Educational only — not investment, legal or tax advice.
A SAFE (simple agreement for future equity) is the most common way to raise a first round in the US. There is no valuation negotiation in the usual sense, no board seat, and the documents are short. That convenience is real. The catch is that every SAFE is a promise of shares later, and founders often only see the full cost when all of them convert at once.
How a SAFE works
An investor gives you money now. In return, they get the right to shares when you raise a priced round (typically your Series A). The SAFE usually has a valuation cap, which sets the most expensive price at which their money can convert, and sometimes a discount to the priced round.
Y Combinator’s standard post-money SAFE, the version most US startups use, measures the investor’s ownership after all the SAFE money is counted. YC’s own guide describes the benefit as being able to calculate immediately and precisely how much of the company has been sold. In practice: a $1M SAFE with a $10M post-money cap buys about 10% of the company, before the next round.
Worked example: three SAFEs, one Series A
Example, hypothetical numbers, simplified: ignores the option pool and discounts.
| SAFE | Amount | Post-money cap | Ownership bought |
|---|---|---|---|
| Angel round | $1M | $8M | 12.5% |
| Pre-seed extension | $1M | $10M | 10.0% |
| Seed | $2M | $16M | 12.5% |
| Total | $4M | 35.0% |
Before any priced round, the founders have already sold 35% of the company. Each SAFE looked small on its own.
Now the company raises a Series A in which new investors buy 20% of the company. Everyone else is diluted proportionally:
| Holder | Before Series A | After Series A |
|---|---|---|
| Founders | 65% | 52% |
| SAFE holders | 35% | 28% |
| Series A investors | 0% | 20% |
So the founders go from 100% to 52% across their first four financings, and in a real round the option pool usually takes several more points. Many founders discover this the week their Series A closes.
Why SAFEs surprise founders
- They stack silently. There is no cap table update until conversion, so it is easy to lose track.
- Different caps, different prices. Each SAFE converts at its own cap, so early, cheap SAFEs cost more ownership than they seem to.
- The option pool lands on top. Series A investors usually ask for a refreshed pool, which dilutes existing holders further.
How to stay in control
- Keep a pro-forma cap table that shows every SAFE as if it had already converted. Update it every time you sign one.
- Decide your total pre-Series A dilution budget before you start raising, and stop when you hit it.
- Prefer fewer, larger SAFEs at a consistent cap over many small ones on drifting terms.
- Read side letters. Pro rata rights and most-favoured-nation clauses can change the maths later.
From the investor’s side of the table. Structuring equity and quasi-equity rounds is a core part of my work, and my master’s thesis at Nova SBE studied how another non-priced instrument, revenue-based finance, affects the startup ecosystem. A SAFE is one of several tools that postpone the valuation conversation. Whichever one you use, model what it converts into before you sign it.
The short version
A post-money SAFE tells you exactly how much you sold. Add them up every time you sign one, because the total is what your Series A will be built on.
Sources
Written by Fabian Cisneros. Educational only — not investment, legal or tax advice. See the full disclaimer.
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