[mpenn]

My understanding is that additional post-money SAFEs dilute solely common, whereas additional pre-money SAFEs dilute common and other pre-money SAFEs. So if you want to do a new round, by doing an equity round, you can dilute the post-money SAFEs with common. But if you do a 2nd post-money SAFE round, solely common gets diluted.

Since keeping cap flat is logistically / emotionally easiest for both sides to swallow, the founder dilution is worse under a "flat" scenario. In the pre-money world, if you did pre-money $10mm cap and raised $2mm, then later another $2mm at same cap, common would own ~71% (10 / 14) on conversion (assuming A is high enough). In post-money world, if you do $12mm cap and raise $2mm (so equivalent to old world in 1st round), then later raise another $2mm with same cap, common would own 67% (8 / 12). That's just 4 - 5%, but a real difference.

So I believe the incentive is higher to do an equity round to convert the post-money SAFEs so they can be a part of the dilution of the new round. Unless I am mistunderstanding how they'd convert or something else here. The math is complicated (which I guess is the whole point of why moving to post-money will improve founders' understanding).