The effects of shape, size, and capture resolution on digital area measurement were investigated to accurately and precisely estimate leaf surface area. A digital scanner was used to measure two simple shapes (circle and square) at three resolutions (118.159, 236.270 and 472.441 pixels/cm) and five sizes (3.14, 12.58, 28.29, 50.29, and 78.60 cm²). Additionally, the accuracy and precision of two digital scanner models were compared using two shapes (circle and square) of similar size at five resolutions (29.528, 39.370, 59.055, 118.159, 236.270, and 472.440 pixels/cm). A method is described to measure leaf area using an image histogram and photographic software tools (Photoshop®). This method was validated by comparison of the digitally captured images to a leaf area meter (LI-COR® 3100). Overall, simple changes in shape have a statistically significant effect on the accuracy of digital measurements of area for some sizes and resolutions.