°C
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Instantly convert temperatures between Celsius, Fahrenheit, and Kelvin. Free browser-based tool with real-time conversion and formula reference.
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This tool converts temperatures instantly between Celsius (°C), Fahrenheit (°F), and Kelvin (K). Results update as you type — no button press needed. Each result card also shows the conversion formula used.
To convert from Celsius to Fahrenheit: multiply by 9/5, then add 32. The formula is °F = (°C × 9/5) + 32. For example, 100°C = (100 × 1.8) + 32 = 212°F.
Subtract 32, then multiply by 5/9. The formula is °C = (°F − 32) × 5/9. For example, 98.6°F = (98.6 − 32) × 5/9 = 37°C (normal body temperature).
Absolute zero — the coldest possible temperature — is 0 K, −273.15°C, or −459.67°F. At this point, all molecular motion stops.
Simply add 273.15. The formula is K = °C + 273.15. Kelvin uses the same degree size as Celsius but starts at absolute zero. So 0°C = 273.15 K.
−40° is the only temperature where Celsius and Fahrenheit are equal: −40°C = −40°F. This is a handy fact for extreme cold weather references.
By convention, Kelvin is an absolute thermodynamic scale defined by SI units. The unit is simply called "kelvin" (K), not "degrees kelvin", because it represents a fundamental unit of thermodynamic temperature.
Whether you're cooking a recipe from a foreign cookbook, solving a chemistry problem, or checking an international weather forecast, our temperature converter makes it effortless to switch between the world's three major temperature scales: Celsius (°C), Fahrenheit (°F), and Kelvin (K).
Just select your input scale, type a value, and all three results appear instantly — no button click required. Each result card also shows you the exact formula used, so you can learn and verify the math yourself.
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Celsius (°C) is the most widely used temperature scale in the world. Based on the freezing point (0°C) and boiling point (100°C) of water at sea level, it's the standard in science and in everyday life for most countries. The Celsius scale was proposed by Swedish astronomer Anders Celsius in 1742.
Fahrenheit (°F) is primarily used in the United States and a few other nations. Its reference points are 32°F for freezing water and 212°F for boiling water. Developed by Daniel Gabriel Fahrenheit in 1724, it was once the dominant scale in English-speaking countries. Normal human body temperature is approximately 98.6°F (37°C).
Kelvin (K) is the SI unit of thermodynamic temperature and the scale used in physics and engineering. It starts at absolute zero — the theoretically lowest possible temperature — and uses the same degree increment as Celsius. 0 K = −273.15°C. Unlike Celsius and Fahrenheit, Kelvin values are never negative.
The math behind temperature conversion is straightforward once you know the formulas:
°F = (°C × 9/5) + 32 — Celsius to Fahrenheit°C = (°F − 32) × 5/9 — Fahrenheit to CelsiusK = °C + 273.15 — Celsius to Kelvin°C = K − 273.15 — Kelvin to Celsius°F = (K − 273.15) × 9/5 + 32 — Kelvin to FahrenheitK = (°F − 32) × 5/9 + 273.15 — Fahrenheit to KelvinHere are some everyday temperature benchmarks across all three scales:
Temperature conversion comes up more often than you might think. Scientists and engineers typically work in Kelvin or Celsius; American recipes and weather reports use Fahrenheit; international cooking sites use Celsius. If you travel, follow global news, study chemistry, or work on engineering projects, you'll regularly need to move between these scales.
Our tool handles all six possible conversion directions and displays results simultaneously, so you can compare all three at once. The built-in formula display helps students learn the conversion math, not just get the answer.
This converter runs entirely in your browser — no data is sent to a server, nothing is stored, and there's no signup required. It works offline once the page is loaded, is mobile-friendly, and updates in real time as you type. Whether you need a quick one-off conversion or use it daily in your workflow, it's always ready.