Temperature Converter

Convert between Celsius, Fahrenheit, Kelvin, and Rankine with formulas and instant results.

Value

From

Temperature Reference Points

Description	°C	°F	K
Water boiling point	100	212	373.15
Body temperature	37	98.6	310.15
Room temperature	20–22	68–72	293–295
Water freezing point	0	32	273.15
Absolute zero	−273.15	−459.67	0

Frequently Asked Questions

Use the formula: °F = (°C × 9/5) + 32. For example, 100°C = (100 × 1.8) + 32 = 212°F. The reverse is: °C = (°F − 32) × 5/9.

Absolute zero is the lowest theoretically possible temperature — 0 Kelvin = −273.15°C = −459.67°F. At absolute zero, particles have the minimum possible kinetic energy. It has been approached but never fully achieved in a laboratory.

Kelvin is the SI base unit of temperature. It starts at absolute zero and uses the same scale increment as Celsius. Convert: K = °C + 273.15. Kelvin is used in science, engineering, and astrophysics because it is an absolute (thermodynamic) scale with no negative values.

Rankine is an absolute temperature scale that uses Fahrenheit-sized degrees. °R = °F + 459.67. Absolute zero is 0°R. It is used in some engineering fields in the United States, particularly in thermodynamics calculations that require an absolute scale but use Fahrenheit units.

To convert Fahrenheit to Celsius, use °C = (°F − 32) × 5/9. For example, 98.6°F = (98.6 − 32) × 5/9 = 37°C. A quick mental trick: subtract 30 and halve the result for a rough estimate (e.g., 70°F → (70−30)/2 = 20°C; exact: 21.1°C).

Kelvin appears in everyday products more than most people realize. Light bulb color temperature is measured in Kelvin (2700K = warm white, 6500K = daylight). Camera white balance settings use Kelvin. Kelvin is also standard in scientific research, astrophysics, and cryogenics.

The classic normal body temperature is 98.6°F (37°C), but research shows the average is closer to 97.9°F (36.6°C) and varies by individual, time of day, and measurement method. A fever is generally considered to be 100.4°F (38°C) or higher.

The US adopted Fahrenheit in the 18th century before the metric system was established. Political resistance and the high cost of conversion have kept it in place. The Fahrenheit scale was designed so that human body temperature is near 100°F and salt water freezes at 0°F, but these benchmarks are not exact.

Common oven conversions: 325°F = 163°C (slow/low), 350°F = 177°C (moderate, most cakes), 375°F = 191°C, 400°F = 204°C (roasting), 425°F = 218°C, 450°F = 232°C (high heat, pizza). Gas marks are also used in UK recipes (Gas Mark 4 ≈ 350°F / 177°C).

Fahrenheit and Celsius are equal at −40° (both scales read −40 at this point). This is because the two scales converge when solving °C = °F in the conversion formula: (°F − 32) × 5/9 = °F gives °F = −40. This temperature occurs in extreme Arctic and Antarctic conditions.

About This Temperature Converter

This free temperature converter converts between Celsius, Fahrenheit, Kelvin, and Rankine. Enter a temperature in any scale and all others update instantly.

When to use this converter

Converting weather temperatures between °C and °F
Scientific and laboratory calculations in Kelvin
Understanding oven and cooking temperatures across countries

Standards & References

How It Works

Enter Temperature

Type any temperature value. Negative values are supported for sub-zero temperatures.

Select Scale

Choose the input scale and target scale. Unlike other converters, temperature uses formulas not simple multiplication.

See Result & Formula

The result and the conversion formula are displayed instantly so you can learn and verify the calculation.

Common Use Cases

Weather & Travel

Convert weather forecasts between Celsius and Fahrenheit when traveling internationally or following news from other countries.

Cooking & Baking

Convert oven temperatures between Celsius and Fahrenheit when following recipes from different countries or using imported kitchen equipment.

Medical & Body Temperature

Convert body temperature readings between Celsius and Fahrenheit when using medical devices calibrated in different scales.

Industrial & Engineering

Convert process temperatures for manufacturing, material science, and thermodynamic calculations across different measurement standards.

Science Education

Convert between Kelvin and Celsius for chemistry and physics coursework, especially for gas law calculations that require absolute temperature.

HVAC & Building

Convert thermostat settings and HVAC specifications between Celsius and Fahrenheit when working with equipment from different regions.

Related Converters

View all articles

Extreme Temperatures: From Blast Furnaces to Quantum Computers to Stellar Classification

Gas turbine blades operate above their own melting point, cooled by internal airflow. Quantum computers run at 15 millikelvin — colder than outer space. Here's industrial thermocouples and pyrometer accuracy, extreme industrial temperatures, cryogenic applications, and how stellar surface temperature determines star colour.

Jun 12, 2026

Fahrenheit vs Celsius: Why the US Kept One Scale and the Rest of the World Chose the Other

The US uses Fahrenheit by historical accident, not informed choice. Here's the origin of both scales, why Fahrenheit defenders have a point about weather ranges, absolute zero and superconductivity, food safety temperatures, and the one point where both scales agree.

Jun 9, 2026