Temperature Converter

Convert Celsius, Fahrenheit, Kelvin, Rankine and Réaumur.

Temperature Converter

Universal unit converter engine

Conversion Category

From Value

Converted Result

Conversion Formula1 nm = 0.001 µm

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What does Temperature Converter do?

Convert between all five temperature scales with the formula shown for each conversion. The tool validates against absolute zero, so a physically impossible temperature is flagged rather than silently converted.

How to Use Temperature Converter

1
Enter a temperatureNegative values are fine above absolute zero.
2
Choose the scaleThe one your value is in.
3
Read every other scaleAll update together with the formula shown.

Key Features

All five scales converted at once
The exact formula shown for each conversion
Validation against absolute zero
Reference points marked: freezing, body temperature, boiling
Oven temperature table including gas marks

Frequently Asked Questions

How do I convert Celsius to Fahrenheit?

Multiply by 9/5 and add 32. 20 °C is (20 × 1.8) + 32 = 68 °F. For a rough estimate, double and add 30.

Why do temperature conversions need an offset?

Because the scales have different zero points. Celsius sets zero at water’s freezing point, Fahrenheit at a brine mixture, and Kelvin at absolute zero. A ratio alone cannot bridge them.

At what temperature do Celsius and Fahrenheit meet?

−40. It is the only point where the two scales give the same number, because their different slopes and offsets cross exactly there.

What is absolute zero?

0 K, which is −273.15 °C or −459.67 °F — the point where molecular motion reaches its quantum minimum. Nothing can be colder, so the converter rejects values below it.

100% Data Privacy

Conversions run in your browser using fixed, published factors. Nothing you enter is transmitted, and the tool keeps working with the network disconnected.