💱 Fahrenheit to Celsius Converter - F to C Calculator

Instantly convert Fahrenheit to Celsius with exact arithmetic, view the formula, and get Kelvin values. No sign‑up, no rounding until the final step.

Last updated: 19 October 2026

Fahrenheit to Celsius Converter: Convert F to C Instantly

This free fahrenheit to celsius calculator turns any Fahrenheit reading into Celsius with exact arithmetic, shows the fahrenheit to celsius formula with your own number substituted, and converts back the other way too. Type a value, pick the direction, and read the result, the steps, and a chart — no sign-up, no rounding before the final step.

Quick answer: to convert fahrenheit to celsius, subtract 32 and multiply by 5/9. So 72 °F = 22.2 °C, 98.6 °F = 37 °C and 350 °F = 176.7 °C. This page is a temperature converter for units only — it gives no medical, weather or cooking advice.

F to C calculator

Direction

Enter a number. Whole numbers and decimals both work.

Result

Enter a temperature to convert.

What this tool does not do: it does not diagnose fever, forecast weather, recommend cooking times, interpret heat index or wind chill, or calibrate instruments. It converts units only.

Status: exact arithmetic

Saving stores only the number, direction and decimals in this browser. Nothing is sent anywhere.

Method & sources

  • Rule / formula version: FC-2026-10-19 (stored inside this page's script file).
  • Last updated: 2026-10-19.
  • Reference starting points to check yourself: NIST Office of Weights and Measures — https://www.nist.gov/pml/owm ; NIST SP 811, Guide for the Use of the International System of Units — https://www.nist.gov/pml/special-publication-811 .
  • Arithmetic: exact integer-scaled decimal math (BigInt), rounded half up only at display. No binary floating point is used for displayed results.
  • The formulas are standard definitions, but no primary source was retrieved, so treat this page as unverified until a NIST page is checked.

How to use this Fahrenheit to Celsius converter

  1. Choose the direction: Fahrenheit to Celsius (F to C) or Celsius to Fahrenheit (C to F). The Swap direction button flips them in one click.
  2. Type the temperature in the input box. The label always tells you which unit the number is in, so a quick f to c check takes a couple of seconds.
  3. Pick how many decimals you want (1 to 4, default 1).
  4. Read the result, the substituted formula, and — if you ticked it — the Kelvin value. The reference chart below updates with the same engine.

Everything runs in your browser. Identical inputs always give identical output, because the arithmetic is exact and the display rounding happens only at the end.

Fahrenheit to Celsius formula: how to convert Fahrenheit to Celsius in three steps

Here is how to convert fahrenheit to celsius by hand:

  1. Subtract 32 from the Fahrenheit reading (the freezing point of water is 32 °F).
  2. Multiply by 5.
  3. Divide by 9.

°C = (°F − 32) × 5 ÷ 9  ·  the reverse rule is °F = °C × 9 ÷ 5 + 32  ·  K = °C + 273.15

The reverse direction is just the algebra solved the other way: a celsius to fahrenheit conversion multiplies by 9/5 and adds 32. The tool keeps full precision internally (for example 72 °F is exactly 200/9 °C, a repeating decimal) and rounds only when it prints.

Worked examples

Each example below is computed by the same engine that runs the calculator. Repeating decimals are shown with the selected precision and marked as repeating.

Worked fahrenheit to celsius examples with the full substitution
InputSubstitutionResultNote
32 °F(32 − 32) × 5 ÷ 90 °CWater freezes at standard pressure.
212 °F(212 − 32) × 5 ÷ 9100 °CWater boils at standard pressure.
−40 °F(−40 − 32) × 5 ÷ 9−40 °CThe one point where both scales read the same.
98.6 °F(98.6 − 32) × 5 ÷ 9 = 66.6 × 5 ÷ 937 °C exactlyA pure unit conversion; this tool does not interpret body temperature.
72 °F(72 − 32) × 5 ÷ 9 = 200 ÷ 922.2 °C (22.2222… repeating)Exact value repeats forever.
350 °F(350 − 32) × 5 ÷ 9 = 1590 ÷ 9176.7 °C (176.6666… repeating)Rounded half up to 1 decimal.
400 °F(400 − 32) × 5 ÷ 9 = 1840 ÷ 9204.4 °C (204.4444… repeating)Rounded half up to 1 decimal.
20 °C (reverse)20 × 9 ÷ 5 + 3268 °FCelsius to Fahrenheit direction.
37 °C (reverse)37 × 9 ÷ 5 + 3298.6 °F exactlyReverse of the 98.6 °F example.

