SAFE Note Calculator
Enter your SAFE investment, valuation cap and discount alongside the priced round terms to see which term wins at conversion and roughly what ownership percentage the SAFE buys.
Reviewed by the CalcCafe editorial team · Last updated 18 July 2026 · How we test our tools
Example
Suppose you invested $500,000 on a SAFE with a $5,000,000 valuation cap and a 20% discount, and the company later raises a priced round at an $8,000,000 pre-money with $2,000,000 of new money. The discount would let you convert at 8,000,000 × 0.8 = $6,400,000, but the cap is lower, so the SAFE converts at $5,000,000 — the valuation cap wins. Ownership at conversion ≈ 500,000 ÷ 5,000,000 = 10%. Had the round priced at a $5.5M pre-money instead, the discounted value ($4.4M) would beat the cap and the discount would win.
How it works
A SAFE (Simple Agreement for Future Equity) converts to shares when a priced equity round happens. The investor gets the better of two terms: the valuation cap (a maximum conversion valuation) or the discount (a percentage off the round price). This tool computes the discounted valuation = pre-money × (1 − discount%), takes the lower of that and the cap as the effective conversion valuation, and estimates ownership = investment ÷ effective valuation — the post-money SAFE convention where the cap directly implies an ownership floor (investment ÷ cap). Simplifications to know: real conversions are computed per share against the company capitalization defined in the SAFE, multiple SAFEs interact with each other and the option pool, and the priced round then dilutes everyone further. Zero inputs return 0 rather than errors.
Good to know
The biggest fork in SAFE-land is pre-money versus post-money. Y Combinator introduced the original pre-money SAFE in 2013 and switched its standard documents to the post-money SAFE in 2018. Under a post-money SAFE, ownership is locked at investment ÷ post-money cap regardless of how many other SAFEs the company stacks afterward — a $500K SAFE on a $5M post-money cap is 10%, full stop. Under the older pre-money SAFE, every additional SAFE diluted all the earlier SAFE holders together, so nobody knew their ownership until the priced round. The post-money version moved that uncertainty onto founders, which is exactly why investors prefer it and why founders should model dilution before signing.
Cap and discount are alternative prices, not additive ones: at conversion the investor takes whichever single term produces more shares, never both combined. The cap wins when the company appreciates well past it (the common case for a successful startup — and why caps, not discounts, drive most SAFE economics), while the discount wins in flat or modest rounds where the pre-money never clears the cap-adjusted threshold. Uncapped SAFEs with only a discount exist but are mostly reserved for hot deals; a 20% discount is the customary ceiling, and 10-20% the normal range.
Dilution stacking is the silent killer of SAFE-heavy cap tables. Each post-money SAFE carves its percentage out of the founders, and the percentages add: $250K at a $2.5M cap (10%) plus $500K at a $5M cap (10%) plus $1M at an $8M cap (12.5%) already commits 32.5% of the company before the Series A investors and the option pool take their share. Founders routinely discover at the priced round that they own 15-20 points less than they assumed. Keep a running SAFE ledger — total ownership sold equals the sum of investment ÷ cap across all post-money SAFEs — and treat every new SAFE as the equity sale it really is.
Two clauses deserve attention beyond the headline terms. The MFN (most-favored-nation) provision — standard in YC’s uncapped MFN SAFE — automatically upgrades an earlier SAFE to the terms of any better SAFE issued later, protecting early believers from being leapfrogged. Pro-rata side letters give SAFE investors the right to invest again in the priced round to maintain ownership; under post-money SAFEs this is a separate optional side letter rather than a built-in right. Neither changes the arithmetic here, but both change who can own what after the Series A, so read them before you model the round.
Frequently asked questions
Does a SAFE investor get both the cap and the discount?
No — cap and discount are alternative conversion prices, and the investor receives whichever single term produces more shares at the priced round. In successful companies the cap usually wins because the round prices well above it; discounts tend to matter only in flat or modest rounds.
What is the difference between a pre-money and post-money SAFE?
The post-money SAFE (YC's standard since 2018) fixes the investor's ownership at investment divided by the post-money cap, no matter how many other SAFEs follow — dilution from later SAFEs falls on the founders. The older pre-money SAFE left all SAFE holders diluting each other, so ownership was unknowable until the priced round.
How much ownership does a SAFE actually buy?
For a post-money SAFE, roughly investment divided by the lower of the cap and the discounted round valuation — a $500K SAFE at a $5M cap is about 10% at conversion. The priced round itself then dilutes that stake further, and exact numbers depend on the per-share math in the full cap table.
Is my data uploaded anywhere?
No — this calculator runs entirely in your browser. Your investment and valuation figures never leave your device, and the page keeps working offline once loaded. It is completely free with no sign-up.
People also ask
What happens to a SAFE if the company never raises a priced round?
The SAFE simply sits unconverted. Standard YC SAFEs convert or pay out on a priced equity round, a liquidity event (acquisition or IPO), or dissolution — there is no maturity date or interest, unlike a convertible note. In an acquisition the investor typically gets the greater of their money back or conversion value.
What is an MFN clause in a SAFE?
A most-favored-nation provision automatically upgrades an earlier SAFE to match better terms the company later gives another SAFE investor — for example a lower cap. It is the defining feature of YC's uncapped MFN SAFE and protects the earliest checks from being leapfrogged.
How do multiple SAFEs dilute founders?
Under post-money SAFEs the ownership percentages simply add: three SAFEs at 10% each commit 30% of the company before the priced round and option pool take their cut. Founders should keep a running total of investment divided by cap across every SAFE outstanding.
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Sources & references
These tools follow our methodology and provide educational estimates only — verify important figures with a qualified professional.