A friend-to-friend guide · Post-money SAFE · YC 2018+ form

What does half a million dollars actually buy?

A SAFE — Simple Agreement for Future Equity — turns into shares only when the company raises a priced round. The math is short, the surprises are many. Move the inputs to see exactly how your investment becomes ownership, how it gets diluted at Series A, and what it pays back at exit.

After SAFE converts
5.00%
pre-Series A
After Series A closes
3.65%
your final ownership
Paper value at this round
$0.51M
1.02× at the Series A price

Three snapshots of the cap table

100% = the whole company
Stage 1
Today
Stage 2
SAFE converts
Stage 3
Series A closes
Founders
Option pool
SAFE holder (you)
New Series A investor

The lower price wins.

When your SAFE converts, you get shares at whichever effective price is lower: the cap price, or the discounted round price. Never both — even though you "have" both terms. Here's how today's inputs play out:

What the "post-money" in post-money SAFE really means

The "post-money" doesn't mean after the Series A money. It means after all SAFEs convert but before the Series A new money. So your $0.5M ÷ $10M cap = 5% is your slice at that moment — and it gets diluted again when Series A comes in. YC's own primer confirms this; it is the most-misread term in startup finance.

From a sheet of paper to a slice of a company.

Five steps. Watch how your percentage moves at each one.

What you walk away with, at $X exit.

Drag the slider to set an exit value. Numbers assume your SAFE has converted into a standard 1× non-participating preferred at Series A — the usual outcome.

$100M
Your payout
$3.65M
3.65% × $100M, after pref check
Return multiple
7.3×
on your $0.5M
IRR (5-yr hold)
48.6%
if exit happens in ~5 years

Where the exit money goes

What "1× non-participating preferred" means for you

At a priced round your SAFE converts into a flavor of preferred stock. On exit, every preferred holder picks the better of two options: take 1× their money back as liquidation preference, or convert and take their share of common. The preference only matters when the company sells for cheap — at good outcomes everyone just converts.

What first-time angels typically miss.

The most expensive mistakes friends-and-family angels make rarely come from the cap or the discount. They come from these:

most important"A cap means I own that fraction."

No: the cap defines your conversion price ceiling, not your final ownership. Your $0.5M ÷ $10M cap = 5% is only your share at one specific moment — right after the SAFE converts and right before Series A money lands. The Series A money and the option pool top-up immediately dilute you further. Headline percentage is a peak; what matters is what's left after the next round.

terminology trap"Post-money means after the round."

In post-money SAFE, "post-money" means after all SAFEs convert — not after the priced round. Y Combinator's own primer states this explicitly. Every first-time investor reads it the other way around.

silent killer"What if there's no Series A — ever?"

SAFEs have no maturity date. If the company chugs along on revenue and never raises a priced round, your SAFE just sits there. No interest accrues, no automatic conversion happens, and you cannot demand your money back. The single biggest under-appreciated risk for friends-and-family investors.

cap-table cascade"More SAFEs just dilute the founder."

In a post-money SAFE, this is true on paper — and that's the problem. Founders who stack four or five SAFEs at different caps wake up at Series A having given away 30–40%. The Series A lead then demands they re-vest, and the SAFE round gets renegotiated. As a SAFE holder you can be on either side of that conversation.

below the cap"What if Series A prices below my cap?"

Then the cap is irrelevant. You convert at the Series A price, the same as the new lead investor (minus your discount, if you have one). The cap is a one-way ceiling, not a floor. It does not protect against down rounds — only against up rounds.

acquisition"What if the company is bought before any round?"

You take the greater of: (a) your money back (the "cash-out amount"), or (b) what you'd get if the SAFE converted at the cap. So a $0.5M SAFE at a $10M cap in a $20M acquisition pays you the conversion path: $0.5M ÷ $10M × $20M = $1.0M. A $5M fire-sale pays you the cash-out: $0.5M back.

no rights"I'm an investor, so I have voting and info rights."

SAFE holders have almost no rights until the SAFE converts. No board seat, no voting, no formal information rights, no pro-rata (unless a side letter says otherwise — and the default post-money SAFE does not include one). For friends-and-family checks under $250K, you should expect none of these.

How this calculator works. Uses Y Combinator's post-money SAFE v1.1 conversion mechanics. SAFE conversion price = min(cap-implied price, discounted round price). Pool top-up is calculated pre-money and dilutes everyone who came in before Series A, including SAFE holders. Exit math assumes SAFE converts into 1× non-participating preferred at the SAFE's conversion price (the standard shadow-preferred treatment). All inputs are kept in $ millions for readability. This tool is for explaining mechanics, not for negotiating. Talk to a startup lawyer before signing anything — most issue mistakes that are visible in a tool like this are caught by them, and the ones that aren't visible are caught by the lawyer.

Things this tool does not model: stacked SAFEs at multiple caps (the most damaging real-world pattern for founders), MFN clauses, pro-rata side letters, QSBS / §1202 tax treatment, anti-dilution provisions in Series A preferred, and the participating-preferred or multiple-pref edge cases that occasionally appear in distressed deals.