Here we describe the standardised protocol used by the Canadian Airborne Biodiversity Observatory (CABO) to measure leaf water content and specific leaf area, using the WinFOLIA\u2122 software (R\u00e9gent Instruments). These leaf area and water measurements are done on a subset of leaves from the same bulk leaf sample used to measure leaf spectral reflectance and transmittance. Briefly, after removing their petioles, fresh leaves are weighed, rehydrated for 6 h, scanned for total leaf area and weighed again; they are then oven-dried at 65 \u00baC for 72 h, and weighed one last time. This allows us to measure leaf dry matter content and its complement, leaf water content, as well as leaf relative water content. Leaf area measurements are used to estimate specific leaf area, a key functional trait central to the leaf economics spectrum. Specific leaf area allows us to estimate equivalent water thickness and to convert concentrations of foliar biochemical constitutents from a leaf mass to a leaf area basis.