Then make it real: put it in writing with vesting — typically 4 years with a 1-year cliff (you earn nothing if you leave in year one). Research finds ~73% of cofounder fallouts trace back to a poorly-set initial split, so have this conversation early.

Equal-weighted estimate. Adjust the factors to reflect your reality; consider a dynamic model (Slicing Pie) if contributions are still in flux. Not legal advice.