What this converter does
This converter takes a value in Celsius, Fahrenheit or Kelvin and shows it in all three, converting through Celsius as the intermediate.
It exists because temperature appears throughout forensic work — body cooling, entomological accumulation, storage requirements — and published sources use different scales. This is a teaching and planning aid, not a casework tool.
Convert temperature
Before you convert
- Select the unit your input is in. Getting that wrong produces a plausible but wrong figure.
- Kelvin has no degree symbol and no negative values. A negative Kelvin input is physically meaningless.
- The output shows three decimal places, which exceeds the precision of almost any practical measurement. Round appropriately.
- Body cooling and entomological work in the UK use Celsius throughout.
Celsius and Fahrenheit coincide at −40, which is a useful check on any conversion. Kelvin is offset from Celsius by exactly 273.15 with the same degree size, so a temperature difference is numerically identical in Celsius and Kelvin — which matters when a formula uses a difference rather than an absolute value.
How this calculator works
Convert to Celsius, then out again:
From Fahrenheit: C = (F − 32) × 5 ÷ 9
From Kelvin: C = K − 273.15
To Fahrenheit: F = (C × 9 ÷ 5) + 32
To Kelvin: K = C + 273.15Using Celsius as the intermediate means three conversions rather than six, and adding another scale would need one more rather than several. The same approach is used by the bone measurement converter.
Worked example: 20°C
Using the default figures — 20 with Celsius selected:
- 20.000 °C
- 68.000 °F
- 293.150 K
A useful sanity check: 20°C is comfortable room temperature and 68°F is the figure an American thermostat would show for the same room. If a conversion produces something that fails a common-sense check like that, the input unit is usually the reason.
Common mistakes
- Selecting the wrong input unit. The result is plausible and wrong.
- Converting a temperature difference as though it were an absolute value. Differences do not take the 32 offset.
- Entering a negative Kelvin value. It has no physical meaning.
- Reporting three decimal places. Round to the precision of the measurement.
- Assuming a source's units. Check rather than infer.
Frequently asked questions
Why does forensic work need Kelvin?
Rarely for measurement, but thermodynamic relationships are expressed in absolute temperature, so it appears in the derivation of cooling models even where the practical measurements are in Celsius. Its main practical use is as a reminder that a temperature difference is the same number in Celsius and Kelvin.
How precise are scene temperature measurements?
A calibrated probe reads to a tenth of a degree, but the meaningful uncertainty is larger — where the probe was placed, how long it equilibrated, and whether the position represents the conditions the body or larvae actually experienced. Recording the position matters as much as the reading.
Why do Celsius and Fahrenheit meet at −40?
Because the two scales have different zero points and different degree sizes, the lines describing them cross once. Solving F = (C × 9 ÷ 5) + 32 for F = C gives exactly −40. It is a convenient check that a conversion is implemented correctly.
What temperature should evidence be stored at?
It depends entirely on the material. Biological samples generally require refrigeration or freezing to defined temperatures, and the requirements come from the receiving laboratory rather than a general rule. Storage temperature is recorded as part of continuity for anything temperature-sensitive.
Is what I enter stored?
No. Everything you enter is processed in your browser and is never transmitted or retained. Even so, treat any public website as an unsecured environment and do not enter identifiable case information.
Related tools
References
- GOV.UK — Forensic Science Regulator codes of practice on measurement and calibration
- Met Office — UK temperature records, published in Celsius
Sources are checked at publication and can change — how I choose and check references.