Temperature Converter
Convert between Celsius, Fahrenheit, and Kelvin. Enter a value in any scale and the other two update instantly. The formula used is shown below the result, so you can verify the math yourself.
Conversion Formulas
- Celsius to Fahrenheit — °F = (°C × 9/5) + 32
- Fahrenheit to Celsius — °C = (°F − 32) × 5/9
- Celsius to Kelvin — K = °C + 273.15
- Kelvin to Celsius — °C = K − 273.15
- Fahrenheit to Kelvin — K = (°F − 32) × 5/9 + 273.15
- Kelvin to Fahrenheit — °F = (K − 273.15) × 9/5 + 32
Common Temperature Reference
- −40° — the point where Celsius and Fahrenheit are equal
- 0°C / 32°F / 273.15 K — water freezes
- 20°C / 68°F — room temperature
- 37°C / 98.6°F — human body temperature
- 100°C / 212°F / 373.15 K — water boils (at sea level)
- −273.15°C / −459.67°F / 0 K — absolute zero
Oven Temperature Conversions
- Very low — 120°C / 250°F / Gas Mark ½
- Low — 150°C / 300°F / Gas Mark 2
- Moderate — 180°C / 350°F / Gas Mark 4
- Moderately hot — 200°C / 400°F / Gas Mark 6
- Hot — 220°C / 425°F / Gas Mark 7
- Very hot — 240°C / 475°F / Gas Mark 9
Oven temperatures vary by appliance. Use these as a starting point and adjust based on your oven's calibration.
Frequently Asked Questions
What is the formula for Celsius to Fahrenheit?
°F = (°C × 9/5) + 32. For example, 25°C × 9/5 = 45, then 45 + 32 = 77°F. To go the other way: °C = (°F − 32) × 5/9.
Why are Celsius and Fahrenheit equal at −40°?
Because the two scales intersect at exactly one point. Setting °C = °F in the formula gives x = (x × 9/5) + 32, which solves to x = −40. So −40°C and −40°F are the same temperature. It is the only temperature where both scales agree.
What is Kelvin used for?
Kelvin is the base unit of temperature in the SI system. It starts at absolute zero (the lowest possible temperature) and has no degree symbol. It is used in science, physics, and engineering. Weather and everyday temperature use Celsius or Fahrenheit.
Can temperature be negative in Kelvin?
No. Kelvin starts at 0 (absolute zero), which equals −273.15°C or −459.67°F. You cannot have negative Kelvin — it is the theoretical lowest possible temperature. Values below 0 in Celsius and Fahrenheit are common, but Kelvin never goes below zero.
How do I convert oven temperatures?
Use the reference table above for common oven settings, or convert the Celsius value to Fahrenheit using the standard formula. Gas Mark is a separate scale used in older UK ovens; it does not convert mathematically, so the table above is the practical way to match them.
Is this calculator free and private?
Yes — completely free, no signup, no limits. All calculations run in your browser. No values you enter are sent to a server or stored.