Purpose To evaluate a new method for measuring corneal diameter in children. Design Prospective, cross-sectional study. Methods With a digital camera set at maximum focal distance, the authors photographed 92 children twice, each with a paper ruler taped to his or her forehead. Images were opened on a personal computer and the lower half of each eye was cut out and dragged to the ruler to record corneal diameter. The coefficient of variation was calculated for each eye, and nonlinear regression analysis used to correlate diameters with age. Results Directly after birth, corneal diameter was 9.98 mm, increasing to a plateau of 11.51 mm within the first 24 months of life. The coefficient of variation was 1.3%. Each measurement took no more than a few minutes. Conclusions This method allows very precise, fast, noncontact measurements of corneal diameter in newborn and young children.