These calculations are based on a model developed by The Gaia Movement, a webpage devoted to fighting climate change. They reference studies by https://uffnorge.org/ and the International Journal of Life Cycle Assessment to determine the positive environmental impact of donating your clothing (instead of sending it to the landfill) and putting that clothing to productive use (rather than producing more clothing). Learn more at: https://gaiaandglobalwarming.wordpress.com/about/re-using-clothes-saves-co2/