The formula
How to calculate feels-like temperature
The "feels like" temperature — meteorologists call it apparent temperature — combines the air temperature with humidity and wind into a single number that better matches what the body actually experiences than the thermometer reading alone.
Humidity pushes the feels-like figure up: on a hot day, high moisture in the air slows evaporation from skin, which is the body's main cooling mechanism, so it feels hotter than the air temperature alone suggests. Wind pushes it down, by stripping away the thin layer of warmed air next to the skin faster than it can be replaced.
The inputs, one by one:
- Air temperature (°C)
- Relative humidity (%)
- Wind speed (m/s)
No submit button: type and the answer moves. Your inputs end up in the link, so the page can be shared already filled in.
The calculation runs on exactly the numbers currently in the fields above, recomputed in full each time — there is no dependency on the order values are entered in, so adjusting one input to test a scenario and then changing it back leaves the result exactly where it started.
Why feels-like temperature matters
This kind of calculation comes up in coursework, in a laboratory or field setting, and in professional practice, and the arithmetic is identical in every case — only the numbers being fed into it, and what is riding on getting them right, actually change.
This also functions as a reference implementation of the formula itself: where the exact form of an equation is in question, the one used on this page, stated in the formula section above, is the standard version found in the relevant textbooks and reference material.
It is worth remembering that a formula is only ever as good as the assumptions built into it, and most of the standard equations used across science and statistics carry at least one simplifying assumption — a linear approximation, an idealised gas, a normally distributed error term — that holds well in most ordinary cases and breaks down at the extremes. The result here reflects the standard formula exactly; whether that formula's assumptions are appropriate for your particular situation is a separate judgement worth making deliberately rather than assuming automatically.
In practice, a formula like this one is most often reached for at the exact moment a manual calculation needs checking against a deadline — a lab report due, a problem set to submit — which is precisely the situation where a small arithmetic slip is easiest to miss and most costly to leave uncorrected. Running the same inputs through an independent calculator catches that class of error reliably.
Worked example
Take the figures the calculator starts with:
- Air temperature: 25 °C
- Relative humidity: 50 %
- Wind speed: 3 m/s
That gives:
- Feels like: 24.1 °C
The figures above are the calculator's own default values, shown purely so the working is visible rather than hidden — the same steps apply exactly to your own numbers, entered in the fields at the top of this page.
Reading the result
The two effects can partly cancel out — a hot, humid day with a stiff breeze can feel closer to the actual temperature than a still, humid day does — which is why apparent temperature is a more useful number for deciding what to wear or whether conditions are risky than temperature alone.
Where this goes wrong. This calculator uses the Australian Bureau of Meteorology's formula, one of several apparent-temperature models in use worldwide; the US National Weather Service's heat index and wind chill (also on this site) are built for the hot-humid and cold-windy ends of the range specifically, and can give a noticeably different number for the same inputs. None of them are exact — they are all statistical fits to how people report feeling, not a physical measurement.
A result that is wrong by an exact factor of ten, a hundred or a similar round number is almost always a units error rather than a mistake in the formula itself — checking each input against the unit stated beside it is the fastest way to track it down.
They are related but not identical. Heat index is a US-specific formula for hot, humid conditions and does not account for wind. Feels-like (apparent temperature) formulas, including the one used here, fold in wind as well, so they apply across a wider range of conditions.
Sweat cools the body by evaporating, which requires the surrounding air to be able to absorb moisture. Dry air absorbs it readily, so sweat evaporates fast and cools effectively; humid air is already close to saturated, so sweat sits on the skin instead of evaporating, and the cooling effect weakens.
The answer it gives you is feels like. With 25 °C air temperature, 50 % relative humidity and 3 m/s wind speed, that comes to 24.1 °C. Change any field and the figure moves with it.
Generally, no more than the least precise input justifies — a result reported to six decimal places from inputs measured to two significant figures is implying a precision the calculation does not actually have. The calculator shows full precision so you can round appropriately for your own use.
Yes — the equation shown in the formula section above is the standard form used in textbooks and reference material for this calculation, not a simplified or approximate version.
Yes, in the sense that it applies the correct standard formula and returns an accurate result for the inputs given — but check your own course or publication's requirements for how results should be rounded, presented and referenced, since those conventions vary and are not something a calculator can know on your behalf.