Free Temperature Converter — Celsius, Fahrenheit & Kelvin
Convert temperatures between all three scales instantly. Shows all three values simultaneously. Includes common temperature references.
The Three Temperature Scales Explained
Three temperature scales are used worldwide:
| Scale | Zero point | Boiling point of water | Used in |
|---|---|---|---|
| Celsius (°C) | 0°C = freezing point of water | 100°C | Most of the world (science, everyday) |
| Fahrenheit (°F) | 32°F = freezing point of water | 212°F | USA, some Caribbean countries |
| Kelvin (K) | 0K = absolute zero (−273.15°C) | 373.15K | Science, physics, chemistry |
Absolute zero is the lowest theoretically possible temperature — the point at which all molecular motion stops. It equals 0 Kelvin = −273.15°C = −459.67°F.
Correct usage is "300 K" not "300°K." Kelvin is an absolute scale — it doesn't use "degrees" because it doesn't reference a relative zero point like Celsius or Fahrenheit do.
Temperature Conversion Formulas
| From → To | Formula | Example |
|---|---|---|
| Celsius → Fahrenheit | °F = (°C × 9/5) + 32 | 100°C → (100 × 9/5) + 32 = 212°F |
| Fahrenheit → Celsius | °C = (°F − 32) × 5/9 | 98.6°F → (98.6 − 32) × 5/9 = 37°C |
| Celsius → Kelvin | K = °C + 273.15 | 0°C → 273.15K |
| Kelvin → Celsius | °C = K − 273.15 | 373.15K → 100°C |
| Fahrenheit → Kelvin | K = (°F − 32) × 5/9 + 273.15 | 32°F → 273.15K |
| Kelvin → Fahrenheit | °F = (K − 273.15) × 9/5 + 32 | 300K → 80.33°F |
For a rough estimate: double the Celsius temperature and add 30 to get Fahrenheit. Example: 20°C → (20 × 2) + 30 = 70°F (actual: 68°F). Reverse: subtract 30 from Fahrenheit and halve it. Good enough for weather checking.
Common Temperature Reference Chart
| Description | Celsius | Fahrenheit | Kelvin |
|---|---|---|---|
| Absolute zero | −273.15°C | −459.67°F | 0 K |
| Water freezes | 0°C | 32°F | 273.15 K |
| Cold winter day | −10°C | 14°F | 263 K |
| Room temperature | 20–22°C | 68–72°F | 293–295 K |
| Normal body temperature | 37°C | 98.6°F | 310 K |
| Fever threshold | 38°C | 100.4°F | 311 K |
| Hot summer day (India) | 40–45°C | 104–113°F | 313–318 K |
| Oven (baking) | 180°C | 356°F | 453 K |
| Water boils | 100°C | 212°F | 373 K |
| Sun's surface | 5,500°C | 9,932°F | 5,773 K |
How to Use the Tool (Step by Step)
- 1
Open the Temperature Converter
Go to ToolsArena Temperature Converter — no login needed.
- 2
Enter the temperature value
Type any temperature number, including negative values (e.g., −10 for below zero).
- 3
Select the source scale
Choose Celsius, Fahrenheit, or Kelvin as the input unit.
- 4
Read all conversions instantly
All three scale values appear simultaneously — Celsius, Fahrenheit, and Kelvin.
- 5
Copy the result
Click copy next to the value you need, or note all three for reference.
Frequently Asked Questions
What is 37 degrees Celsius in Fahrenheit?+−
37°C = (37 × 9/5) + 32 = 66.6 + 32 = 98.6°F. This is normal human body temperature. A fever is typically above 38°C (100.4°F).
How do I convert Celsius to Fahrenheit?+−
Formula: °F = (°C × 9/5) + 32. Example: 25°C → (25 × 9/5) + 32 = 45 + 32 = 77°F. For quick mental math: double the Celsius number and add 30 (gives approximate result).
What is 100 Fahrenheit in Celsius?+−
°C = (100 − 32) × 5/9 = 68 × 5/9 = 37.78°C. This is just above normal body temperature, which is why 100°F (37.8°C) is often considered the threshold for a mild fever.
Why does the US use Fahrenheit while the rest of the world uses Celsius?+−
The US retained the Fahrenheit scale (proposed by Daniel Gabriel Fahrenheit in 1724) largely due to historical inertia. The UK converted to Celsius in the 1970s. Fahrenheit's scale was designed so that 0°F was the coldest temperature Fahrenheit could reliably reproduce (a brine solution) and 96°F was human body temperature. Celsius (Anders Celsius, 1742) was designed around water's properties, making it more scientifically intuitive.
What is the difference between Celsius and Kelvin?+−
Celsius and Kelvin use the same scale size (a 1°C change equals a 1K change), but different zero points. Celsius zero (0°C) is the freezing point of water. Kelvin zero (0K = −273.15°C) is absolute zero — the coldest possible temperature. To convert: K = °C + 273.15.
Free Temperature Converter — Celsius, Fahrenheit & Kelvin
Convert temperatures between all three scales instantly. Shows all three values simultaneously. Includes common temperature references.
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