 This guide provides a comprehensive overview of estimating daily and monthly actual, potential, reference crop, and pan evaporation. The guide is aimed at researchers, consulting hydrologists, and practicing engineers who are interested in these topics. It covers various aspects of evaporation estimation, including estimating actual evaporation from deep lakes and farm dams, estimating potential evaporation as input to rainfall runoff models, and reference crop evapotranspiration for small irrigation areas and large irrigation districts. The guide also includes techniques to estimate actual evaporation from open-surface water and landscapes and catchments, as well as automatic or hard-wired calculation of evaporation estimates in commercial weather stations. Additionally, the guide addresses issues related to climate change, uncertainty in evaporation estimates, and 24-hour versus daylight-hour estimation of meteorological variables. The guide is supported by a supplement that includes worked examples of many procedures discussed in the paper, a program listing of Fortran 90, of Morton's Revap evaporation models, and tables of monthly class A-Pen coefficients for 68 locations across Australia and other information. This article was authored by T. A. McMahon, M. C. Peel, L. Lo, and others. We are article.tv, links in the description below.