Temperature Converter

Convert between Celsius, Fahrenheit, Kelvin, and Rankine. Live reference points for common temperatures as you type.

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How to Use the Temperature Converter

Enter a temperature in any field — Celsius, Fahrenheit, Kelvin, or Rankine. All four values update simultaneously.

About This Tool

Celsius, Fahrenheit, Kelvin, and Rankine are the four temperature scales you will encounter in everyday life, science, and engineering. Celsius is used by most of the world for weather and cooking. Fahrenheit is standard in the United States for weather and oven temperatures. Kelvin is the SI unit used in science — it starts at absolute zero (−273.15 °C), the coldest physically possible temperature, making it essential for physics and chemistry. Rankine is an absolute scale built on the Fahrenheit degree, used by some US thermodynamics and aerospace engineers. Unlike length or weight conversions, temperature conversion is not a simple ratio — it involves both multiplication and an offset, which is why mental math often goes wrong. This tool converts all four scales simultaneously with a quick reference table for common benchmarks.

Quick Reference Table

Celsius	Fahrenheit	Kelvin	Rankine	Note
-40°C	-40°F	233.15 K	419.67 °R	Crossover point
0°C	32°F	273.15 K	491.67 °R	Water freezing
20°C	68°F	293.15 K	527.67 °R	Room temperature
37°C	98.6°F	310.15 K	558.27 °R	Body temperature
100°C	212°F	373.15 K	671.67 °R	Water boiling
180°C	356°F	453.15 K	815.67 °R	Baking low
200°C	392°F	473.15 K	851.67 °R	Baking medium
220°C	428°F	493.15 K	887.67 °R	Baking high

Frequently Asked Questions

How do I convert Celsius to Fahrenheit?

Multiply the Celsius value by 9/5, then add 32. For example, 25°C = (25 × 9/5) + 32 = 77°F. This converter handles both directions instantly.

How accurate are the Temperature Converter’s results?

Conversions use the exact mathematical relationships between scales — °F = °C × 9/5 + 32 for Celsius↔Fahrenheit, K = °C + 273.15 for Celsius↔Kelvin, and so on. Floating-point precision is the only source of error, and it appears only at the 12th significant digit or beyond. For practical use (cooking, weather, science homework, HVAC) the results are exact.

Is the Temperature Converter optimized for phones and tablets?

Yes. The interface uses touch-friendly 48×48 pixel hit targets, numeric-keyboard input types so iOS and Android show the right keypad, and a responsive layout that stacks the Celsius, Fahrenheit, Kelvin, and Rankine fields vertically on narrow screens. Pinch-zoom is not needed because the text meets WCAG minimum sizes.

Do I need to create an account to convert between Celsius, Fahrenheit, and Kelvin?

No. The Temperature Converter is completely free and anonymous — no account, no email, no signup. Enter a value in any scale (Celsius, Fahrenheit, Kelvin, or Rankine) and all conversions update instantly in your browser. There are no daily limits and no feature gating behind a paywall.

Why do Celsius and Fahrenheit meet at -40°?

The formulas °F = (°C × 9/5) + 32 and °C = (°F − 32) × 5/9 produce a crossover point where both scales read the same value. Solving °C = (°C × 9/5) + 32 gives °C = −40. This is the only temperature where Celsius and Fahrenheit are equal.

What is the difference between Kelvin and Celsius?

Kelvin and Celsius use the same degree size — a one-degree change in Celsius equals a one-degree change in Kelvin. The only difference is the zero point: 0 K is absolute zero (−273.15 °C), while 0 °C is the freezing point of water. To convert, add or subtract 273.15.

Created by The Toobits Team · Engineering & Editorial

Toobits is built, tested, and maintained by a small independent engineering team. Every tool is written in TypeScript, runs entirely in the browser, and is reviewed against its source formulas before publication.

Editorial policy · Updated April 2026

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