In forensic intelligence-gathering it would be useful to be able to estimate the size of a perpetrator's foot from a standing bare footprint found at the scene of crime. Currently, the advice is to add a fixed amount to the length of the footprint (typically 1.5 or 2.0 cm), but there is little evidence for this approach. This study used measured footprint and actual foot lengths from 146 participants from the white British student population of a University in the UK. Data were analysed using multiple regression with foot length as the dependent (outcome) variable and footprint length and sex as the independent variable/factor respectively. Sex was not a significant predictor. The regression equation for the best estimate of the foot length is 19.89 + 0.95 × print length ± 8 mm.