Temperature Converter – Celsius, Fahrenheit, Kelvin & 5 More Scales
Convert between 8 temperature scales — Celsius, Fahrenheit, Kelvin, Rankine, Delisle, Newton, Réaumur, and Rømer. Includes an all-scales comparison table, a built-in reference points section (absolute zero, body temperature, boiling point), and context-aware facts for your temperature value.
0 °C in all scales
Reference Points
8 Scales
Celsius, Fahrenheit, Kelvin, Rankine, Delisle, Newton, Réaumur & Rømer.
Instant
Results update in real time as you type.
Fun Facts
Context-aware notes about your temperature value.
Included Temperature Converter Tools
Temperature Scale Converter
Convert between any two of 8 scales — Celsius, Fahrenheit, Kelvin, Rankine, Delisle, Newton, Réaumur, Rømer — with a swap button and instant result.
All-Scales Comparison Table
See your value expressed across all 8 temperature scales simultaneously for a full cross-scale comparison.
Reference Points Table
A built-in quick reference showing Absolute Zero, Water Freezing, Body Temperature, and Water Boiling in °C, °F, and Kelvin.
Context-Aware Fun Facts
Each conversion shows an auto-generated fact based on the temperature — from absolute zero to hotter than the surface of the Sun.
Who Uses a Temperature Converter
Cooking & Baking
Convert oven temperatures between Celsius and Fahrenheit when following international recipes — US recipes use °F, most others use °C.
Weather & Travel
Quickly convert weather forecasts when traveling between countries. 30°C summer heat = 86°F; a cold 0°C day = 32°F (freezing point).
Science & Engineering
Convert between Celsius and Kelvin for thermodynamics, chemistry, or physics calculations where absolute temperature is required.
How to Convert Temperature
Enter a temperature
Type your temperature value into the input field.
Choose scales
Select your source scale (From) and target scale (To) from the dropdowns.
Read the result
The converted temperature appears instantly with a context-aware fun fact below.
Check all scales
The All Conversions table shows your value in all 8 scales, and the Reference Points table provides common benchmarks.
Celsius to Fahrenheit Formula – and Why the Two Scales Diverge
The Celsius and Fahrenheit scales are both linear but start at different zero points and use different step sizes. Celsius is defined so that water freezes at 0°C and boils at 100°C at sea level — 100 evenly divided degrees between two natural reference points. Fahrenheit was originally calibrated using brine (0°F) and human body temperature (96°F, later adjusted to 98.6°F), which is why its numbers feel less intuitive for everyday weather and cooking. The conversion formula is: °F = (°C × 1.8) + 32 — multiply by 1.8 to stretch the scale, then add 32 to shift the zero point. Going the other way: °C = (°F − 32) / 1.8. A useful mental shortcut: double the Celsius value and add 30 gives a rough Fahrenheit estimate (20°C → 70°F is close to 68°F actual). The one temperature where both scales agree is −40°: −40°C = −40°F exactly — the result of the two conversion constants canceling out.
Kelvin, Rankine, and the Absolute Temperature Scales
Kelvin (K) and Rankine (°R) are called absolute temperature scales because they begin at absolute zero — the theoretical minimum temperature where all thermal motion ceases. Kelvin is the SI base unit and uses the same step size as Celsius: 1 K increase = 1°C increase, but 0 K = −273.15°C. This means converting Celsius to Kelvin is simply adding 273.15. Kelvin is essential in thermodynamics, chemistry (ideal gas law: PV = nRT uses T in Kelvin), and astrophysics — stellar surface temperatures are reported in Kelvin (the Sun's surface is roughly 5,778 K). Rankine does the same thing for Fahrenheit: it starts at absolute zero but uses Fahrenheit-sized steps. 0°R = −459.67°F = 0 K. Rankine is used in some US engineering contexts. The four historical scales — Delisle, Newton, Réaumur, and Rømer — are rarely used outside historical research but are included here for completeness and curiosity.
Frequently Asked Questions
- How do I convert Celsius to Fahrenheit?
- The formula is °F = (°C × 9/5) + 32. For example, 100°C = 212°F. Select Celsius in From, enter your value, and choose Fahrenheit in To for an instant result.
- What is Kelvin and why is it used?
- Kelvin is the SI base unit of temperature. Unlike Celsius or Fahrenheit, it has no negative values — it starts at absolute zero (0 K = −273.15°C). It is used in physics, astronomy, and scientific calculations.
- What are Delisle, Newton, Réaumur, and Rømer?
- These are historical temperature scales rarely used today. Delisle, Newton, Réaumur, and Rømer were each defined independently in the 18th century before Celsius and Fahrenheit became standard. ToolMint supports all 8 for completeness.
- What is absolute zero?
- Absolute zero is the lowest theoretically possible temperature: 0 K = −273.15°C = −459.67°F. At this point all classical molecular motion stops.
- What is normal human body temperature in Fahrenheit and Kelvin?
- Normal body temperature is approximately 37°C = 98.6°F = 310.15 K. This is one of the reference points shown in the built-in Reference Points table.
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