We compared direct and indirect methods for estimating egg volume in the Northern Fulmar Fulmarus glacialis and developed a simple photogrammetric technique. We found that more variability in measured egg volume was explained by a photogrammetric estimate of crosssectional area (78%), in comparison to an ellipsoidal formula derived from field measurements of egg length and breadth (61%), or a published formula (53%) that had been used in previous studies of this species. In future, this photogrammetric technique could also allow measurements of complex shape indices and reduce handling and disturbance at the nest.