How does the Temperature Converter work?
Temperature is an affine conversion, not a simple factor. Celsius to Fahrenheit: °F = °C × 9/5 + 32, and back: °C = (°F − 32) × 5/9. Kelvin: K = °C + 273.15. Example: 25 °C is 77 °F and 298.15 K.
Background & details
Putting the result in context
Unlike length or weight, temperature has no single multiplier – there is always the offset of 32 or 273.15 on top. That is why "times two" fails as a rule of thumb. For everyday use, fixed anchor points help more than any formula: 0 °C = 32 °F (ice), 37 °C ≈ 98.6 °F (body), 100 °C = 212 °F (boiling water). At −40° the two scales meet: −40 °C = −40 °F.
Which scale for what?
- Celsius is the standard almost everywhere – weather, cooking, medicine.
- Fahrenheit is used mainly in the US: weather, ovens, fever thermometers. A comfortable room temperature there is about 70 °F (21 °C).
- Kelvin is the scientific unit with no negative values; it starts at absolute zero. A difference of 1 K equals 1 °C.
Common mistakes
The classic error is forgetting the offset: 20 °C is not 36 °F but 68 °F. Just as important is the difference between a temperature and a change: if the temperature rises by 10 °C, it rises by 18 °F (only the 1.8 factor, no +32). In baking, many also mix up fan and conventional ovens – but that is not a conversion, it is roughly a 20 °C reduction for fan-forced.
Practical tips
For baking, a quick table helps: 180 °C = 356 °F (standard cake), 200 °C = 392 °F, 220 °C = 428 °F (pizza). US recipes usually round to 350/375/400 °F. For fever: from 38 °C (100.4 °F) it is counted as a raised temperature. Travelling to the US, remember roughly: 60 °F fresh, 75 °F pleasant, 90 °F hot.
Travellers often trip over the air-conditioning display in hotels: if the panel reads 75, in the US it almost always means 75 °F (24 °C) – a comfortable setting. Read it as 75 °C and crank it down in a panic, and you will freeze for no reason. When in doubt, use the anchor rule: anything above 50 is Fahrenheit, because a 50 °C room does not exist.
When a plain conversion is not enough: "feels like" temperature (wind chill, heat index) is not a unit conversion but a separate formula combining temperature with wind or humidity. Likewise, the heating demand of a room depends on differences and insulation, not on the absolute degree figure alone.