Work out tape correction (temperature) instantly with clear inputs, formula shown and shareable results.
A steel tape standardised at 20 °C is longer when hot, so it reads short and the correction is positive. The magnitude is the coefficient of expansion, about 11.5 microstrain per degree for steel, times the temperature difference times the measured length: fifteen degrees over a hundred metres is 17 millimetres.
Temperature correction
Correction = alpha x (T measured - T standard) x measured length
Correction = alpha x (T measured - T standard) x measured length. A steel tape standardised at 20 °C is longer when hot, so it reads short and the correction is positive.
Usually not. A dark tape in direct sun can be fifteen degrees above air temperature, which is why precise taping uses a tape thermometer clipped to the tape itself.
This calculator takes 4 inputs: Measured length, Temperature during measurement, Standardisation temperature, Coefficient of thermal expansion. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.