Temperature Converters
6 tools in this collection — free, instant, and private in your browser.
Temperature is one of the most universally encountered measurements in daily life, yet it uses three fundamentally different scales depending on context and location. Celsius (C) is the standard scale in virtually every country for weather, cooking, and medicine. Fahrenheit (F) remains the primary scale in the United States for everyday temperature references. Kelvin (K) is the absolute thermodynamic scale used in physics and chemistry, where zero represents the complete absence of thermal energy.
The conversion formulas are straightforward but easy to mix up under pressure. To convert Celsius to Fahrenheit, multiply by 9/5 and add 32. To go the other way, subtract 32 and multiply by 5/9. Kelvin is simply Celsius plus 273.15 — there are no degrees in Kelvin, only kelvins, and the scale never goes below zero. These converters handle all combinations instantly so you never need to recall the formula mid-task.
Knowing when to use which converter matters. Travelers moving between the US and elsewhere need Fahrenheit to Celsius daily for weather forecasts and body temperature references. Cooks following international recipes may encounter both Celsius and Fahrenheit oven temperatures in the same cookbook. Scientists and students working with gas laws, thermodynamics, or chemistry almost always need Kelvin, where absolute temperature is required for equations such as the ideal gas law to work correctly.
- For travel and everyday weather: Fahrenheit to Celsius or Celsius to Fahrenheit.
- For baking and cooking: the same pair, since oven temperatures in recipes differ by region.
- For scientific work: any of the Kelvin converters to translate lab readings into the absolute scale.
- For full flexibility across all three scales at once: the Temperature Converter.
A quick sanity check: water freezes at 0 C / 32 F / 273.15 K and boils at 100 C / 212 F / 373.15 K. These reference points make it easy to verify that a conversion result is in the right range before relying on it.
All temperature converters
All converter tools →Compare these tools
| Tool | What it does |
|---|---|
| Celsius to Fahrenheit | Convert Celsius to Fahrenheit instantly. Free temperature converter, no signup. |
| Celsius to Kelvin | Convert Celsius to Kelvin instantly. Free temperature converter, no signup. |
| Fahrenheit to Celsius | Convert Fahrenheit to Celsius instantly. Free temperature converter, no signup. |
| Fahrenheit to Kelvin | Convert Fahrenheit to Kelvin instantly. Free temperature converter, no signup. |
| Kelvin to Celsius | Convert Kelvin to Celsius instantly. Free temperature converter, no signup. |
| Temperature Converter | Convert temperature between Celsius, Fahrenheit, Kelvin, and Rankine instantly. |
Frequently asked questions
- What is the formula to convert Celsius to Fahrenheit?
- Multiply the Celsius value by 9/5 (or 1.8) and then add 32. For example, 25 C equals (25 x 1.8) + 32 = 77 F. A quick approximation is to double the Celsius value and add 30, which is less accurate but useful for mental estimates.
- What is absolute zero in Celsius and Fahrenheit?
- Absolute zero, the lowest possible temperature, is 0 K, which equals -273.15 C or -459.67 F. At this temperature, all thermal motion of atoms theoretically stops. It has never been achieved in practice, though laboratory experiments have come within billionths of a degree.
- Why does science use Kelvin instead of Celsius?
- Many physics and chemistry formulas require an absolute temperature scale where zero truly means no thermal energy. Equations like the ideal gas law (PV = nRT) only work correctly when T is in Kelvin. Using Celsius would produce mathematically invalid results because Celsius zero is an arbitrary reference point, not the absence of heat.