Celsius to Fahrenheit — The Complete Conversion Guide
January 18, 2026 · 6 min read
The formula, a chart of key temperatures, and a mental-math shortcut for converting Celsius to Fahrenheit.
Why this matters
"Celsius to Fahrenheit" is one of the most searched conversions on Google. Whether you're cooking, traveling, or checking the weather, knowing how to switch between the two scales is genuinely useful.
The formula
°F = °C × 9/5 + 32. Reverse: °C = (°F − 32) × 5/9. Kelvin: K = °C + 273.15.
Quick reference chart
−40 °C = −40 °F (the only point they agree). 0 °C = 32 °F (freezing). 10 °C = 50 °F. 20 °C = 68 °F (mild day). 37 °C = 98.6 °F (body temp). 100 °C = 212 °F (boiling).
The mental-math shortcut
Double the Celsius value, subtract about 10%, then add 32. 20 °C → 40 − 4 + 32 = 68 °F. Not perfect, but within a degree for most everyday temperatures.
Kelvin — the third scale
Kelvin starts at absolute zero (−273.15 °C). Used by scientists because it has no negative values. 0 K = no thermal motion at all.
Benchmarks worth knowing
Body temp 37 °C / 98.6 °F. Hot bath 40 °C / 104 °F. Oven baking 180 °C / 356 °F. Hot summer day 35 °C / 95 °F.
Frequently asked questions
What is 37°C in Fahrenheit?
37 °C equals 98.6 °F, the average human body temperature.
At what temperature are Celsius and Fahrenheit the same?
−40°. It's the only point where the two scales cross.
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