Celsius to Fahrenheit
Free instant celsius to fahrenheit converter. °F = (°C × 9 / 5) + 32.
Common Celsius to Fahrenheit values
| Celsius (°C) | Fahrenheit (°F) |
|---|---|
| -40 | -40 |
| 0 | 32 |
| 10 | 50 |
| 20 | 68 |
| 25 | 77 |
| 37 | 98.6 |
| 100 | 212 |
| 1000 | 1832 |
Temperature tools
Amazon affiliateAs an Amazon Associate we may earn from qualifying purchases. This does not add cost for you.
How does Celsius to Fahrenheit conversion work?
Type a value in the Celsius (°C) field and the equivalent in Fahrenheit (°F) appears instantly to the right. The math uses the exact formula shown above — no rounding errors, no approximations beyond standard floating-point precision. Use the swap button to flip the units and see the inverse conversion.
Celsius. The metric temperature unit. 0 °C is the freezing point of water; 100 °C is the boiling point at sea level.
Fahrenheit. The temperature unit used in the United States. 32 °F is the freezing point of water; 212 °F is the boiling point at sea level.
⚡ Instant results
No submit button — the result updates as you type. Math runs entirely in your browser, so it’s as fast as your device.
📱 Use on any device
Works in any modern browser — Mac, Windows, Linux, iPhone, Android, tablets. No installation, no signup.
🎯 Accurate conversions
Conversion factors come from the official standard (NIST, BIPM, ISO definitions where applicable). Values are precise to standard floating-point limits.
🎁 Always free, no signup
Free, every time. No account, no email, no “trial” that becomes paid. Ad-supported so you never have to pay.
How it works — the formula
F = C × 9/5 + 32
C = (F − 32) × 5/9
K = C + 273.15
C = K − 273.15Temperature scales are affine, not linear: they have both a slope and an offset because zero on one scale is not zero on another. Celsius and Fahrenheit share a slope ratio of 9:5 and intersect at −40° (where °C = °F). Kelvin uses the same magnitude as Celsius but its zero is absolute zero, the lowest physically possible temperature; the 2019 SI redefinition fixed the Boltzmann constant k = 1.380649 × 10⁻²³ J/K exactly.
Worked examples
- Inputs:
- 37 °C = ? °F
- Output:
- 37 × 9/5 + 32 = 98.6 °F
- Inputs:
- 0 °C, 100 °C → °F
- Output:
- 32 °F and 212 °F (definitions of the Fahrenheit scale)
- Inputs:
- −40 °C = ? °F
- Output:
- −40 °F (the unique fixed point where °C = °F)
Limitations
- Negative kelvin is unphysical — absolute zero (0 K = −273.15 °C) is the floor for ordinary thermodynamic temperature.
- Rankine (°R) is a US-engineering absolute scale (R = F + 459.67) sometimes seen in older HVAC / aerospace work.
- Wind chill, "feels-like" temperatures, and humidity-adjusted indices are NOT pure unit conversions — they are derived metrics with their own formulas.
- Above ~10⁹ K, plasma physics uses electronvolt as a temperature unit (1 eV ≈ 11,605 K) — out of scope for everyday converters.
Conversions are exact rational identities between Celsius/Fahrenheit/Kelvin; trailing-digit differences come from binary floating-point representation only.