What is the Fahrenheit to Celsius formula?

°C = (°F − 32) × 5/9. The 32 shifts the scale so both meet at water's freezing point, and the 5/9 ratio rescales Fahrenheit's smaller degrees into Celsius's larger ones.

What is 100°F in Celsius?

100 °F is about 37.78 °C: (100 − 32) × 5/9 = 68 × 5/9 ≈ 37.78. That is just above normal body temperature.

What is a normal body temperature in Celsius?

98.6 °F equals exactly 37 °C — the long-standing average for human body temperature. A reading of 100.4 °F (38 °C) is the usual threshold for a fever.

Is there a quick way to estimate Fahrenheit to Celsius in your head?

Yes: subtract 30 and halve the result. For 70 °F, (70 − 30) ÷ 2 = 20 °C (the exact answer is 21.1 °C). It is rough but within a degree or two for everyday weather.

At what temperature are Fahrenheit and Celsius equal?

−40°. Fahrenheit and Celsius read the same value only at −40, where −40 °F = −40 °C. It is the one crossover point of the two scales.

What is 350°F in Celsius for baking?

350 °F equals about 176.67 °C, usually rounded to 180 °C (gas mark 4) in recipes. It is the standard moderate oven temperature.

Why does the formula subtract 32 instead of starting at zero?

Because the two scales do not share a zero. Water freezes at 0 °C but at 32 °F, so you must remove that 32-degree offset before rescaling the degree size with the 5/9 factor.

Conversion

Fahrenheit to Celsius

Convert °F to °C instantly — type a value and watch it convert live, with the formula, the working shown step by step, Kelvin, and lookup charts for weather, fever, and cooking.

Enter a temperature

°F ↔ °C

Fahrenheit (°F)

= (°F − 32) × 5/9

Celsius (°C)

98.6 °F equals

37°C

Body / fever range

°F

98.6

°C

310.15

Edit either field — the other updates live.

Try a value

No sign-up · Free

The basics

What does the conversion mean?

Fahrenheit and Celsius measure the same thing — how hot something is — on two different rulers. They disagree on two things at once: where zero sits, and how big a degree is. The conversion fixes both. Get past those two ideas and the formula stops being magic.

°F − 32

A different starting point

The two scales line up at water's freezing point, but Fahrenheit calls that 32 while Celsius calls it 0. Subtracting 32 removes that head start before anything else happens.

Water freezes: 32 °F vs 0 °C

× 5/9

A different degree size

Between freezing and boiling, Fahrenheit counts 180 degrees where Celsius counts only 100. Each Celsius degree is bigger, so you scale Fahrenheit's figure down by the ratio 5/9.

180 °F-steps = 100 °C-steps

Method

How to convert °F to °C by hand

Three steps. Subtract, then rescale — the order matters.

1
Subtract 32
Remove the 32-degree offset so both scales start from the same place (water's freezing point).
212 − 32 = 180
2
Multiply by 5
Begin rescaling the degree size — this is the numerator of the 5/9 ratio.
180 × 5 = 900
3
Divide by 9
Finish the rescale. The result is the temperature in Celsius.
900 ÷ 9 = 100 °C

Worked examples

See it on real temperatures

The same three steps work for a freezing morning, a fever, or a hot oven. Switch tabs to watch the arithmetic run on each.

Convert 32 °F to Celsius (the freezing point of water)

Subtract 32: 32 − 32 = 0

Multiply by 5: 0 × 5 = 0

Divide by 9: 0 ÷ 9 = 0

32 °F = 0 °C

Quick chart

Fahrenheit to Celsius lookup table

Looking up “what is X°F in Celsius?” — here it is at a glance. Switch between weather, fever, oven, and round-number ranges. The colored dot marks how hot each reading is.

Everyday weather temperatures, 0 °F to 110 °F.

0 °F

−17.78 °C

5 °F

−15 °C

10 °F

−12.22 °C

15 °F

−9.44 °C

20 °F

−6.67 °C

25 °F

−3.89 °C

30 °F

−1.11 °C

35 °F

1.67 °C

40 °F

4.44 °C

45 °F

7.22 °C

50 °F

10 °C

55 °F

12.78 °C

60 °F

15.56 °C

65 °F

18.33 °C

70 °F

21.11 °C

75 °F

23.89 °C

80 °F

26.67 °C

85 °F

29.44 °C

90 °F

32.22 °C

95 °F

35 °C

100 °F

37.78 °C

105 °F

40.56 °C

110 °F

43.33 °C

Where it shows up

When you actually need this

Three everyday places the °F → °C conversion matters most for people coming from the US.

