YC Founder Ownership Calculator

First, it applies any pre-YC option pool dilution to founders (default 0%). Then it assigns YC’s $125k post-money SAFE as a fixed 7% ownership share right away. For the MFN safe, it approximates conversion using the best available terms implied by your follow-on post-money valuation (if you enter a follow-on round); otherwise it uses the same valuation framework as a simplified proxy.

This tool uses a simplified SAFE conversion model: the MFN safe converts based on the next round’s valuation inputs, but real conversion can vary due to negotiated terms, caps/floors, and legal mechanics. It also assumes option pools are created immediately and excludes liquidation preferences, pro-rata rights, vesting/refresh grants, bridge rounds, taxes, and any additional SAFEs beyond YC. Treat the results as an educational estimate, not legal advice.

Use a positive pre-YC valuation for meaningful percentages, keep the option pool between 0% and 30%, and don’t set a follow-on valuation lower than the follow-on raise amount. If you set follow-on raise amount to 0, the calculator will treat the follow-on as not applicable and expects the follow-on post-money valuation to be 0 too. If modeled founder ownership drops below 50% (or 25%), the tool flags “significantly/heavily diluted” so you can sanity-check the scenario.

If you enter a follow-on raise amount but forget the valuation (or vice versa), the calculator’s validation will prevent inconsistent results. If you set founder count above 1, it will split founder ownership into equal shares by default (custom splits are available in advanced mode) and ensure the split totals 100%. If option pool is high (e.g., >20%), expect materially higher dilution and the calculator will display a warning.