Below absolute zero: readings colder than −459.67 °F / −273.15 °C are physically impossible, so the calculator returns a validation message instead of a number. Empty or non-numeric input does the same.

Fahrenheit to Celsius chart (reference table)

This fahrenheit to celsius chart is generated by the same engine as the calculator, so the numbers always match your chosen decimal places. Common fixed points and everyday readings are included.

Common temperatures converted from Fahrenheit to Celsius
Degrees Fahrenheit (°F)Degrees Celsius (°C)What it is

Oven temperature conversion table

These are the dial settings people most often need translated. The oven temperature conversion table below is a unit conversion only — it is not a cooking recommendation, a food-safety threshold or a recipe.

Oven dial temperatures in Fahrenheit and their Celsius equivalents
Oven setting (°F)Equivalent (°C)

Infographic: the fahrenheit to celsius formula step by step

Convert F to C: subtract 32, multiply by 5, divide by 9 (example: 72 °F)
Five boxes in a row: degrees Fahrenheit, minus 32, times 5, divided by 9, degrees Celsius, with the 72 degree example underneath. °F− 32× 5÷ 9°C 724020022.222…22.2 inputrounded
Step 1 — subtract 3240
Step 2 — multiply by 5200
Step 3 — divide by 922.2 °C

Bar lengths compare the intermediate numbers of this one example (40, 200, 22.222…). They illustrate the arithmetic, not a measurement scale.

Infographic: Fahrenheit and Celsius scales side by side

The two scales aligned at the fixed points of water
Two aligned scales showing boiling, the 98.6 to 37 reference point, freezing and minus 40. 212 °F98.6 °F32 °F−40 °F 100 °C37 °C0 °C−40 °C boilreference pointfreezesame reading on both scales

Fahrenheit scale (°F)

  • Water freezes at 32 °F and boils at 212 °F.
  • Used as the U.S. customary air and oven scale.
  • Reading rule: °C = (°F − 32) × 5 ÷ 9.

Celsius scale (°C)

  • Water freezes at 0 °C and boils at 100 °C.
  • Used almost everywhere else and in metric recipes.
  • Reading rule: °F = °C × 9 ÷ 5 + 32.

Aligned marks sit at the same physical temperatures, so equal heights on the two scales mean equal heat, not equal numbers.

Comparison: ways to convert 72 °F to Celsius

Same input, three approaches — what each one actually gives you
ApproachAnswer for 72 °FPrecisionBest used for
This calculator (exact integer math)22.2 °C at 1 decimal, exact 200/9 °CRounds only at display, up to 4 decimalsDocuments, homework, recipes, shipping forms
Formula by hand: (72 − 32) × 5 ÷ 922.2 °C if you keep every digitDepends on how early you roundQuick checks away from a keyboard
Rough halving shortcut: (72 − 32) ÷ 220 °C — about 2.2 degrees coldApproximate onlyA fast ballpark, never for final numbers

Comparison: a temperature reading vs a temperature change

Readings need the 32-degree offset; differences do not
SituationCorrect ruleExampleWhy
Converting a reading (thermostat, oven, forecast)°C = (°F − 32) × 5 ÷ 968 °F → 20 °CThe scales start at different points
Converting a change or difference (a drop, a lab delta)°C change = °F change × 5 ÷ 9an 18 °F drop → a 10 °C dropThe +32 offset cancels in a difference
Mixing the two upWrong resultTreating an 18 °F drop as 10 °C of readingReadings and differences are not interchangeable

The calculator on this page converts readings. If you need a difference, apply the × 5 ÷ 9 factor only — this tool does not yet have a separate difference mode.

