Temperature Converter
Convert Celsius, Fahrenheit, Kelvin, Rankine and Réaumur.
25 °C in fahrenheit
77.00 °F
Fahrenheit
77.00 °F
Kelvin
298.15 K
Rankine
536.67 °R
Réaumur
20.00 °Ré
°F = (°C × 9/5) + 32
| °C | °F | Reference |
|---|---|---|
| -40 | -40.0 | Severe cold |
| -20 | -4.0 | Severe cold |
| -10 | 14.0 | |
| 0 | 32.0 | Water freezes |
| 5 | 41.0 | |
| 10 | 50.0 | |
| 15 | 59.0 | |
| 20 | 68.0 | |
| 25 | 77.0 | |
| 30 | 86.0 | |
| 35 | 95.0 | |
| 40 | 104.0 | Extreme heat |
| 45 | 113.0 | Extreme heat |
| °C | °F | Gas mark |
|---|---|---|
| 110 | 230 | 1/4 |
| 120 | 248 | 1/2 |
| 140 | 284 | 1 |
| 150 | 302 | 2 |
| 160 | 320 | 3 |
| 180 | 356 | 4 |
| 190 | 374 | 5 |
| 200 | 392 | 6 |
| 220 | 428 | 7 |
| 230 | 446 | 8 |
| 240 | 464 | 9 |
What does Temperature Converter do?
Convert between all five temperature scales with the formula shown for each conversion. The tool validates against absolute zero, so a physically impossible temperature is flagged rather than silently converted.
How to Use Temperature Converter
- 1Enter a temperatureNegative values are fine above absolute zero.
- 2Choose the scaleThe one your value is in.
- 3Read every other scaleAll update together with the formula shown.
Key Features
- All five scales converted at once
- The exact formula shown for each conversion
- Validation against absolute zero
- Reference points marked: freezing, body temperature, boiling
- Oven temperature table including gas marks
Frequently Asked Questions
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 and add 32. 20 °C is (20 × 1.8) + 32 = 68 °F. For a rough estimate, double and add 30.
Why do temperature conversions need an offset?
Because the scales have different zero points. Celsius sets zero at water’s freezing point, Fahrenheit at a brine mixture, and Kelvin at absolute zero. A ratio alone cannot bridge them.
At what temperature do Celsius and Fahrenheit meet?
−40. It is the only point where the two scales give the same number, because their different slopes and offsets cross exactly there.
What is absolute zero?
0 K, which is −273.15 °C or −459.67 °F — the point where molecular motion reaches its quantum minimum. Nothing can be colder, so the converter rejects values below it.
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