Celsius to Fahrenheit and back with the exact formula: °F = °C x 1.8 + 32
Runs in your browser. Nothing you type is sent anywhere. Checked against sources on 6 Oct 2026.To change Celsius to Fahrenheit, multiply by 1.8 and add 32: 20 °C is 68 °F and 37 °C, normal body temperature, is 98.6 °F. To go back, subtract 32 and divide by 1.8, so 350 °F in an oven is 176.7 °C. The two scales meet at −40. The converter refuses anything below absolute zero, −273.15 °C or −459.67 °F.
| Celsius | Fahrenheit |
|---|---|
| −40 °C | −40 °F |
| −18 °C | −0.4 °F |
| 0 °C | 32 °F |
| 10 °C | 50 °F |
| 20 °C | 68 °F |
| 25 °C | 77 °F |
| 30 °C | 86 °F |
| 37 °C | 98.6 °F |
| 100 °C | 212 °F |
| 180 °C | 356 °F |
| 200 °C | 392 °F |
The page opens on Temperature with Celsius in the first box and Fahrenheit in the second.
Type the Celsius figure; Fahrenheit is worked out as you type (x 1.8, then + 32).
Type in the Fahrenheit box to go the other way (- 32, then divide by 1.8).
Read kelvin and Rankine for the same temperature under Every unit.
The Unit Converter changes a number between metric, US and UK units of length, weight, volume, temperature, speed, area, data size and time. Type in either of the two boxes and the other one follows, so there is no button to press and no direction to choose. Under the boxes, the same amount is shown in every other unit of that kind.
Where the numbers come from. Every factor is a legal definition, not a rounded table value. NIST Special Publication 811 (the US Guide for the Use of the SI) defines the inch as exactly 2.54 cm, the foot as 0.3048 m, the mile as 1,609.344 m and the pound as exactly 0.45359237 kg. NIST Handbook 44 defines the US gallon as 231 cubic inches and the cup as 8 fluid ounces. The UK gallon is exactly 4.54609 liters. Temperature uses the SP 811 formulas: °F = °C × 1.8 + 32 and K = °C + 273.15. The Definitions tab lists each unit with its definition.
What this converter does not do: cups to grams for an ingredient (that needs a density; use Cups to Grams), Indian land units such as bigha and guntha (Land Area Converter), feet-and-inches arithmetic, shoe sizes or currency.
The rest of the article, and all 6 questions about Unit Converter, are on the Unit Converter page.
One mile is exactly 1.609344 kilometers, because the international mile is defined as 5,280 feet of 0.3048 meters each, or 1,609.344 meters. To go from kilometers to miles, multiply by 0.621371. A 10-kilometer race is therefore 6.21 miles, and a 26.2-mile marathon is 42.195 kilometers.
A kilogram is 2.20462262 pounds. The avoirdupois pound has been defined since 1959 as exactly 0.45359237 kilograms, and dividing 1 by that number gives the pounds in a kilogram. For a quick estimate, double the kilograms and add 10 percent: 50 kg is about 110 pounds, exactly 110.23.
Multiply the Celsius temperature by 1.8 (or 9/5) and add 32. So 25 °C is 25 x 1.8 + 32 = 77 °F. For Fahrenheit to Celsius, subtract 32 and divide by 1.8: 98.6 °F is 37 °C. Both scales read the same at minus 40 degrees.
Every factor is the exact legal definition published by NIST, the US National Institute of Standards and Technology: Special Publication 811 for the inch, foot, mile, pound and temperature formulas, Handbook 44 for gallons, cups and tablespoons, and NIST's binary-prefix page for KiB and MiB. The Definitions tab lists each unit.
Rates and rules change; check the source before you rely on a figure.
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