Convert °C to °F

°C
-40°F

°F = °C × 9/5 + 32

Type a value in degrees Celsius and the answer in degrees Fahrenheit appears as you go. The conversion is a scale change rather than a simple factor, which is why the formula below has a shift in it, and it happens on your own machine — this page asks nothing of a server once it has loaded.

  • Where it runs

    In your browser. The number you type is never part of a request.

  • A scale, not a factor

    Celsius and Fahrenheit start at different zeros, so the conversion shifts as well as scales.

  • Answers as you type

    No button, no wait. The worked answer is already on the page before any script runs.

Celsius and Fahrenheit

Celsius puts zero at the freezing point of water and 100 at its boiling point, at sea level. Anders Celsius originally had the scale the other way up, with zero as boiling.

Fahrenheit puts freezing at 32 and boiling at 212, so a Fahrenheit degree is five ninths the size of a Celsius one. That difference in size is why the conversion needs a multiplication and not just a shift.

degrees Celsius to degrees Fahrenheit in practice

  • 200 °C is 392 °F

    — a hot oven.

  • -18 °C is -0.4 °F

    — a domestic freezer.

degrees Celsius to degrees Fahrenheit at a glance

°C°F
-40-40
-18-0.4
032
2068
3798.6
100212
200392

Every figure here is computed from the same definition the calculator uses, so the table cannot drift away from the answer above it.

Convert °C to °F: common questions

How many degrees Fahrenheit are in a celsius?

It depends where you start, which is what makes temperature different from every other unit here. Celsius and Fahrenheit do not share a zero, so there is no single number of one in the other — the conversion is °F = °C × 9/5 + 32.

Is this conversion exact, or rounded?

The relationship is exact — °F = °C × 9/5 + 32 is a definition, not a measurement. What is rounded is only the display, which stops at twelve significant figures.

Why does another converter show a slightly different number?

Almost always rounding rather than disagreement. Many converters cut the answer to two or four decimals, and some carry a factor that was rounded before the multiplication rather than after. The figures here are computed from the exact definitions and only rounded on the way to the screen.

Where these figures come from

The claims this page makes about temperature units are checkable, and these are the documents that settle them.

How this page works

The factor is a constant in the page and the arithmetic is four operations, so nothing is sent anywhere and nothing needs to be. The number you type never leaves the browser — there is no request for it to travel in.

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