Temperature converter
Convert Celsius, Fahrenheit and kelvin with explicit absolute-zero boundaries.
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How it works
Convert an absolute temperature between Celsius, Fahrenheit and Kelvin. Unlike simple length conversions, these temperature scales have different zero points, so the calculation includes an offset as well as a scale factor.
A few things to know
Absolute temperatures only; temperature intervals require different formulas without the offsets. Does not estimate thermal expansion, cooking time or measurement uncertainty. Floating-point arithmetic and 12-significant-digit display apply; below absolute zero is invalid.
When to use this tool
Celsius, Fahrenheit and Kelvin describe temperature using different zero points and, for Fahrenheit, a different interval size. This converter translates an absolute temperature among all three scales and shows a reference table for the same reading. Its formulas include the necessary offsets, and it rejects inputs below absolute zero. Use it for an actual temperature reading or setpoint; a rise or fall in temperature is a different quantity and should not be converted with the same offset formulas.
- Read a Fahrenheit temperature specification in Celsius without rounding the original first.
- Express a scientific temperature recorded in Kelvin on everyday scales.
- Check an equipment setpoint’s equivalent value before entering it into a differently labeled interface.
How to use temperature converter
Enter an actual temperature
Use Value for the reading itself, such as 20 Celsius. Do not use it for a statement such as a temperature rise of 20 degrees.
Select the original scale
Choose From unit as Celsius, Fahrenheit or Kelvin. Negative Celsius and Fahrenheit readings are accepted when they stay at or above absolute zero.
Read the converted scale
Choose To unit and calculate. The metric gives Converted temperature; the table includes all three scales and can be downloaded as CSV.
Room-temperature scale conversion
Inputs
Value 20; From unit Celsius (°C); To unit Fahrenheit (°F).
Result
Converted temperature is 68 Fahrenheit. The same temperature is 293.15 Kelvin in the table.
What it means
The Fahrenheit calculation is 20 × 9/5 + 32 = 68. Kelvin is 20 + 273.15. These describe one reading; they do not mean a 20-degree temperature increase becomes a 68-degree increase.
Common mistakes to avoid
Applying offsets to temperature differences
A 10°C increase is an 18°F increase, not 50°F. This tool handles absolute readings, so use an interval formula for changes.
Using a degree symbol for Kelvin
Kelvin uses K rather than °K. The choice in the converter is labeled accordingly.
Treating conversion as cooking guidance
The converter changes the scale of a setpoint. It does not adjust cooking duration, oven performance or food-safety requirements.
Frequently asked questions
Definitions, edge cases, and practical next steps for this tool. Search all tool FAQs ↗
What is the Celsius-to-Fahrenheit formula?
Multiply Celsius by 9/5 and add 32. For the reverse direction, subtract 32 from Fahrenheit and multiply by 5/9. The offset aligns the scales’ zero points, while the multiplier accounts for the different degree sizes.
How do Celsius and Kelvin relate?
For an absolute temperature, Kelvin equals Celsius plus 273.15. Their interval sizes are equal, so a one-degree Celsius change is a one-kelvin change. The offset is needed for a reading, but not for a difference between readings.
What values are below absolute zero?
The tool rejects readings below 0 K, −273.15°C or −459.67°F, according to the selected source scale. Values exactly at those boundaries are accepted. A negative Celsius or Fahrenheit number alone is not necessarily below absolute zero.
Can Celsius and Fahrenheit have the same number?
They coincide at −40. Entering −40 in either of those scales produces −40 in the other. This is a consequence of the scale formulas, not evidence that the two scales are interchangeable at other temperatures.
Can this convert a temperature rise or drop?
The tool is designed for absolute temperature. For a difference, do not add 32 or 273.15: multiply a Celsius interval by 9/5 to get Fahrenheit, and treat Celsius and Kelvin intervals as equal. Keep readings and differences clearly labeled.
Does 100°C always mean boiling water?
The conversion of 100°C is 212°F regardless of context. Whether water boils at that reading depends on conditions such as pressure. The tool does not calculate phase changes or environmental conditions; it only converts the stated temperature.
Why does the result have many decimal places?
Outputs use up to 12 significant digits with floating-point arithmetic. Some inputs convert to repeating decimal values. Choose rounding consistent with the measuring instrument or specification rather than treating every displayed digit as physically measured accuracy.
Can the converter adjust an oven or thermostat?
It can supply the equivalent number, but it does not communicate with equipment or evaluate its calibration. Confirm the device’s scale, available increments and operating instructions before entering a converted setpoint.
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Sources and method
Use the references below to check definitions and platform guidance. The model’s scope and limits are explained above. Read our editorial standards.