I’m a big fan of both EA and FIRE, so this is awesome!
One way the tool could be improved is by allowing to adjust for-tax deductibility of donations.
I’m not quite sure how the calculator would be adjusted, but the relevant metrics seem to be.
Maximum % of net/gross income that is tax-deductible if donated
% of donations that are tax-deducible
The distinction between if it applies to net or gross income might be necessary, because countries differ to the specification of tax-deductibility of donations.
Maybe most relevant excerpt for the forum (taken from 01:08:45, might contain some mistakes):