How do I convert Fahrenheit to Celsius?

Subtract 32 from the Fahrenheit value, then multiply by 5/9. For example, 72°F = (72 − 32) × 5/9 = 22.2°C.

What is absolute zero?

Absolute zero is 0 Kelvin, −273.15°C, or −459.67°F. It is the lowest possible temperature where all molecular motion stops.

At what temperature are Fahrenheit and Celsius equal?

Fahrenheit and Celsius are equal at −40 degrees. Both scales read −40 at this point.

Why do Americans use Fahrenheit?

Historical inertia. The U.S. customary system, including Fahrenheit, was inherited from 18th-century Britain. The U.K. and the rest of the Commonwealth officially adopted Celsius in the mid-20th century; the U.S. didn't, despite multiple efforts.

Temperature Converter

Instantly convert temperatures between Fahrenheit, Celsius, and Kelvin. Enter a value in any scale to see the equivalent in all three. Includes a reference table of common temperatures.

Last updated: May 14, 2026

About this calculator

Temperature conversions are one of the most common everyday math needs in a world that splits between two main scales. The United States, Bahamas, Belize, Cayman Islands, and Palau use Fahrenheit; nearly everyone else uses Celsius. Scientific and engineering work uses Kelvin (the SI base unit for temperature), which shares the Celsius scale but starts at absolute zero rather than the freezing point of water.

This converter handles all three scales in any direction. Enter a value in any one and see the equivalent in the others.

The conversion math is straightforward once you know the relationship: Celsius and Kelvin share a one-degree size (1°C step = 1 K step), they're just offset by 273.15. Fahrenheit uses a different step size — 1.8 Fahrenheit degrees per Celsius degree — which is why the conversion formula needs both a multiplication and a shift.

Formula

Fahrenheit ↔ Celsius: C = (F − 32) × 5/9 F = C × 9/5 + 32 Celsius ↔ Kelvin: K = C + 273.15 C = K − 273.15 Fahrenheit ↔ Kelvin: K = (F − 32) × 5/9 + 273.15 F = (K − 273.15) × 9/5 + 32 Common reference points: Absolute zero: −273.15 °C = −459.67 °F = 0 K Water freezes: 0 °C = 32 °F = 273.15 K Room temperature: 22 °C = 72 °F = 295.15 K Body temperature: 37 °C = 98.6 °F = 310.15 K Water boils (1 atm): 100 °C = 212 °F = 373.15 K Fahrenheit/Celsius equal: −40 °C = −40 °F = 233.15 K Quick mental conversions: C to F: double the C and add 30 (rough): 20°C ≈ 70°F F to C: subtract 30, halve: 80°F ≈ 25°C

How to use this calculator

Enter the temperature value in whichever scale you have.
Select the source unit. The converter outputs the equivalent in the other two scales simultaneously.
For negative temperatures, just include the minus sign — the conversion handles it correctly.
Kelvin should never be negative. If your input would produce a negative Kelvin, you're below absolute zero, which is physically impossible.

Worked examples

Recipe conversion

A British recipe calls for a 180°C oven. What does that mean in Fahrenheit? F = 180 × 9/5 + 32 = 324 + 32 = 356°F The closest standard U.S. oven setting is 350°F, which is what most converted recipes use.

Travel weather

Weather app shows tomorrow at 28°C in Lisbon. Is that pack-shorts or pack-a-jacket weather? F = 28 × 9/5 + 32 = 50.4 + 32 = 82.4°F Definitely shorts. A useful mental shortcut: 28°C is the upper limit of "comfortable summer" for most people; above 32°C (90°F) becomes uncomfortable.

When to use this calculator

Use this any time you need to translate between U.S. and metric weather, cooking, science homework, lab data, or industry specs. Cooking is the most common use case for everyday users — international recipes routinely give oven temperatures in Celsius, and U.S. cooks need Fahrenheit.

For scientific work, prefer Kelvin: it's the SI base unit, it avoids negative numbers, and most thermodynamic equations work cleanly only in Kelvin. For body temperature, both medical professionals and the general public typically use Fahrenheit in the U.S. and Celsius elsewhere — normal body temperature is 98.6°F or 37.0°C, with fever generally starting around 100.4°F or 38.0°C.

Common mistakes to avoid

Forgetting the +32 offset when converting C to F. 20°C is not 36°F — it's 68°F.
Using the wrong direction of the 9/5 multiplier. C → F is ×9/5; F → C is ×5/9.
Treating Kelvin like Celsius. They share a step size but Kelvin starts 273.15 lower.
Quoting impossible Kelvin values. Anything below 0 K is physically impossible — sanity-check.
Mixing scales in scientific calculations. Most equations expect Kelvin; using Celsius silently gives wrong answers when temperatures appear in absolute terms.

Frequently Asked Questions

Sources & further reading

SI Brochure — temperature unit (kelvin) — International Bureau of Weights and Measures (BIPM)
NIST temperature reference — U.S. National Institute of Standards and Technology

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Temperature Converter

Instantly convert temperatures between Fahrenheit, Celsius, and Kelvin. Enter a value in any scale to see the equivalent in all three. Includes a reference table of common temperatures.

Inputs

Temperature Value

From Unit (0=F, 1=C, 2=K)

Results

Fahrenheit

72.00 °F

Celsius

22.22 °C

Kelvin

295.37 K

Common Temperature References

Reference	Fahrenheit	Celsius	Kelvin
Absolute Zero	-459.67	-273.15	0
Water Freezes	32	0	273.15
Room Temp	72	22.2	295.4
Body Temp	98.6	37	310.15
Water Boils	212	100	373.15