Temperature Conversions
Convert temperature scales — Celsius, Fahrenheit, Kelvin, and Rankine. Free calculators with exact formulas for cooking, weather, science, and HVAC.
4 units · 6 calculators
Temperature scales measure thermal energy but use different zero points and step sizes. Celsius (°C) is tied to water's freezing and boiling points; Fahrenheit (°F) is common in the US; Kelvin (K) is the SI base unit for science; Rankine (°R) appears in some engineering contexts.
Unlike length or weight, temperature conversion requires both multiplication and an offset. For example, °F = (°C × 9/5) + 32. Our calculators apply the correct formula for each pair so you never mix up additive and multiplicative steps.
Weather apps, oven knobs, and lab equipment rarely use the same scale. A 10 °C mistake in cooking is noticeable; in industrial process control it can be a safety issue. Always confirm which scale the device displays before you convert.
Quick temperature calculator
Temperature Calculator
Formulas & rules
- °F = (°C × 9/5) + 32
- °C = (°F − 32) × 5/9
- K = °C + 273.15
- °R = (°F + 459.67) (Rankine, engineering)
Popular temperature conversions
- Celsius to Fahrenheit
- Fahrenheit to Celsius
- Kelvin to Celsius
- Celsius to Kelvin (utility)
- Kelvin to Fahrenheit (utility)
- Rankine to Celsius (utility)
Real-world example
An American recipe calls for baking at 350 °F but your oven dial shows Celsius. Converting gives 177 °C, close enough for most home baking without trial and error.
Common mistakes
- Doubling Celsius to get Fahrenheit (e.g. 20 °C is not 40 °F).
- Forgetting that Kelvin starts at absolute zero — no negative values.
- Using outdated oven calibration when converting recipe temperatures.
All temperature conversions
Temperature units explained
- Celsius (°C) · base unit
- Also: °C, C
- Fahrenheit (°F)
- Also: °F, F
- Kelvin (K)
- Also: K
- Rankine (°R)
- Also: °R, R
Frequently asked questions
- What is the formula for Celsius to Fahrenheit?
- °F = (°C × 9/5) + 32. To convert 25 °C: (25 × 9/5) + 32 = 77 °F.
- Why does Kelvin not use degrees?
- Kelvin is an absolute scale starting at absolute zero. By convention it is written as K, not °K, because it is a SI base unit.