Carbon is stored by forests in different pools, including living trees, soil, and down dead wood. Forest carbon is also stored in products made from harvested trees. Available methodsfor estimating the size of this carbon pool can be difficult to use, especially when tracking multiple stands or harvests over time. PRESTO (PRoduct EStimation Tool Online) is a web-based tool to help land managers and owners estimate the amount of carbon stored in products over time based on harvest volume, geographic region, and wood type. PRESTO was designed to be used by everyone from industrial forestland owners to small landowners, and can be used in an “easy” mode to explore the effects of changing the amounts of longer- and shorter-lived products, or with specific harvest data to produce stand-level reports. A user guide is available at www.treesearch.fs.fed.us/pubs/47240. PRESTO is currently available as a stand-alone tool, but may become part of the i-Tree suite of tools in the future.