Convert between Celsius, Fahrenheit, Kelvin, and Rankine instantly
From
To
Result
—
Enter a value to convert
Celsius
—
Fahrenheit
—
Kelvin
—
Rankine
—
Formula:—
Common Temperature Reference Points (click any row to load into converter)
Description
°C
°F
K
°R
Visual Scale Comparison
Conversion Formulas
Celsius → Fahrenheit
°F = (°C × 9/5) + 32
Fahrenheit → Celsius
°C = (°F − 32) × 5/9
Celsius → Kelvin
K = °C + 273.15
Kelvin → Celsius
°C = K − 273.15
Fahrenheit → Kelvin
K = (°F + 459.67) × 5/9
Kelvin → Rankine
°R = K × 9/5
Rankine → Kelvin
K = °R × 5/9
All Conversion Paths (x = input value)
From ↓ / To →
°C
°F
K
°R
Who Invented Each Scale?
°C
Anders Celsius (1742)
Swedish astronomer. Originally 100° = freezing, 0° = boiling. Flipped by Linnaeus after Celsius’s death. Adopted as the international standard in 1948 (SI).
°F
Daniel Fahrenheit (1724)
German physicist. Set 0° using a brine/ice/salt mixture, 96° as human body temperature. Produces non-round numbers for water milestones (32° & 212°).
K
Lord Kelvin (1848)
William Thomson anchored zero at absolute zero — the point where all molecular motion ceases. Used exclusively in physics, chemistry, and thermodynamics.
°R
William Rankine (1859)
Scottish engineer. Absolute scale using Fahrenheit-degree increments. Used in some US aerospace and legacy HVAC engineering contexts. Rarely seen outside North America.
Real-World Reference
🥶Freezing Point0°C = 32°F
🧍Body Temp37°C = 98.6°F
♨️Boiling Point100°C = 212°F
🌤️Warm Day25°C = 77°F
❄️Cold Day−10°C = 14°F
🔥Oven (Bake)175°C = 350°F
Quick Conversion Table
°C
°F
Context
-40
-40
Coldest inhabited places
-18
0
Deep freezer temp
0
32
Water freezes
20
68
Room temperature
37
98.6
Human body
100
212
Water boils
180
356
Baking temp
260
500
High-heat cooking
How to Use This Calculator
1
Select the Temperature Scale
Choose Celsius, Fahrenheit, Kelvin, or Rankine as your source scale.
2
Enter the Temperature
Type the numeric temperature value you want to convert.
3
View All Equivalents
The converter shows the temperature in all four scales simultaneously.
Formula & Methodology
Celsius to Fahrenheit
°F = (°C × 9/5) + 32
Multiply by 9/5 and add 32. Water freezes at 32 °F and boils at 212 °F.
Celsius to Kelvin
K = °C + 273.15
Add 273.15 to convert Celsius to the absolute thermodynamic scale.
Fahrenheit to Rankine
°R = °F + 459.67
Rankine is the absolute scale based on Fahrenheit degree increments.
A scale where water freezes at 0 and boils at 100 under standard atmospheric pressure.
Fahrenheit (°F)
A scale where water freezes at 32 and boils at 212; used daily in the United States.
Kelvin (K)
The SI unit of thermodynamic temperature; 0 K is absolute zero, the coldest possible temperature.
Rankine (°R)
An absolute temperature scale using Fahrenheit-sized degrees; 0 °R equals absolute zero.
Absolute Zero
The lowest theoretically possible temperature: 0 K, −273.15 °C, or −459.67 °F.
Real-World Examples
Example 1
Normal Body Temperature
98.6 °F
37.0 °C or 310.15 K — average healthy human body temperature
Example 2
Room Temperature
22 °C
71.6 °F or 295.15 K — comfortable indoor temperature
Key Temperature Reference Points
Event
°C
°F
K
Absolute zero
−273.15
−459.67
0
Water freezes
0
32
273.15
Room temperature
22
71.6
295.15
Body temperature
37
98.6
310.15
Water boils
100
212
373.15
Temperature Scales: History and Application
Origins of the Major Scales
Daniel Fahrenheit developed his scale in 1724 using a brine solution as the zero point. Anders Celsius proposed his centigrade scale in 1742, originally inverted (100 for freezing, 0 for boiling) before being flipped. Lord Kelvin introduced the absolute scale in 1848, anchoring zero at the point where all thermal motion ceases.
When to Use Which Scale
Celsius is the global standard for weather, cooking, and everyday science. Fahrenheit persists in the US for weather forecasts and cooking. Kelvin is mandatory in physical sciences, thermodynamics, and color temperature (photography). Rankine appears mainly in certain US engineering thermodynamics textbooks and legacy HVAC calculations.