Forestation can be quite controversial so we err very heavily on the safe side. Our calculation is on the site[1] but I'll copy it here for clarity as well:

Forestation can be quite controversial so we err very heavily on the safe side. Our calculation is on the site[1] but I'll copy it here for clarity as well: * We use an average CO₂ sequestration rate of 10.875kg of CO₂/tree/year. * We only take the first 5 years of the trees' carbon sequestration into account. What gets sequestered after this is a gift to our planet and we don’t sell that. * To mitigate chances of loss due to disease or fires we double plant (meaning we buy double the number of trees that we need to). Therefore for every two trees we purchase we assign a removal value of 54.375kg (10.875kg * 5 years). For one tonne of carbon that is (1000kg / 54.375kg) * 2 trees = 37 trees (rounded). At $0.15 per tree that's $5.5. [1] https://docs.cdrplatform.com/docs/removal-method#forestation https://docs.cdrplatform.com/docs/removal-method#forestation