Fahrenheit ↔ Celsius Converter
Convert between Fahrenheit (°F) and Celsius (°C) instantly — both ways. Type in either box and the other updates live, with bonus conversions to Kelvin, Rankine and Réaumur, plus a live dual-scale thermometer.
Type a value in either box — the other converts automatically. Negative values are allowed.
Controls how the converted values are rounded.
| Scale | Value |
|---|---|
| Convert to see all scales | |
How to use the Fahrenheit to Celsius converter
Type into either box and the other updates as you go — Fahrenheit to Celsius or Celsius back to Fahrenheit, with Kelvin, Rankine and four historical scales alongside, a live dual-scale thermometer, and a report you can download.
Type into either box
Enter °F or °C — whichever you’ve been given. The other converts live, and negative values are fine.
Set the decimal places
Auto rounds sensibly. Fix it at 0 or 1 for weather and cooking, where a tenth of a degree means nothing.
See where it sits
The position bars place your temperature on the weather range, the freeze-to-boil range, and the comfort range.
Read the thermometer & save a PDF
One column, °F on the left and °C on the right, with freezing and boiling always marked. Eight scales download with it.
How the conversion is calculated
Most unit conversions are a single multiplication. Temperature isn’t, because the two scales disagree about two things at once: where zero sits, and how big a degree is. Fahrenheit puts freezing at 32 and divides the gap to boiling into 180 degrees; Celsius puts freezing at 0 and divides the same gap into 100.
Worked example — a thermostat set to 72 °F
Subtract the offset: 72 − 32 = 40
Scale the degrees: 40 × 5/9 = 22.2 °C
The quick estimate: (72 − 30) ÷ 2 = 21 — about a degree low
Now nudge it up 4 °F: that’s a rise of 4 × 5/9 = 2.2 °C, not −15.6
The 32 belongs to the reading, never to the change. Run a difference through the full formula and the answer comes out nonsense.
Fahrenheit and Celsius conversion charts
The lookups that come up most — everyday temperatures both ways, oven settings with gas marks and fan equivalents, body temperature thresholds, and the landmarks worth memorising.
| Fahrenheit | Celsius | Kelvin | What it feels like |
|---|---|---|---|
| −40 °F | −40.0 °C | 233.2 K | Extreme cold |
| 0 °F | −17.8 °C | 255.4 K | Home freezer |
| 20 °F | −6.7 °C | 266.5 K | Hard frost |
| 32 °F | 0.0 °C | 273.2 K | Water freezes |
| 40 °F | 4.4 °C | 277.6 K | Cold, refrigerator |
| 50 °F | 10.0 °C | 283.2 K | Chilly, jacket weather |
| 60 °F | 15.6 °C | 288.7 K | Mild |
| 68 °F | 20.0 °C | 293.2 K | Room temperature |
| 72 °F | 22.2 °C | 295.4 K | Comfortable indoors |
| 80 °F | 26.7 °C | 299.8 K | Warm |
| 90 °F | 32.2 °C | 305.4 K | Hot |
| 98.6 °F | 37.0 °C | 310.2 K | Traditional body temperature |
| 100 °F | 37.8 °C | 310.9 K | Very hot |
| 110 °F | 43.3 °C | 316.5 K | Dangerous heat |
| 212 °F | 100.0 °C | 373.2 K | Water boils |
Two coincidences worth keeping: 0 °F is almost exactly the standard home freezer setting of −18 °C, and 50 °F is exactly 10 °C — the one point where the “subtract 30 and halve” shortcut gives the right answer.
| Celsius | Fahrenheit | Kelvin | What it feels like |
|---|---|---|---|
| −40 °C | −40.0 °F | 233.2 K | Extreme cold |
| −20 °C | −4.0 °F | 253.2 K | Deep winter |
| −10 °C | 14.0 °F | 263.2 K | Freezing hard |
| 0 °C | 32.0 °F | 273.2 K | Water freezes |
| 5 °C | 41.0 °F | 278.2 K | Cold |
| 10 °C | 50.0 °F | 283.2 K | Chilly |
| 15 °C | 59.0 °F | 288.2 K | Mild |
| 20 °C | 68.0 °F | 293.2 K | Room temperature |
| 25 °C | 77.0 °F | 298.2 K | Pleasantly warm |
| 30 °C | 86.0 °F | 303.2 K | Hot |
| 35 °C | 95.0 °F | 308.2 K | Very hot |
| 40 °C | 104.0 °F | 313.2 K | Dangerous heat |
| 100 °C | 212.0 °F | 373.2 K | Water boils |
Round Celsius values give clean Fahrenheit answers because 5 °C is exactly 9 °F. Round Fahrenheit values rarely return the favour, which is why the table above needs decimals and this one doesn’t.
