Aim: Split-thickness skin grafts (STSG) taken using calibrated powered dermatomes are assumed to yield a graft of uniform thickness, though this assumption has never been analysed statistically. This study aims to test that assumption in a paediatric population. Method: STSGs from a consecutive cohort of paediatric patients were analysed for mean thickness, measured from a central biopsy. All STSGs were taken from the thigh at a dialled thickness of 0.007 in. Data were analysed using non-parametric methods. Results: There were 140 STSGs taken from 91 children. The median thickness was 6.94 thousandths of an inch, with a spread of thicknesses about this median (IQR 5.05–9.28). There were no significant differences when results were analysed by surgeon, patient age or gender, swipe number within the case, or the number of previous passes with the same blade. Conclusion: STSG thickness is inconsistent, with a broad spread about a median value. This study provides no data to suggest there are pre-operative predictors of STSG thickness being significantly more or less than that dialled on a powered dermatome.