A SAFE feels painless when you sign it — money in, no shares issued, no immediate dilution. The dilution is real, it's just deferred: it lands all at once when the SAFE converts at your next priced round. Knowing how to calculate it in advance is the difference between a clean fundraise and an unpleasant surprise on your ownership percentage. Here's the mechanism, step by step, with a worked example.
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A SAFE (Simple Agreement for Future Equity) isn't shares — it's the right to receive shares at the next priced round. So on the day you sign, your cap table doesn't change and nobody is diluted. But at conversion, the SAFE turns into shares at a price set by its valuation cap or discount, and those new shares dilute everyone who was already on the cap table. The lower the effective conversion price, the more shares the SAFE holder gets — and the more you're diluted.
Two terms determine how many shares a SAFE converts into. The valuation cap is the maximum company valuation at which the SAFE converts — if you raise above it, the SAFE holder still converts as if the company were worth only the cap, which gives them a lower price per share and more shares. The discount gives them a percentage off the round price instead. When a SAFE has both, the investor gets whichever produces the lower price — and therefore more shares and more dilution for you.
The conversion formula
Conversion price = min(cap ÷ pre-round fully-diluted shares, round price × (1 − discount)). SAFE shares = SAFE investment ÷ conversion price. Your new % = your shares ÷ total shares after all SAFEs and the new round convert.
Say you own 8,000,000 of 10,000,000 shares (80%) and you raised a $500,000 SAFE with a $5,000,000 post-money valuation cap. You now raise a priced round at a $10,000,000 pre-money valuation. Because the round is above the cap, the SAFE converts at the cap. Watch how the SAFE holder's slice — and your dilution — falls out of the numbers.
| Step | Calculation | Result |
|---|---|---|
| Pre-round shares | Existing fully-diluted | 10,000,000 |
| SAFE conversion price | $5,000,000 cap ÷ 10,000,000 shares | $0.50 / share |
| SAFE shares issued | $500,000 ÷ $0.50 | 1,000,000 |
| SAFE holder ownership | 1,000,000 ÷ 11,000,000 (before round) | ~9.1% |
| Your ownership after SAFE | 8,000,000 ÷ 11,000,000 | 72.7% (down from 80%) |
Simplified: the priced-round investor's new shares dilute everyone further on top of this.
Doing this by hand for one SAFE is manageable; doing it for a stack of SAFEs with different caps and discounts, all converting at the same round, is where spreadsheets break. Equafy models pre-money and post-money SAFEs on your real cap table and shows the exact dilution before you sign a term sheet — every SAFE converting simultaneously, reconciled against the round and the option pool, with a full audit trail.
Work out the SAFE's conversion price (the lower of the valuation cap divided by pre-round shares, or the round price minus the discount), divide the SAFE investment by that price to get the shares issued, then divide your existing shares by the new total share count to see your reduced percentage.
No — a SAFE issues no shares when signed, so there's no immediate dilution. The dilution happens all at once when the SAFE converts to shares at your next priced round.
A lower valuation cap means a lower conversion price, which means the SAFE holder receives more shares for the same investment — and therefore dilutes existing shareholders more. If you raise above the cap, the SAFE converts as if the company were worth only the cap.
They all convert at the same priced round but at their own conversion prices based on individual caps and discounts, so their dilution stacks. Modeling them together is essential — Equafy's cap table simulator handles simultaneous SAFE conversions and shows the cumulative dilution.
Equafy models every SAFE and note — cap, discount and all — on your live cap table, so you see exactly how a priced round dilutes you before you sign.
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