Why can't temperature be converted with a single multiplier?

Because the scales have different zero points. Celsius puts zero at the freezing point of water, while Fahrenheit's zero comes from elsewhere, so 0 °C corresponds to 32 °F. An offset scale must be shifted before it is scaled, which is also why "what is 1 °C in °F" has no single answer while "what is 20 °C in °F" does.

Is there a quick mental approximation?

Doubling the Celsius value and adding 30 is the usual trick: 20 °C gives about 70 °F against an actual 68 °F. It stays within a couple of degrees across normal weather temperatures, which is fine for a feel but not for a real figure.

UNIT CONVERSION · CALCULATED FROM DEFINITIONS

Celsius to Fahrenheit Converter

Convert °C and °F both ways, with the formula shown and a reference table.

From

Formula°F = (°C × 1 − -17.777778) ÷ 0.555555556

Every unit in this category

°F33.8Fahrenheit

K274.15Kelvin

Common values

°C	°F
`0.5 °C`	`32.9 °F`
`1 °C`	`33.8 °F`
`2 °C`	`35.6 °F`
`3 °C`	`37.4 °F`
`5 °C`	`41 °F`
`10 °C`	`50 °F`
`15 °C`	`59 °F`
`20 °C`	`68 °F`
`25 °C`	`77 °F`
`30 °C`	`86 °F`
`50 °C`	`122 °F`
`75 °C`	`167 °F`
`100 °C`	`212 °F`
`150 °C`	`302 °F`
`200 °C`	`392 °F`
`500 °C`	`932 °F`
`1000 °C`	`1,832 °F`

About this tool

Enter Celsius to get Fahrenheit; the fields are linked both ways. Temperature is unlike length or mass because the scales have different zero points: 0 °C is 32 °F, not 0 °F, so no single multiplier works. The formula is °F = °C × 9/5 + 32, and the reverse is °C = (°F − 32) × 5/9. Both are shown on screen so the result can be checked, and the table covers weather, body, and oven temperatures.

How it works

Enter a temperature in Celsius, or type directly into the Fahrenheit field.
Check the formula shown alongside the result.
Use the table for weather, body, and oven temperatures.

Precision and definitions

Temperature scales have an offset, so a single multiplier cannot convert them; the full formula is always shown.

Privacy

Every conversion runs inside this browser. The values you enter are never uploaded, stored, or written to the URL or any log.

Frequently asked questions

Why can't temperature be converted with a single multiplier?: Because the scales have different zero points. Celsius puts zero at the freezing point of water, while Fahrenheit's zero comes from elsewhere, so 0 °C corresponds to 32 °F. An offset scale must be shifted before it is scaled, which is also why "what is 1 °C in °F" has no single answer while "what is 20 °C in °F" does.
Is there a quick mental approximation?: Doubling the Celsius value and adding 30 is the usual trick: 20 °C gives about 70 °F against an actual 68 °F. It stays within a couple of degrees across normal weather temperatures, which is fine for a feel but not for a real figure.

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