Study Objectives Are staff “guesstimates” of children’s weights sufficiently accurate to be used in a paediatric emergency department where the majority of children are routinely weighed. To compare these “guesstimates” with the advanced paediatric life support (APLS) and Luscombe’s formulae.

Methods All staff at all levels were recruited to estimate children’s weights by visual estimation alone. These were recorded and compared with actual weight, the APLS formula and Luscombe formula estimates.

Results The APLS formula underestimated by 21%, clinicians underestimated by 7%. Clinician estimates closely mirrored the actual weights graphically. Those with mid-level experience were most accurate, underestimating by only 3.7%. Luscombe’s formula (3(age) + 7), although linear, underestimated weights by 3.1%.

Conclusion When weights of children are routinely measured, staff may be much more accurate at “guesstimating” than the APLS formula. Luscombe’s formula was even more accurate.