Temperature Converter
Convert Celsius, Fahrenheit, kelvin, and Rankine with formulas that handle offsets correctly. The converter shows the selected result and a full table so weather, lab, engineering, and classroom temperatures stay aligned.
Base unit
kelvin
Supported units
4
Method
offset-aware
Live converter
Temperature conversion inputs
Enter a value, choose the source and target units, then inspect the full table for related physical units.
Converted result
20 °C
Input
68 °F
Output unit
°C
Base method
kelvin
Temperature in every supported unit
| Unit | Converted value | Unit name |
|---|---|---|
| °C | 20 | Degrees Celsius |
| °F | 68 | Degrees Fahrenheit |
| K | 293.15 | Kelvin |
| °R | 527.67 | Degrees Rankine |
Base unit
kelvin
Supported units
4
Method
offset-aware
Convert temperatures for weather, labs, and engineering
Weather and cooking
Move between Celsius and Fahrenheit for forecasts, ovens, recipes, and travel context.
Science classes
Convert Celsius to kelvin when thermodynamics or gas-law problems require an absolute temperature scale.
Engineering references
Compare Rankine and kelvin when a source uses absolute scales from different measurement traditions.
Temperature conversion formulas
Temperature conversions use offsets because the scales have different zero points. The converter normalizes through kelvin.
Working formulas
Celsius to kelvin
K = °C + 273.15
Kelvin is the absolute thermodynamic temperature scale used as the base.
Fahrenheit to kelvin
K = (°F + 459.67) x 5 / 9
The Fahrenheit offset must be applied before scaling.
Kelvin to Fahrenheit
°F = K x 9 / 5 - 459.67
The reverse conversion scales kelvin and then subtracts the Fahrenheit offset.
Symbols
- K - kelvin
- The absolute temperature value used as the base conversion scale.
- °F, °C, °R - temperature scales
- Fahrenheit, Celsius, and Rankine values converted through kelvin.
Temperature values, intervals, and trustworthy precision
This is a live value converter: each input produces a fresh result and four-scale comparison table. Use the separate temperature chart when you need a fixed set of common reference points rather than a calculation for one measurement.
Exact scale relationships
The Celsius-kelvin offset is exactly 273.15, and one Celsius degree has the same interval size as one kelvin. Fahrenheit and Rankine intervals are 5/9 of a kelvin, so the converter must apply both the interval ratio and the correct zero-point offset for temperature values.
Do not apply the +32 or 273.15 offsets to a temperature difference. A change of 18 degrees Fahrenheit is a change of 10 degrees Celsius, but an absolute value of 18 degrees Fahrenheit is not 10 degrees Celsius.
Worked conversion: 68 degrees Fahrenheit
(68 - 32) / 1.8 = 20 degrees Celsius; 20 + 273.15 = 293.15 K
The converter returns 20 degrees Celsius and 293.15 kelvin. Both are exact consequences of the scale definitions for this input, although a real thermometer reading may carry less measurement precision.
Round to the measurement, not the screen
The result formatter removes binary floating-point noise and shows at most 12 significant digits. That display precision does not make the source measurement more accurate; a whole-degree forecast normally should not become a many-decimal laboratory claim.
When copying a result, include the unit symbol and retain only the digits justified by the source. Values below 0 K can be calculated algebraically, but they are not physically meaningful thermodynamic temperatures.
Choose this page for an entered value and an immediate four-scale table. Choose the temperature chart for a printable sequence of common values and reference points.
Open the printable temperature conversion chartLimits to keep with the result
- The page converts scale values; it does not estimate thermometer calibration, uncertainty, or heat transfer.
- Use interval formulas without zero-point offsets when converting temperature changes rather than temperature readings.
- Treat results below absolute zero as invalid for physical applications even if the arithmetic is displayed.
Why temperature needs a dedicated converter
Handles offsets correctly
- Temperature conversion is not a simple unit-factor multiplication.
- The converter applies the correct zero-point offset before or after scaling.
- Kelvin and Rankine are absolute scales, while Celsius and Fahrenheit have offset zero points.
All scales visible
- The table shows Celsius, Fahrenheit, kelvin, and Rankine for the same input.
- Users can compare weather-style and science-style results without retyping the value.
- The formulas below the tool make classroom and lab checks easier to explain.
Built for temperature-sensitive work
Weather and travel
Convert forecasts and climate notes between Celsius and Fahrenheit quickly.
Science labs
Convert Celsius to kelvin for gas laws, thermal energy, and absolute-temperature calculations.
Engineering notes
Compare kelvin and Rankine when reading technical references that use absolute scales.
How it works in three quick steps.
Enter the temperature
Type the value from a weather report, recipe, lab note, instrument reading, or homework problem.
Choose source and target scales
Select Celsius, Fahrenheit, kelvin, or Rankine. The result updates immediately.
Check the offset formula
Review the formula notes because temperature conversion uses offsets, not only multiplication.
Reuse temperature results cleanly
Copy result
Copy the selected temperature conversion with scale labels for notes, reports, and worksheets.
Print the table
Print all four temperature scales when a lab or classroom needs repeated comparisons.
Show formulas
Use the visible formula notes to avoid treating temperature like a simple factor conversion.
Frequently Asked Questions
Why is temperature conversion different from other unit conversions?
What temperature units are supported?
Can kelvin be negative?
What is the formula for Celsius to Fahrenheit?
When should I use kelvin instead of Celsius?
Related physical unit converters
About this temperature converter
Temperature conversion deserves its own tool because it does not behave like length, mass, speed, or pressure conversion. Celsius and Fahrenheit have different zero points, while kelvin and Rankine are absolute scales. A correct converter must handle both offset and scale.
The page routes conversions through kelvin so absolute-temperature logic stays visible. That makes the tool useful for everyday Celsius-Fahrenheit checks and for science problems where kelvin is required.
The table shows every supported scale at once. That helps users compare a weather value, lab value, and engineering value without repeating the same input several times.
Who maintains this page
Ownership and review
Written and maintained by the Toolarithm editorial team. No review date is shown without a maintained editorial record. No independent professional review is claimed.
Methodology
Conversion factors are normalized to canonical units and checked in both directions. Exact definitions and offset formulas are preferred over rounded lookup values.
Read the editorial methodologyDates and sources
Review dates change only after a substantive method or content check.
Keep building