| Fahrenheit | Exact Celsius | Dial setting | Fan / convection | Gas mark |
|---|---|---|---|---|
| 250 °F | 121.1 °C | 130 °C | 110 °C | Gas ½ |
| 275 °F | 135.0 °C | 140 °C | 120 °C | Gas 1 |
| 300 °F | 148.9 °C | 150 °C | 130 °C | Gas 2 |
| 325 °F | 162.8 °C | 170 °C | 150 °C | Gas 3 |
| 350 °F | 176.7 °C | 180 °C | 160 °C | Gas 4 |
| 375 °F | 190.6 °C | 190 °C | 170 °C | Gas 5 |
| 400 °F | 204.4 °C | 200 °C | 180 °C | Gas 6 |
| 425 °F | 218.3 °C | 220 °C | 200 °C | Gas 7 |
| 450 °F | 232.2 °C | 230 °C | 210 °C | Gas 8 |
| 475 °F | 246.1 °C | 240 °C | 220 °C | Gas 9 |
Dial settings are the conventional rounded equivalents, not the exact conversion — no oven dial has a 176.7 mark. Fan figures follow the usual rule of dropping 20 °C, though manufacturers vary, so check your manual.
| Reading | Fahrenheit | Celsius | Usually described as |
|---|---|---|---|
| Low | 95.0 °F | 35.0 °C | Hypothermia threshold |
| Low-normal | 97.0 °F | 36.1 °C | Within normal range |
| Traditional normal | 98.6 °F | 37.0 °C | The classic figure |
| Upper normal | 99.5 °F | 37.5 °C | Raised temperature |
| Fever threshold | 100.4 °F | 38.0 °C | Fever |
| High | 103.0 °F | 39.4 °C | High fever |
| Very high | 104.0 °F | 40.0 °C | Seek medical advice |
These are unit conversions with the labels commonly attached to them, not medical guidance. Normal temperature varies by person, time of day, age and measurement site, and thresholds differ for infants — follow your thermometer’s instructions and speak to a clinician about what a reading means.
| Point | Fahrenheit | Celsius | Kelvin | Rankine |
|---|---|---|---|---|
| Absolute zero | −459.67 °F | −273.15 °C | 0 K | 0 °R |
| The scales meet | −40 °F | −40 °C | 233.15 K | 419.67 °R |
| Home freezer | 0 °F | −17.8 °C | 255.4 K | 459.67 °R |
| Water freezes | 32 °F | 0 °C | 273.15 K | 491.67 °R |
| Refrigerator | 40 °F | 4.4 °C | 277.6 K | 499.67 °R |
| Room temperature | 68 °F | 20 °C | 293.15 K | 527.67 °R |
| Body temperature | 98.6 °F | 37 °C | 310.15 K | 558.27 °R |
| Water boils | 212 °F | 100 °C | 373.15 K | 671.67 °R |
Boiling point is quoted at sea level. It falls with altitude — roughly a degree Celsius for every 300 metres — which is why high-altitude recipes need longer cooking times.
Converting metres to feet takes one multiplication because both start at zero. Fahrenheit and Celsius don’t: their zeros sit 32 degrees apart, and a Fahrenheit degree is 1.8 times smaller. Two differences means two operations, and doing them in the wrong order gives the wrong answer.
- Subtract before you scale — going from °F, take off the 32 first. Going to °F, scale first and add 32 last.
- A change ignores the offset — a temperature rise or fall converts with 5/9 alone, because the two zeros cancel out of the subtraction.
- Kelvin and Rankine fix the zero — both start at absolute zero, so they never go negative and Kelvin takes no degree symbol.
Everything the converter works out
One figure in either box gives you the full picture — every temperature scale in use and several that aren’t, a thermometer you can read at a glance, and a report you can keep.
The figures behind every temperature
Built for anyone reading the other scale
Almost every country reports weather in Celsius; the United States reports it in Fahrenheit. Recipes, forecasts, thermostats and lab work all cross that line constantly.
