Temperature Converter | °C, °F, K
Convert between Celsius, Fahrenheit, Kelvin, and Rankine temperature scales.
°C (Celsius)
100
°F (Fahrenheit)
212
K (Kelvin)
373.15
°R (Rankine)
671.67
Conversion Working
°C → °F: 100 × 9/5 + 32 = 212
°C → K: 100 + 273.15 = 373.15
°C → °R: (100 + 273.15) × 9/5 = 671.67
Reference Points
| Reference | °C | °F | K | °R |
|---|---|---|---|---|
| Absolute Zero | -273.15 | -459.67 | 0 | 0 |
| Dry Ice (CO₂) | -78.5 | -109.3 | 194.65 | 350.37 |
| Water Freezes | 0 | 32 | 273.15 | 491.67 |
| Room Temp (25°C) | 25 | 77 | 298.15 | 536.67 |
| Body Temp | 37 | 98.6 | 310.15 | 558.27 |
| Water Boils | 100 | 212 | 373.15 | 671.67 |
| Oven (200°C) | 200 | 392 | 473.15 | 851.67 |
| Iron Melts | 1538 | 2800.4 | 1811.15 | 3260.07 |
Click any row to load that temperature.
What Is the Temperature Converter | °C, °F, K?
The Temperature Converter instantly converts between the four standard temperature scales: Celsius (°C), Fahrenheit (°F), Kelvin (K), and Rankine (°R). Enter any value in any unit and all four results update live. Copy any result to clipboard with one click. A built-in reference table of 8 key temperatures (absolute zero to iron's melting point) lets you instantly load any reference point.
- ›Celsius (°C): SI-derived unit; 0° = water freezes, 100° = water boils at 1 atm
- ›Fahrenheit (°F): used in the US; 32° = freeze, 212° = boil, 98.6° = body temp
- ›Kelvin (K): absolute scale; 0 K = absolute zero (−273.15°C), no negative values
- ›Rankine (°R): absolute scale based on Fahrenheit; used in US thermodynamics
- ›Click any reference point row to load that temperature instantly
Formula
Temperature Conversion Formulas
°C → °F
°F = °C × 9/5 + 32
°F → °C
°C = (°F − 32) × 5/9
°C → K
K = °C + 273.15
K → °C
°C = K − 273.15
°C → °R
°R = (°C + 273.15) × 9/5
°F → °R
°R = °F + 459.67
How to Use
- 1Enter a temperature value in the input field
- 2Select the source unit: °C, °F, K, or °R using the unit buttons
- 3All four converted values update instantly
- 4Click Copy next to any result to copy it to your clipboard
- 5Scroll down to the Reference Points table and click any row to load that temperature
- 6Your last input is saved automatically and restored on next visit
Example Calculation
Convert 100°C to all units:
K = 100 + 273.15 = 373.15 K
°R = (100 + 273.15) × 9/5 = 373.15 × 1.8 = 671.67°R
Convert 98.6°F (body temperature) to Celsius:
= 66.6 × 5/9
= 333 / 9
= 37.00°C ✓
Why Does Absolute Zero Exist?
Absolute zero (0 K = −273.15°C) is the theoretical temperature at which particles have minimum possible thermal kinetic energy. It cannot be reached in practice, the Third Law of Thermodynamics says you cannot reach 0 K in a finite number of steps. The coldest achieved temperature in a lab is ~10⁻¹⁰ K (100 picokelvins), reached by cooling clouds of atoms with lasers. The cosmic microwave background radiates at 2.725 K.
Understanding Temperature Converter | °C, °F, K
Temperature Scale Comparison
| Reference Point | °C | °F | K | °R |
|---|---|---|---|---|
| Absolute Zero | −273.15 | −459.67 | 0 | 0 |
| Nitrogen boils | −195.79 | −320.42 | 77.36 | 139.25 |
| Dry ice (CO₂) | −78.5 | −109.3 | 194.65 | 350.37 |
| Water freezes (0°C) | 0 | 32 | 273.15 | 491.67 |
| Room temp (25°C) | 25 | 77 | 298.15 | 536.67 |
| Human body | 37 | 98.6 | 310.15 | 558.27 |
| Water boils (100°C) | 100 | 212 | 373.15 | 671.67 |
| Iron melts | 1538 | 2800.4 | 1811.15 | 3260.07 |
Frequently Asked Questions
What is the formula to convert Celsius to Fahrenheit?
- ›°F = °C × 1.8 + 32
- ›Key reference: 0°C = 32°F, 20°C = 68°F, 37°C = 98.6°F, 100°C = 212°F
- ›The two scales cross at −40° (−40°C = −40°F)
- ›Quick estimate: °F ≈ 2×°C + 30 (within ~2°F for typical weather temperatures)
What is the difference between Kelvin and Celsius?
- ›K = °C + 273.15 (exactly, by SI definition)
- ›0 K = −273.15°C = absolute zero
- ›273.15 K = 0°C = water freezes
- ›373.15 K = 100°C = water boils
- ›Kelvin has no degree symbol: write 300 K, not 300°K
What is Rankine and when is it used?
- ›°R = °F + 459.67 (same relationship as K = °C + 273.15)
- ›°R = K × 9/5 (direct conversion between absolute scales)
- ›Used in US aerospace and thermodynamics textbooks
- ›Rarely used outside the US; Kelvin is the international standard
What is the boiling point of water in each scale?
- ›Sea level (1 atm): 100°C / 212°F / 373.15 K
- ›Denver (~1600m): ~95°C / 203°F
- ›Mount Everest (~8849m): ~70°C / 158°F
- ›Pressure cooker (2 atm): ~121°C / 250°F, why food cooks faster
What is normal human body temperature?
- ›Normal range: 36.1–37.2°C (97.0–99.0°F)
- ›Fever: above 38°C (100.4°F)
- ›Hypothermia: below 35°C (95°F)
- ›Diurnal variation: lowest ~4am, highest ~6pm (about 0.5°C range)
Why does the US use Fahrenheit instead of Celsius?
- ›Fahrenheit 0° was set to the coldest brine temperature Fahrenheit could achieve
- ›Celsius (Anders Celsius, 1742) set 0° at water's freezing point, more intuitive
- ›UK switched to Celsius in the 1960s–70s for official use
- ›Most US scientists and doctors use Celsius; Fahrenheit persists in everyday US weather
Is this temperature converter free?
Yes, completely free with no registration required. All calculations run locally in your browser.
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