TRENES

Temperature Converter

Convert temperatures between Celsius, Fahrenheit and Kelvin.

Written by Ahmet Tur · Reviewed by Kübra Yıldız · Updated

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Temperature is measured on three scales, and which one you meet depends on where you are: Celsius across most of the world, Fahrenheit in the US, and Kelvin in science. Converting between them isn't a simple multiply — each scale has a different zero point and step size — which is exactly why a converter helps.

Enter a value, pick the scales, and the result appears with all three temperatures shown at once.

Temperature Converter: step-by-step worked example

What is 100 °F in °C?

Example inputs
Value
100
From
Fahrenheit (°F)
To
Celsius (°C)
  1. 1

    How the scales relate

    100 °C span = 180 °F span → 9/5; kelvin has the same step as Celsius but starts at absolute zero (−273.15 °C)

    180 ÷ 100 = 1.8 = 1.8

  2. 2

    First convert to Celsius (common scale)

    °C = (°F − 32) × 5/9 · °C = K − 273.15

    (100 − 32) × 5 ÷ 9 = 37.78 °C

  3. 3

    Convert to the target scale

    °F = °C × 9/5 + 32 · K = °C + 273.15

    37.78 °C = 37.78 °C

  4. 4

    The same temperature on all three scales

    °C · °F · K

    = 37.78 °C = 100 °F = 310.93 K

Result · Converted value37.78 °C
Where it sits on the Celsius scale
37.78 °C
-20 °C0 °C20 °C35 °C37.5 °C42 °C100 °C110 °C
  • Below freezing
  • Cold–cool
  • Mild–warm
  • Body temp.
  • Fever
  • Below boiling
  • Above boiling
Reference points on the absolute (kelvin) scale
  • Absolute zero0 K
  • Water freezes (0 °C)273.15 K
  • Body (37 °C)310.15 K
  • This example310.93 K
  • Water boils (100 °C)373.15 K

Good to know: Kelvin takes no degree sign (300 K, not “300 °K”) and is never negative. When converting a temperature DIFFERENCE, skip the +32: a 10 °C rise is an 18 °F rise.

Temperature Converter — how it works

The formulas

ConversionFormula
°C → °F(°C × 9/5) + 32
°F → °C(°F − 32) × 5/9
°C → K°C + 273.15
K → °CK − 273.15

Fahrenheit and Celsius differ in both their zero point (32°F = 0°C) and their step size (a 1°C change is 1.8°F). Kelvin shares Celsius's step but starts at absolute zero (−273.15°C).

Reference points worth knowing

  • Water freezes: 0°C = 32°F = 273.15 K
  • Water boils: 100°C = 212°F = 373.15 K
  • Body temperature: 37°C = 98.6°F
  • Room temperature: ~20–22°C = 68–72°F
  • The two scales meet at −40°: −40°C = −40°F

Why Kelvin has no degree sign

Kelvin is an absolute scale starting at absolute zero — the coldest possible temperature, where molecular motion stops. It's written "300 K", not "300°K", because it measures from a true zero rather than an arbitrary reference. Scientists use it because it makes gas and thermodynamic laws simple.

Where it helps

  • Reading a US recipe or weather forecast in Fahrenheit
  • Converting a scientific figure into Kelvin
  • Setting an oven, checking a fever, or understanding a climate figure abroad

Worked example

A recipe says to bake at 25°C but your oven is in Fahrenheit. Converting: (25 × 9/5) + 32 = 45 + 32 = 77°F. The tool also shows 298.15 K for the same temperature. For a couple of familiar checks: a 37°C body temperature is (37 × 9/5) + 32 = 98.6°F — the classic "normal" reading — and water freezing at 0°C is exactly 32°F and 273.15 K. Notice the step-size difference: going from 0°C to 100°C spans only 100 degrees, but the same range is 32°F to 212°F, a span of 180 — which is why you can't just add or multiply by one number.

Temperature conversion table (°C, °F, K)

°C°FKelvin
-40-40233.2
-20-4253.2
-1014263.2
032273.2
1050283.2
2068293.2
2577298.2
3086303.2
36.697.9309.8
3798.6310.2
40104313.2
50122323.2
100212373.2

Frequently asked questions

How do I convert Celsius to Fahrenheit?+

Multiply by 9/5 and add 32: 25°C × 9/5 + 32 = 77°F. To go the other way, subtract 32 and multiply by 5/9. The tool does both and shows Kelvin too.

How do I convert Fahrenheit to Celsius?+

Subtract 32, then multiply by 5/9: (98.6 − 32) × 5/9 = 37°C. That's normal body temperature. Just pick the scales and enter the value.

What is Celsius in Kelvin?+

Add 273.15: 0°C = 273.15 K, 25°C = 298.15 K. Kelvin uses the same step size as Celsius but starts at absolute zero (−273.15°C).

Why is Kelvin written without a degree sign?+

Because it's an absolute scale measured from absolute zero, not from an arbitrary reference point. It's written "300 K", not "300°K" — the convention for absolute temperature scales.

At what temperature are Celsius and Fahrenheit equal?+

At −40°: −40°C equals −40°F exactly. It's the single point where the two scales cross, a handy fact for checking a conversion.

What is a normal oven temperature in each scale?+

A moderate oven of 180°C is 356°F (about 350°F in US recipes) and 453.15 K. The tool converts any baking temperature between the scales instantly.

About this page

Publisher:
Kalkoro — Teknolojig Bilişim Teknolojileri A.Ş., İstanbul
Written by:
Ahmet Tur — Editor (Math, date & time, unit conversion, physics & chemistry, everyday tools)
Reviewed by:
Kübra Yıldız — Editor

Parameters come from official sources; the last update date is shown at the bottom of the page.

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