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Temperature Converter

Fahrenheit • Celsius • Kelvin • Rankine

Temperature Value ⓘ

From

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Enter a temperature to convert

How to Use the Temperature Converter

Enter a temperature — negative values are valid (e.g. −40°F). Kelvin values below 0 are rejected (absolute zero = 0 K).
Select From unit — Fahrenheit (US everyday use), Celsius (international/scientific), Kelvin (physics), or Rankine (engineering).
Select To unit — your target scale.
Read all four scales at once — °F, °C, K, and °R are all shown simultaneously in the results grid.
Use the gauge — the colored temperature bar shows where your value falls on a −30°C to 110°C reference scale.

Why This Temperature Converter Is Useful

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Travel Ready

Instantly understand weather forecasts abroad — 28°C = 82°F (warm beach day), 10°C = 50°F (cool sweater weather).

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Cooking Precision

European recipes list oven temps in °C. 180°C = 356°F, 200°C = 392°F, 220°C = 428°F.

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Science & Engineering

Shows Kelvin and Rankine for thermodynamics, chemistry, and physics calculations.

Temperature Conversion Guide — Fahrenheit, Celsius, and Kelvin

Temperature conversion is uniquely confusing because it is the only common unit conversion that requires both multiplication AND addition — not a simple ratio. Most conversions (length, weight, volume) use a single multiplication factor, but temperature scales have different zero points: 0°C = 32°F, not 0°F. This is why a simple ratio doesn't work and why many people memorize the key formula: °C = (°F − 32) × 5/9 and °F = (°C × 9/5) + 32.

Critical temperature reference points: Absolute zero = −459.67°F = −273.15°C = 0 K (the coldest possible temperature). Water freezes = 32°F = 0°C = 273.15 K. Human body temperature = 98.6°F = 37°C. Water boils = 212°F = 100°C = 373.15 K. The interesting "crossover" point: −40°F = −40°C (the only temperature identical in both scales).

Quick mental shortcuts: To roughly convert °C to °F in your head: double the Celsius and add 30 (works well between 10°C–30°C). To convert °F to °C: subtract 30 and halve. These are quick estimates — for exact values, use this calculator. Common weather temperatures: 0°C = 32°F (freezing), 10°C = 50°F (cool fall day), 20°C = 68°F (comfortable), 30°C = 86°F (hot summer day), 40°C = 104°F (extreme heat).

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Weather Reference

−10°C = 14°F (cold). 0°C = 32°F (freezing). 10°C = 50°F (cool). 20°C = 68°F (mild). 30°C = 86°F (hot). 38°C = 100°F (very hot). 40°C = 104°F (extreme).

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Oven Temperatures

150°C = 302°F (low). 175°C = 347°F (moderate). 200°C = 392°F (medium-high). 220°C = 428°F (hot). 250°C = 482°F (very hot). Gas Mark 7 = 220°C.

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Body Temperature

Normal: 98.6°F = 37°C. Low-grade fever: 99–100.4°F = 37.2–38°C. Fever: 100.4°F = 38°C. High fever: 103°F = 39.4°C. Dangerous: above 104°F = 40°C.

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Fridge & Freezer

Safe fridge temp: 35–38°F = 1.7–3.3°C. Safe freezer: 0°F = −17.8°C. Food danger zone: 40–140°F = 4.4–60°C. Never thaw at room temp above 40°F = 4.4°C.

Temperature Conversion FAQ

What is the formula to convert Fahrenheit to Celsius? ▾

°C = (°F − 32) × 5/9. Step by step: subtract 32 from the Fahrenheit temperature, then multiply by 5 and divide by 9. Example: 98.6°F → (98.6 − 32) × 5/9 = 66.6 × 0.5556 = 37°C. Common conversions: 32°F = 0°C, 68°F = 20°C, 77°F = 25°C, 86°F = 30°C, 98.6°F = 37°C, 212°F = 100°C.

What is the formula to convert Celsius to Fahrenheit? ▾

°F = (°C × 9/5) + 32. Multiply Celsius by 1.8 and add 32. Example: 37°C → 37 × 1.8 + 32 = 66.6 + 32 = 98.6°F. Quick mental estimate: double Celsius and add 30 (overestimates by 2°F typically). Exact: multiply by 9/5 and add 32.

What temperature is −40°F in Celsius? ▾

−40°F = −40°C. This is the only temperature where Fahrenheit and Celsius are equal. It occurs because the two scales converge at this point: (−40 − 32) × 5/9 = −72 × 0.5556 = −40.0°C. In practical terms, −40°F/°C is an extreme cold experienced in places like northern Canada, Alaska, and Siberia.

How do you convert Celsius to Kelvin? ▾

K = °C + 273.15. Simply add 273.15 to the Celsius temperature. Kelvin is the SI unit of thermodynamic temperature and the zero point (0 K = absolute zero) is the coldest possible temperature where all molecular motion stops. 0°C = 273.15 K. 100°C = 373.15 K. 37°C (body temp) = 310.15 K. Kelvin is never written with a degree symbol — it's 310 K, not 310°K.

Why does the US use Fahrenheit instead of Celsius? ▾

The Fahrenheit scale was developed by Daniel Gabriel Fahrenheit in 1724 and was the dominant temperature scale in English-speaking countries through the 19th century. The US maintained it as part of the broader imperial system while most other countries switched to Celsius (developed by Anders Celsius in 1742) during metrication in the 1970s and 80s. The US weather service, medical community, and everyday culture never made the switch. Interestingly, Fahrenheit does offer a useful 0–100 range for human comfort: 0°F is "very cold outside" and 100°F is "about as hot as a human body can sustain comfortably."