Kalkulo

Temperature converter

Convert Fahrenheit, Celsius and Kelvin. °F = °C x 1.8 + 32; K = °C + 273.15. Water freezes at 32°F, boils at 212°F.

About this tool

Why use this tool

Americans use Fahrenheit for daily weather and cooking, while most of the world uses Celsius and science uses Kelvin. Converting matters for reading international recipes (Celsius ovens), understanding overseas weather forecasts, calibrating scientific equipment, and interpreting medical data (WHO fever guidelines in Celsius). The US is one of only three countries still using Fahrenheit; NIST maintains all official temperature references domestically.

How it works

°C = (°F − 32) × 5/9. °F = °C × 9/5 + 32. K = °C + 273.15. Absolute zero = 0 K = −273.15°C = −459.67°F. Water freezes at 32°F (0°C) and boils at 212°F (100°C) at sea level. Body temperature 98.6°F = 37°C. Fever threshold per CDC: 100.4°F (38°C).

Real example

A hot summer day in Phoenix at 110°F = 43.3°C. Oven at 350°F for baking = 177°C. A cold winter morning in Chicago at 10°F = −12°C. Boiling water: 212°F = 100°C = 373.15 K. Room temperature: 68–72°F = 20–22°C.

Practical tips

Quick mental math: to go from °C to °F, double and add 30 (25°C ≈ 80°F, accurate within 2° for common temperatures). Reverse: subtract 30 and halve. Kitchen shortcuts: 350°F (moderate oven) = 175°C, 400°F (hot) = 200°C, 425°F = 220°C. For fever, CDC/AAP defines 100.4°F rectal or ear as fever in infants. Weather apps (AccuWeather, Weather.com) let you toggle units. Thermostats: DOE recommends 78°F cooling and 68°F heating for efficiency. Scientific work always uses Kelvin — one Celsius degree change equals one Kelvin change.

Disclaimer

Conversions here are mathematically exact per NIST SI definitions. Household thermometers (medical, culinary, weather) have accuracy of ±0.5°F to ±3°F. For critical measurements (pharmaceutical, laboratory, food safety) use NIST-traceable calibrated instruments per FDA requirements.

Frequently asked questions

Why does the US still use Fahrenheit?⌄
It's a historical holdover. The Fahrenheit scale, defined in 1724, spread through the British Empire before Celsius existed. During the 20th century almost every country, including the UK, switched to Celsius for everyday use. The US kept Fahrenheit for weather, cooking and body temperature while adopting Celsius and Kelvin only for science and industry.
What is a normal body temperature in Fahrenheit?⌄
The traditional figure is 98.6 F (37 C), but a healthy range is roughly 97 to 99 F (36.1 to 37.2 C) and it varies through the day. A fever is generally defined as 100.4 F (38 C) or higher, measured orally.Source: CDC
How do I convert an oven temperature quickly?⌄
The exact formula is F = C x 1.8 + 32. Common US oven settings map to about 300 F = 150 C, 350 F = 177 C, 375 F = 190 C, 400 F = 205 C and 425 F = 218 C. A few degrees either way makes no practical difference to baking.
Can a Kelvin temperature be negative?⌄
No. 0 Kelvin is absolute zero, equal to -273.15 C, the lowest possible temperature. A Kelvin value is therefore always zero or positive, unlike Celsius and Fahrenheit where negative readings are common.
When would I ever use Kelvin?⌄
Kelvin is the SI base unit for temperature and is standard in physics, chemistry and engineering because it starts at absolute zero, so ratios and gas-law calculations work cleanly. Color temperature of light bulbs (for example 2700 K warm white, 5000 K daylight) is also given in Kelvin.Source: BIPM

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