Reading a forecast in the scale you didn’t grow up with, packing for a trip, or setting a hotel thermostat that only speaks the other language.
- 20 °C is 68 °F — a comfortable day
- 30 °C is 86 °F — properly hot
- Double and add 30 for a rough °F
Following an American recipe on a European oven, or a metric one on a US range — where gas marks and fan settings add two more scales to the problem.
- 350 °F is 180 °C, gas mark 4
- Fan ovens: drop 20 °C
- Use an oven thermometer to check
Working through thermodynamics or gas law problems where readings arrive in Celsius but the equations need Kelvin, and older papers use Fahrenheit or Rankine.
- K = °C + 273.15, always
- Gas laws need absolute temperature
- Differences convert with 5/9 alone
7 tips for converting temperature without errors
The slips that come from treating temperature like any other unit — and the checks that catch them.
Fahrenheit to Celsius FAQ
The conversion, cooking and body-temperature questions people ask most when a reading arrives in the other scale.
Subtract 32 first, then multiply by 5/9. The order matters, because the two scales differ in where zero sits as well as how big a degree is.
For 72 °F: 72 − 32 = 40, and 40 × 5/9 = 22.2 °C. Going the other way, multiply Celsius by 9/5 and then add 32.
100 °F is 37.8 °C — just above normal body temperature, which is part of why 100 °F feels so oppressive as an air temperature.
The neighbouring round figures are useful too: 90 °F is 32.2 °C, 95 °F is exactly 35 °C, and 104 °F is exactly 40 °C.
350 °F is 176.7 °C, but every oven dial and recipe chart rounds it to 180 °C. That’s gas mark 4, or about 160 °C in a fan or convection oven.
The rounding is harmless because domestic ovens swing by more than a few degrees as the thermostat cycles. An oven thermometer tells you far more than the last decimal of a conversion.
It’s the traditional figure, taken from 19th-century measurements, and it converts to exactly 37 °C. More recent research suggests the average adult runs slightly cooler — nearer 97.5–98.2 °F, or about 36.4–36.8 °C.
Normal temperature also varies through the day, with age, and with where it’s measured. The clinical fever threshold hasn’t moved: 100.4 °F, or 38.0 °C.
At −40. Minus forty Fahrenheit and minus forty Celsius are the same temperature, which is why the figure is often written without a scale at all.
It happens because Fahrenheit runs 1.8 times finer but starts 32 degrees lower. Those two effects cancel at exactly one point, and −40 is it.
The usual clinical threshold is 38.0 °C, which is 100.4 °F. Readings between roughly 37.5 °C and 38 °C are often described as a raised temperature rather than a fever.
Thresholds vary with the measurement method — ear, forehead, oral and underarm readings don’t agree exactly — and guidance differs for infants. Follow the instructions for your thermometer, and speak to a clinician about what a given reading means.
Multiply by 5/9 and skip the 32 entirely. The offset applies to a reading on the scale, not to a gap between two readings.
So a 10 °F rise is a 5.6 °C rise, and a 5 °C drop is a 9 °F drop. Running a difference through the full formula gives a nonsensical answer — it’s one of the most common temperature mistakes there is.
Largely inertia. The US inherited Fahrenheit from Britain, and by the time most of the world had moved to Celsius the scale was embedded in weather reporting, cooking, medicine and everyday habit. Metrication was made voluntary rather than mandatory, so it never took hold for temperature.
A handful of other places also use Fahrenheit for weather, and the UK is genuinely mixed — Celsius official, Fahrenheit still turning up in headlines about hot weather. Science and medicine use Celsius and Kelvin almost everywhere, including in the US.
Reference Conversion Only — Not Medical or Cooking Guidance: This converter changes the temperature you enter between Fahrenheit, Celsius and other scales using the exact formulas °C = (°F − 32) × 5/9 and K = °C + 273.15. It converts readings on a scale; a temperature difference converts with the 5/9 factor alone, without the 32 offset. Body-temperature figures on this page are unit conversions with the labels commonly attached to them, not medical advice — normal ranges and fever thresholds vary by person, age, time of day and measurement method, so follow your thermometer’s instructions and consult a clinician about any reading that concerns you. Oven dial settings, fan equivalents and gas marks are conventional rounded values that differ between manufacturers; check your appliance manual and use an oven thermometer. Boiling and freezing points are quoted at sea level and shift with altitude and pressure. For reference purposes only.