Well, whatever split you take-- you'll have a vesting period (2-4 years). So, another way to look at it is this: After 4 years (or whatever the vesting period

Well, whatever split you take-- you'll have a vesting period (2-4 years). So, another way to look at it is this: After 4 years (or whatever the vesting period is), how much of a discrepancy will there be between the total value you've created and the total value he has created? How much discrepancy will there be in risks you've taken and the salaries you've missed? With your 3 month head start, that'd be 51 man-months vs. his 48 man-months. At the end of the day, there's no formula here, and you trying to calculate in assorted risks and values really isn't going to come up with an correct number-- all it's going to do is give you a feeling that you went thru appropriate motions. But, I can say that 99 times out of a hundred, the first 3 man months of a business are really not the most critical months... And it honestly sounds like you're over-estimating the value you've created and the risks you've eliminated. Also, from the way you're describing it-- you're not looking to bring this guy on as a partner or co-founder-- you're describing a decidedly non-partner relationship. It sounds more like you're looking for someone who walks and talks like an employee, but is happy to take no salary and a minority stake. You really haven't eliminated that much risk, though you've clearly accomplished a good amount in 3 months... But you really don't even know what sort of business you're creating yet and whether the market wants it. I'd go 55-45 or 60-40 with each of you having a 4 year vesting period (yours could have a 1 year acceleration due to your head start).