Common mistakes and key conditions

  • Forgetting the 32. Dividing the raw Fahrenheit number by 1.8 is wrong; subtract 32 first (212 ÷ 1.8 = 117.8, not 100).
  • Multiplying instead of dividing. Going to Celsius means × 5 ÷ 9 (net smaller numbers). Going the other way means × 9 ÷ 5 + 32.
  • Rounding too early. Rounding the intermediate 40 × 5 = 200 result or a half-finished decimal changes the final answer. This tool rounds only at display.
  • Reading a difference as a reading. A change of N degrees uses only × 5 ÷ 9; a temperature level uses the full formula.
  • Expecting one decimal to be exact. Values like 72 °F (22.2222… °C) and 350 °F (176.6666… °C) repeat forever; the page tells you when a displayed number was rounded from a repeating value.
  • Below absolute zero. Anything colder than −459.67 °F / −273.15 °C is rejected with a message instead of converted.
  • Asking this page for advice. Unit conversion only: no fever interpretation, no weather forecast, no heat index or wind chill, no cooking-safety threshold, no instrument calibration.

Glossary

Fahrenheit (°F)
U.S. customary temperature scale where water freezes at 32 and boils at 212.
Celsius (°C)
Metric temperature scale where water freezes at 0 and boils at 100.
Kelvin (K)
Metric absolute scale starting at absolute zero; K = °C + 273.15. Optional output in this tool.
Fixed point
A defined reference temperature such as the freezing or boiling point of water at standard atmospheric pressure.
Repeating decimal
A value such as 22.2222… that never terminates; the calculator shows it at your chosen precision and labels it.
Absolute zero
The coldest physically possible temperature: −459.67 °F, −273.15 °C, 0 K.
Unit conversion
Changing the unit of the same quantity. It is not a measurement, a forecast or advice.

Frequently asked questions

How do you convert Fahrenheit to Celsius?

Subtract 32 from the Fahrenheit value, multiply the result by 5, then divide by 9: °C = (°F − 32) × 5 ÷ 9. Example: 72 °F becomes (72 − 32) × 5 ÷ 9 = 22.2 °C.

What is 98.6 °F in Celsius?

98.6 °F converts to exactly 37 °C, because (98.6 − 32) × 5 ÷ 9 = 66.6 × 5 ÷ 9 = 37. This page only shows the unit conversion and does not interpret body temperature.

What is 350 °F in Celsius?

350 °F is 176.7 °C when rounded to one decimal place; the exact value repeats as 176.6666… °C. Oven temperature conversion like this is a unit conversion, not a cooking recommendation.

What is the difference between a temperature reading and a temperature change?

A temperature reading uses the full formula with the 32-degree offset. A temperature change (a difference of N degrees) uses only the 5/9 factor, because the offset cancels out. A change of 18 °F is a change of 10 °C.

Can this calculator tell me if a temperature is a fever?

No. This tool only converts units. It gives no medical, fever, weather, cooking-safety or instrument interpretation. For guidance on body temperature, ask a clinician or check a public health source such as the CDC.

Answers state the arithmetic of this tool.

Official references, limitations and review record

Byline: Varnda Editorial Team.

  • NIST Office of Weights and Measures — https://www.nist.gov/pml/owm — reference starting point supplied with this brief.
  • NIST Special Publication 811, Guide for the Use of the International System of Units — https://www.nist.gov/pml/special-publication-811 — reference starting point.
  • NIST metric and unit-conversion resources — https://www.nist.gov/pml/owm/metric-si/unit-conversion — reference starting point.

The formulas are standard unit definitions and the arithmetic is tested inside the page, but the source check itself is NOT VERIFIED. Check the NIST pages above before citing this page formally.

What this tool does not do

It gives no medical or fever interpretation, no weather forecast, no heat-index or wind-chill calculation, no cooking-safety threshold, no instrument calibration and no legal or regulatory determination. It converts temperature units only.

Changelog

  • 2026-10-19 — Page created: both directions, Kelvin output, reference and oven charts, exact-arithmetic engine, formula version FC-2026-10-19. Source verification pending.

Corrections

Found a mistake? Use the contact or correction page published on this site (Varnda's own contact page, when present) and include the input value, the result you expected and a link to the source you used. If no such page is published yet, use the site's general contact route. No email address or form URL is claimed here because none was confirmed.

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Summary

This fahrenheit to celsius calculator gives you the converted value, the formula with your number substituted, an optional Kelvin reading, a full reference chart and an oven temperature conversion table — computed with exact decimal arithmetic and rounded only for display. Enter a value, choose the direction, and you have a trustworthy unit conversion in one second. It is a temperature converter for units, nothing more: for fever, weather or cooking decisions, use a qualified source.

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Fahrenheit to Celsius Converter - F to C Calculator
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