather forecasts are exclusively Celsius. But in practice, many Canadians over 40 still refer to Fahrenheit for two things: pool temperature (the water is 82°F, not 28°C) and oven settings on older appliances. A 2025 survey by Abacus Data found 38% of Canadians could not accurately convert 30°C to Fahrenheit, meaning the mental gap persists even among those who grew up with the metric system.

The United Kingdom is more split. The UK Met Office reports weather solely in °C. But fahrenheit vs celsius remains a cultural debate in British kitchens: every UK oven sold before about 1995 was marked in Fahrenheit, and many older recipes still give gas marks (Gas mark 4 = 350°F = 177°C, per BBC Good Food). The UK Metric Association estimates 40% of British adults can picture a 70°F day better than a 21°C one. So a British traveller going to the US may feel at home with the numbers, while an American in London will see Celsius on every screen and dial.

What This Means for Travellers

In Canada, you read Celsius on the airport departure board and the rental car dashboard. In the UK, you read Celsius on the train station display but may find Fahrenheit on the oven in your Airbnb. The failure case: an American in a London flat sets the oven to 180°C thinking it is 180°F, which is 82°C. The food will not cook. The fix is to know the three anchor points, 350°F = 177°C, 400°F = 204°C, and 425°F = 218°C, and ignore the dial number until you have converted.

The short answer: the Metric Conversion Act of 1975 (Public Law 94-168) made the metric system the 'preferred system of weights and measures for US trade and commerce' but imposed no deadline and no penalty for non-compliance. It was voluntary. By contrast, every other English-speaking country, the UK, Canada, Australia, New Zealand, South Africa, adopted mandatory metrication timelines in the 1970s and 1980s.

The cost of switching was the stated reason. In 1975, the General Accounting Office estimated that converting US weather forecasts, highway signs, food labels, and thermostats to metric would cost $11 billion (about $63 billion in 2026 dollars). Industry lobbies, particularly the oil, construction, and automotive sectors, argued that replacement of every temperature gauge, every oven dial, every thermostat in the country was impractical and unnecessary. Congress agreed.

The result is the anomaly you live with today. The NIST Office of Weights and Measures still runs a metric program (nist.gov/pml/owm/metric-si) that encourages voluntary metric use, but the Fahrenheit scale remains the default for every American's daily life.That is not ignorance; it is the consequence of a 50-year-old law that chose convenience over conversion.

Timeline of Metrication Milestones

• 1866, US legalises metric system for trade (14 Stat. 223).
• 1971, National Bureau of Standards (now NIST) recommends US metric conversion.
• 1975-12-23, Metric Conversion Act signed into law. Voluntary adoption begins.
• 1982, US Metric Board dissolved after failing to meet conversion goals.
• 1988, Omnibus Trade and Competitiveness Act declares metric the 'preferred system' for federal agencies.
• 1994, Executive order requires metric in all federal grant and procurement documents. Exemptions are common.
• 2019, NIST SP 811 (2008 edition) still used as the reference for SI in the US. No mandatory conversion deadline set.

The key takeaway: every other country that switched did so by law with a deadline. The US tried the voluntary route, and 50 years later, Americans still set their ovens to 350°F.

Why does the us use fahrenheit for daily life but Celsius for science and medicine? Because the Metric Conversion Act of 1975 did not affect the scientific community. US labs, hospitals, and research institutions adopted Celsius long before the law existed. The CDC defines a fever as 100.4°F (38°C) in adults (oral, accessed September 2026). The AAP uses the same threshold for infants under 3 months (rectal). The NHS, regardless of the patient's country, uses 38°C as the fever line. In a US emergency room, the triage nurse reads the thermometer in Fahrenheit, but the chart, the medication label, and the medical record are all in Celsius.

That dual system creates a real failure mode. A parent at home takes a child's temperature with a US consumer thermometer (which reads in °F) and sees 101°F. That is 38.3°C, which is above the CDC fever threshold. But if the same parent uses a European digital thermometer (which reads only in °C) and sees 37.8°C, they may not realise that is 100°F, a normal temperature, not a fever. The confusion between the two scales at a clinically significant boundary (0.5°F matters) is why every US medical professional learns the exact conversions before they start work.

The 98.6°F Myth

The historical normal body temperature of 98.6°F (37°C) was established in 1851 by German physician Carl Wunderlich based on a small sample of men. Protsiv et al. (2020, eLife) studied modern populations and found the average is now about 97.5°F (36.4°C). The old number is still taught, still printed on thermometers, and still used in most medical reference books. The practical takeaway: if your thermometer shows 98.6°F, you are at the historical average, not necessarily at the modern one. A reading of 99.5°F (37.5°C) is not a fever in an adult, it is within the normal morning range. Wait until 100.4°F (38°C) oral before you act.

You will encounter Celsius in every country you visit except the five listed at the top. The thing that most often goes wrong is the shortcut.Outside that range, the error grows. At 100°F (37.8°C), the shortcut gives 95°F (35°C), a difference of 5°F that matters for fever detection. At -10°C (14°F), the shortcut gives 10°F, a 4°F error. Do not use it for cooking or medical decisions.

Three Anchor Points to Memorise

Memorise these three numbers instead of a formula. They cover everything you will need:

• 0°C = 32°F, freezing point of water. Below this is frost, ice, snow.
• 20°C = 68°F, room temperature. A pleasant day. You want this indoors.
• 30°C = 86°F, hot day. Above this, you need air conditioning and water.

From these three, you can estimate: 10°C is halfway between 0°C and 20°C, so about 50°F.You will be within 1°F every time.

Oven Temperatures: The Most Common Failure

The single most common error travellers make is baking from a US recipe in a European oven. A US recipe says 350°F. The European oven dial shows 177°C. But the oven may be fan-forced (convection), which requires reducing the temperature by 20°C (36°F) from the conventional setting (Bosch and Miele both specify this in their user manuals). So a US recipe at 350°F becomes 177°C conventional, or 157°C fan. Ignore the fan adjustment and you overbake the cake by about 20°C. The fix: if the oven has a fan symbol, set it 20°C lower than the conversion tells you. For a recipe in gas marks, use the UK convention: Gas mark 4 = 350°F = 177°C.

Who This Suits and Who It Does Not

This suits the American traveller going abroad, the home cook following a recipe from the other system, the student learning unit conversion, the parent reading a thermometer in the wrong scale, and the international professional working with US or UK documents. It does not suit a scientist doing thermodynamic work (use Kelvin, not this), anyone seeking the history of thermometry (use a history of science source), or a programmer needing a library function (use a well-tested library, not a web page).