What does this SAFE really cost you?

A SAFE, a Simple Agreement for Future Equity, is the one-document instrument Y Combinator published in 2013. The investor pays now and receives shares at the next priced round. Since 2018 the standard is the post-money SAFE: the amount divided by the valuation cap is the share of the company the investor is promised, and other SAFEs do not dilute it. Priced rounds do.

Today: amount divided by cap, so $500K on a $10M cap is 5.00%. At the first priced round the SAFE converts and is diluted by that round's new money and its option pool top-up, as the YC post-money SAFE user guide describes; the founders absorb the rest. Every later round dilutes all holders by its new money plus its pool top-up.

The model uses the cap as the conversion price, the usual case. Discounts, pro rata rights, liquidation preferences and rounds after the Series A are not modelled. This is the default model of the detailed calculator, so both tools give the same figures.