The formula
How to use this chart
This page is built around the reference table below — the Celsius, Fahrenheit and Kelvin values people look up most often, from well below freezing to boiling point — plus the calculator above for any value not already in the table. The table steps through round numbers and a few named reference points (freezing, body temperature, boiling) rather than every integer, since those are the values that actually get looked up — a weather forecast, an oven temperature, a fever reading.
Why three scales at once
Each row is one true temperature expressed in three scales at once, so 20 °C, 68 °F and 293.15 K are the same temperature, not three different ones. Pick whichever scale the number you already have is in, and read across.
Worked example
At the default of 20 °C: Fahrenheit = 68 °F, Kelvin = 293.15 K — the same row shown in the table below.
Reading the result
Oven temperatures are a common source of confusion because recipe conventions differ by country: a US recipe in Fahrenheit and a European one in Celsius are not simply rounded versions of each other — 350 °F is 177 °C, not 175 °C, though the rounding rarely matters for baking.
Conventions vary by region and what people are used to, but a widely used rough guide is: below 10 °C (50 °F) cold, 10–20 °C (50–68 °F) cool, 20–27 °C (68–80 °F) warm, above 27 °C (80 °F) hot.
Kelvin is included for completeness and because it is the scale used in science and by some weather instruments internally — the same 20 °C reading a forecast reports is 293.15 K to a physicist, and having all three side by side makes the relationship concrete.
Celsius, Fahrenheit and Kelvin reference table
| Celsius | Fahrenheit | Kelvin | Reference |
|---|---|---|---|
| −40 °C | −40 °F | 233.15 K | Celsius and Fahrenheit cross here |
| −20 °C | −4 °F | 253.15 K | Severe cold |
| −10 °C | 14 °F | 263.15 K | Hard frost |
| 0 °C | 32 °F | 273.15 K | Water freezes |
| 10 °C | 50 °F | 283.15 K | Cool |
| 15 °C | 59 °F | 288.15 K | Mild |
| 20 °C | 68 °F | 293.15 K | Room temperature |
| 25 °C | 77 °F | 298.15 K | Warm |
| 30 °C | 86 °F | 303.15 K | Hot |
| 37 °C | 98.6 °F | 310.15 K | Body temperature |
| 40 °C | 104 °F | 313.15 K | Heatwave |
| 100 °C | 212 °F | 373.15 K | Water boils (sea level) |