Quick Answer: Celsius to Fahrenheit
0 °C equals 32 °F, and 1 °C equals 33.8 °F (°F = (°C × 9/5) + 32).
Conversely, 1 °F ≈ -17.22 °C.
Formula: °F = (°C × 9/5) + 32
Worked examples
- -40 °C = -40 °F
- -20 °C = -4 °F
- 0 °C = 32 °F
Method and limitations
Multiply by 9/5 (1.8), then add 32: °F = °C × 9/5 + 32. This converts a temperature reading. A temperature difference converts without the offset: Δ°F = Δ°C × 1.8. Calculations use full-precision constants; answers in this box are rounded for readability (≈ marks a rounded value) and the calculator shows up to 9 significant figures. Temperature scales use an offset, not a single multiplier, so this converts a temperature reading. A temperature difference (for example a 10-degree rise) converts with the scale factor only, without the offset.
Each factor is exact by definition, derived from exact definitions, or a documented conventional value — see the methodology and sources.
Conversion Formula
Multiply by 9/5 (1.8), then add 32: °F = °C × 9/5 + 32. This converts a temperature reading. A temperature difference converts without the offset: Δ°F = Δ°C × 1.8.
Complete Guide to Celsius to Fahrenheit Conversion
What is the Celsius scale?
Celsius (°C) puts the freezing and boiling points of water at 0 °C and 100 °C at standard pressure. It is defined from the kelvin: °C = K − 273.15.
What is the Fahrenheit scale?
Fahrenheit (°F) puts the same points at 32 °F and 212 °F, so its degree is smaller: 1 °C of change = 1.8 °F of change.
How the Conversion Works
Scale first (× 1.8) so the degree sizes match, then add 32 to shift zero. −40 °C = −40 °F is a useful self-check.
Step-by-Step Conversion Guide
Follow these steps to convert celsius to fahrenheit manually:
Start with your value in celsius
Example: You want to convert 10 °C
Apply the conversion formula
Use the formula: °F = (°C × 9/5) + 32
Calculate the result
10 °C = 50 °F
Verify your answer
Use our calculator above to double-check your manual calculation.
Quick Mental Math Tip
Double and add 30 for a rough figure: 20 °C ≈ 70 °F (exact 68). The error grows with temperature, so do not use it for oven settings.
Common Conversions
| Celsius (°C) | Fahrenheit (°F) | Fahrenheit → Celsius |
|---|---|---|
| -40 °C | -40 | -40 °F = -40 °C |
| -20 °C | -4 | -20 °F = -28.8889 °C |
| 0 °C | 32 | 0 °F = -17.7778 °C |
| 10 °C | 50 | 10 °F = -12.2222 °C |
| 20 °C | 68 | 20 °F = -6.66667 °C |
| 25 °C | 77 | 25 °F = -3.88889 °C |
| 30 °C | 86 | 30 °F = -1.11111 °C |
| 37 °C | 98.6 | 37 °F = 2.77778 °C |
| 100 °C | 212 | 100 °F = 37.7778 °C |
| 180 °C | 356 | 180 °F = 82.2222 °C |
| 200 °C | 392 | 200 °F = 93.3333 °C |
Popular Celsius to Fahrenheit Conversions
Tap any value to load it into the calculator above.
When You'll Need This Conversion
Metric recipes in a US oven
Turn 200 °C into 392 °F (often rounded to 400 °F on the dial).
Metric weather for US readers
Read a forecast of 30 °C as 86 °F.
Thermostats
Translate a 21 °C setting (69.8 °F) for a Fahrenheit thermostat.
Pro Tips for Accurate Conversions
Readings vs differences
A 2 °C change in a room is a 3.6 °F change, not 35.6 °F.
Common Mistakes to Avoid
Adding 32 before multiplying
(20 + 32) × 1.8 gives 93.6, not 68.
20 × 1.8 + 32 = 68 °F.
Adding 32 to a difference
The offset belongs to readings only.
Δ°F = Δ°C × 1.8.
Frequently Asked Questions
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Conversion factors on this page are either exact by definition, derived from exact definitions, or conventional values in documented use. Each is listed with its source in our conversion methodology and sources, which cites the BIPM SI Brochure, NIST Special Publication 811 and the relevant IEC or national standards. Results are rounded for display only; calculations use full precision.