Reaumur Calculator

Reaumur Calculator: convert reaumur instantly. Full formula, unit table, and worked example.

A temperature converter instantly switches between Celsius (°C), Fahrenheit (°F), and Kelvin (K) — the three most widely used temperature scales. Celsius and Fahrenheit are used for everyday measurements; Kelvin is the SI base unit used in scientific and engineering contexts. The US uses Fahrenheit for daily weather, cooking, and human body temperature; the rest of the world uses Celsius; all physical sciences use Kelvin.

Temperature conversions are needed for international cooking recipes, weather reports, science coursework, medical reference ranges, industrial process settings, and engineering specifications.

Enter a temperature value and select the source unit (°C, °F, or K).
The calculator instantly shows the equivalent in all three scales.
Use the formula reference to verify conversions manually or in formulas.

Temperature conversion formulas

°C to °F: °F = (°C × 9/5) + 32

°F to °C: °C = (°F − 32) × 5/9

°C to K: K = °C + 273.15

K to °C: °C = K − 273.15

Quick mental conversion: °F ≈ (°C × 2) + 30 (accurate within ~3°F for −10°C to 40°C range)

Key temperature reference points

Common temperature benchmarks

Absolute zero: 0 K = −273.15°C = −459.67°F (the coldest possible temperature). Water freezes: 0°C = 32°F = 273.15 K. Body temperature: 37°C = 98.6°F = 310.15 K. Water boils (at sea level): 100°C = 212°F = 373.15 K. Oven temperatures: 350°F (moderate) = 177°C; 400°F (hot) = 204°C; 425°F (very hot) = 218°C. The scales cross at −40°: −40°C = −40°F.

Conversion tips and best practices

For a quick Fahrenheit to Celsius estimate: subtract 32, then halve the result (within ~5% accuracy).
In the US, oven recipes specify Fahrenheit — convert to Celsius by subtracting 32 and multiplying by 5/9, or use the 350°F = 175°C, 400°F = 200°C rule of thumb.
Kelvin is always positive — there are no negative Kelvin values. If you get a negative answer in Kelvin, you have made an error.
Meteorological data from international sources uses Celsius — US weather apps using Fahrenheit can cause confusion when checking forecasts for international travel.

The hottest temperature ever recorded on Earth was 56.7°C (134°F) at Furnace Creek, Death Valley, California, on July 10, 1913.
The coldest temperature ever recorded on Earth was −89.2°C (−128.6°F) at Vostok Station, Antarctica, on July 21, 1983.
The surface temperature of the Sun is approximately 5,500°C (9,932°F / 5,773 K); the core temperature is approximately 15 million °C.

Common mistakes to avoid

Adding 273 instead of 273.15 for Celsius to Kelvin — use 273.15 for precision work.
Forgetting to subtract 32 before multiplying when converting Fahrenheit to Celsius — the offset must come first.
Applying the 9/5 factor as 1.8 in the wrong direction — multiplying when you should divide (or vice versa) gives temperatures wildly off.

Temperature conversion formulas are exact mathematical relationships. Industrial and medical temperature standards may define reference points at slightly different precisions — consult applicable standards (NIST, ISO, ITS-90) for metrological applications.