Every guide below takes one mechanic that quietly decides how much your SAFE stack dilutes you, and works it end to end with real numbers — the same arithmetic the RoundEconomics engine runs. No hand-waving, no black box. Start with the first one if SAFEs are new to you.
ownership = principal ÷ cap. A $1M SAFE at a $10M cap, worked to the exact share count — and who pays for it.
The investor takes the lower price. Two rounds — one where the cap wins, one where the discount does — side by side.
One most-favoured-nation SAFE ties your hands on every SAFE you sign after it. Worked with a two-instrument stack.
Post-money percentages add. Two 5% SAFEs are 10%, not ~5% — the single most under-counted mechanic in a seed stack.
A pool created in the pre-money dilutes you and your SAFEs, not the new investor. The points it costs, made visible.
No cap means the percentage isn't fixed until the round prices. How to bound it before you sign the next one.
Simple interest accrues to conversion, then the note converts like a SAFE. A $250k note at 6% for 14 months, worked out.
Your real dilution depends on a pre-money you don't control yet. Model it as a spread, not a single false-precise number.
The free estimate on the home page runs the same core engine in your browser. The $390 report converts your real SAFE stack across bear / base / bull scenarios, with per-instrument MFN / discount resolution and a stacking-warning map.
Try the free estimate Get the report — $390