Calculate the resulting AFR of a fuel mixture, using up to three fuels and what percentage of fuel is in the mix. Choosing a fuel fills in its stoichiometric AFR and density. You can change either one, and changing a value sets that row to Custom.
The blend's stoich AFR is the mass-weighted average of each fuel's stoich AFR. Each fuel needs its own amount of air per pound, so mass is what counts. Volume percentages are converted to mass using each fuel's density. Pump E85 and race fuels vary by batch and season, so use the supplier's numbers if you have them.