100.4 °F = 38 °C

Health & fever

Thermometers and medical guidance abroad use Celsius. Knowing the fever threshold in both scales avoids a scary misread.

350 °F ≈ 180 °C

Cooking & baking

US recipes give oven temperatures in Fahrenheit; ovens in most of the world are marked in Celsius or gas marks. Converting keeps the bake right.

72 °F ≈ 22 °C

Travel & weather

A forecast of 22 means a pleasant day, not a cold one. Converting makes a foreign weather report instantly readable.

Reference

Key temperatures, both scales

Anchor points worth memorizing. Values are defined in Celsius and converted to Fahrenheit and Kelvin with the same formulas the tool uses.

Reference

°C

°F

Absolute zeroColdest possible temperature

−273.15

−459.67

Water freezesFreezing / melting point

273.15

Cold winter day

−10

263.15

Refrigerator

39.2

277.15

Room temperature

69.8

294.15

Warm summer day

303.15

Normal body temperature98.6 °F

98.6

310.15

Low-grade fever

100.4

311.15

High fever

104

313.15

Hot bath water

113

318.15

Water boilsAt sea level

100

212

373.15

Oven — slow bake

150

302

423.15

Oven — moderate

180

356

453.15

Oven — hot / roast

220

428

493.15

Worth knowing

Facts and shortcuts worth remembering

A handful of landmarks and tricks that make temperature conversion almost automatic.

−40 °F = −40 °C

The crossover point

There is exactly one temperature where both scales agree. Below it, Fahrenheit is the larger number; above it, Celsius catches up but never equals it again.

(°F − 30) ÷ 2

The mental shortcut

Subtract 30 and halve for a fast estimate. It runs a touch warm, but it lands within a degree or two across normal weather — perfect for a quick read.

0 °C ↔ 100 °C

Freezing and boiling

Celsius is built around water: 0 for freezing, 100 for boiling. In Fahrenheit those same points are an un-round 32 and 212.

°C + 273.15

Kelvin is just shifted Celsius

Kelvin uses Celsius-sized degrees but starts at absolute zero. Add 273.15 to °C to get kelvin — no rescaling needed, which is why scientists prefer it.

1 °C = 1.8 °F

Degrees are not interchangeable

A change of one Celsius degree is a change of 1.8 Fahrenheit degrees. A “5-degree” swing means very different things on each scale.

2 × °C + 30

Reverse the estimate

Going the other way, double the Celsius figure and add 30 for a rough Fahrenheit. It mirrors the subtract-30-and-halve trick.

History

Why two scales exist at all

The awkward 5/9 factor is a leftover from history — two inventors who chose their fixed points differently.

Fahrenheit (1724)

Daniel Gabriel Fahrenheit set 0 at the coldest brine mixture he could make and pinned body temperature near 96. Water's freezing and boiling points landed on the odd values 32 and 212 as a consequence.

Celsius (1742)

Anders Celsius instead anchored his scale to water directly — 0 for freezing and 100 for boiling — giving the clean, decimal-friendly scale now used almost everywhere. The US kept Fahrenheit; hence the conversion.

Common mistakes

Where conversions go wrong

Three slips that produce a wrong answer — easy to avoid once named.

32 then 5/9

Order of operations

Subtract 32 before multiplying by 5/9. Rescaling first and subtracting after gives a different, wrong number.

× 5/9 not × 9/5

Flipping the ratio

Going °F → °C uses 5/9. The 9/5 ratio is for the reverse trip — mixing them up roughly triples the error.

−4 °F = −20 °C

Dropping the minus sign

The formula works for negatives too, but the minus sign must survive every step. A lost sign turns a freezing reading into a warm one.

FAQ

Common questions

Subtract 32 from the Fahrenheit temperature, then multiply by 5 and divide by 9. As one formula: °C = (°F − 32) × 5/9. For example, 98.6 °F → (98.6 − 32) × 5/9 = 37 °C.

Keep going

Related calculators

Guide

Fahrenheit to Celsius: formula & chart

Guide

Common temperature conversions

Keep reading

Enter a temperature