How this calculator works
The Celsius and Fahrenheit scales are both straight lines, so converting is one multiplication and one addition. Water freezes at 0 °C = 32 °F and boils at 100 °C = 212 °F; those 100 Celsius degrees cover 180 Fahrenheit degrees, so one Celsius degree is 1.8 (9/5) Fahrenheit degrees. Multiply by 1.8, then shift by 32.
To go the other way, take away 32 first and then divide by 1.8. For a rough answer in your head, double the Celsius and add 30 — it is within about 2 °F between 0 and 20 °C, and gets less accurate the further you go.
Assumptions and tips
- The two scales meet at −40: −40 °C = −40 °F.
- Results are exact; the chart rounds to one decimal place.
Worked example
Using the default values in the calculator above:
| Input | Value |
|---|---|
| Convert | Celsius → Fahrenheit |
| Temperature | 25 ° |
| Result | Value |
|---|---|
| Fahrenheit | 77 °F |
| Celsius | 25 °C |
| Kelvin | 298.15 K |
| Quick estimate (double + 30) | 80 °F |
| Feels like | warm room / mild day |
Step by step:
- °F = 25 × 9/5 + 32
- 25 × 1.8 = 45
- 45 + 32 = 77 °F
Celsius to Fahrenheit chart
Common temperatures, converted with this tool. Print the page for a kitchen or classroom chart.
| °C | °F |
|---|---|
| -40 °C | -40 °F |
| -30 °C | -22 °F |
| -20 °C | -4 °F |
| -18 °C | -0.4 °F |
| -10 °C | 14 °F |
| -5 °C | 23 °F |
| 0 °C | 32 °F |
| 5 °C | 41 °F |
| 10 °C | 50 °F |
| 15 °C | 59 °F |
| 18 °C | 64.4 °F |
| 20 °C | 68 °F |
| 21 °C | 69.8 °F |
| 22 °C | 71.6 °F |
| 25 °C | 77 °F |
| 28 °C | 82.4 °F |
| 30 °C | 86 °F |
| 32 °C | 89.6 °F |
| 35 °C | 95 °F |
| 37 °C | 98.6 °F |
| 38 °C | 100.4 °F |
| 40 °C | 104 °F |
| 45 °C | 113 °F |
| 50 °C | 122 °F |
| 60 °C | 140 °F |
| 70 °C | 158 °F |
| 80 °C | 176 °F |
| 90 °C | 194 °F |
| 100 °C | 212 °F |
| 120 °C | 248 °F |
| 150 °C | 302 °F |
| 160 °C | 320 °F |
| 175 °C | 347 °F |
| 180 °C | 356 °F |
| 200 °C | 392 °F |
| 220 °C | 428 °F |
| 230 °C | 446 °F |
| 250 °C | 482 °F |
Common mistakes to avoid
- Adding 32 before multiplying — the order matters: multiply by 1.8 first, then add 32.
- Using the “double and add 30” shortcut for cooking temperatures, where it can be 20°F or more off.
Frequently asked questions
What is 25 °C in Fahrenheit?
77 °F: 25 × 1.8 = 45, plus 32 = 77.
What is 100 °F in Celsius?
37.8 °C: (100 − 32) × 5/9 = 37.78.
What is normal body temperature in Celsius?
98.6 °F is 37 °C.
What is 350 °F in Celsius for an oven?
About 177 °C (most recipes round to 180 °C).
At what temperature are Celsius and Fahrenheit the same?
−40: −40 °C equals −40 °F.
Sources
Built and reviewed by Anirban Kundu, Creator & Editor · M.Sc Physics, 20 years teaching science