How to Convert Temperature (F, C and Kelvin)
Published 2026-11-03
Temperature conversion is a high-volume search because weather, ovens and labs mix Fahrenheit and Celsius. Unlike length, these scales have an offset: 0°C is 32°F, not 0°F. Kelvin starts at absolute zero.
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Run these formulas with your own numbers. Math stays in your browser.
Open Temperature Converter →Our temperature converter takes one reading in Fahrenheit, Celsius, kelvin or Rankine and fills the other three. Anything below absolute zero is rejected. It converts a reading, not a medical diagnosis, and a 1°C change is 1.8°F — that shortcut is for differences, not for converting 68°F.
Open the temperature converter
The default 212°F is boiling water at 1 atm: 100°C, 373.15 K. Swap units with the chip if you started on the wrong scale.
The formulas
Go through kelvin internally so F, C and Rankine stay consistent. The classroom identities below match the result table.
C = (F − 32) × 5/9
F = C × 9/5 + 32
K = C + 273.15
Reference points
These are the same physical points on every scale. Boiling assumes standard pressure.
| Point | °C | °F | K |
|---|---|---|---|
| Absolute zero | −273.15 | −459.67 | 0 |
| Water freezes | 0 | 32 | 273.15 |
| Room (approx.) | 20 | 68 | 293.15 |
| Body (approx.) | 37 | 98.6 | 310.15 |
| Water boils (1 atm) | 100 | 212 | 373.15 |
Ovens, weather and differences
350°F is about 176.67°C. 25°C is 77°F. A freezer at −18°C is 0°F. If a recipe says “increase 10°C,” that is an 18°F change — do not run 10 through the absolute formula. Rankine is Fahrenheit from absolute zero; kelvin is written without a degree symbol.
- Enter the reading you have.
- Pick its scale, then the scale you want.
- Read the all-units table so you do not convert twice.
Worked conversions you can type in
68°F to Celsius: subtract 32, multiply by 5/9, get 20°C — room temperature on both scales. Reverse: 20 × 9/5 + 32 = 68. A 350°F oven is (350 − 32) × 5/9 ≈ 176.67°C; European dials are usually Celsius, so convert before you set the knob. Body-temperature 98.6°F is 37°C and 310.15 K; that is a unit change, not a diagnosis. Kelvin is Celsius plus 273.15 with no degree symbol. Rankine is Fahrenheit counted from absolute zero (F + 459.67). The temperature converter fills every scale from one reading and refuses anything below 0 K. A “rise of 10°C” is an 18°F difference — skip the 32 offset when the quantity is a change, not a reading. Weather apps in the US default to Fahrenheit; science class and most of the world use Celsius — convert once, then cook, travel or log the lab notebook in a single scale.
Use the free tool
Run these formulas with your own numbers. Math stays in your browser.
Open Temperature Converter →Frequently Asked Questions
What is absolute zero?
0 K, −273.15°C, −459.67°F, 0°R. Below that is refused.
Does 100°C always mean water boils?
Only at standard pressure. The conversion itself does not care about the substance.
Kelvin with a degree symbol?
No. Use K.
Can I convert a temperature difference?
Not with the offset formula. 1°C change = 1.8°F change.
Is 98.6°F medical advice?
No. It is a unit conversion of a common example reading.