In 2018, Y Combinator replaced its original pre-money SAFE with a post-money SAFE. Most founders never noticed. The change was a meaningful shift in how dilution flows through the cap table.
If you are raising on SAFEs in 2026, you almost certainly are using post-money SAFEs. Understanding the difference between the two is essential to understanding what you are actually selling and how it may affect future startup fundraising rounds.
The Pre-money SAFE
Under the original pre-money SAFE, the valuation cap referred to the company’s pre-money valuation. The SAFE investor’s ownership percentage depended on how much new money was raised at conversion and how many other SAFEs converted at the same time. The math was complex, but the effect was that the founder and the SAFE investor shared dilution from each subsequent SAFE or note.
The Post-money SAFE
Under the post-money SAFE, the cap refers to a post-money valuation that includes the SAFE itself and all other convertibles converting at the same time. The investor’s ownership percentage at conversion is fixed by formula: SAFE amount divided by post-money cap. A $500,000 investment at a $5,000,000 post-money cap gives the investor 10%, and that 10% is protected until the next priced round.
What that means in practice: every additional SAFE issued dilutes the founders, not the existing SAFE holders.
A Worked Example
Assume founders own 100% of the company and raise on the following post-money SAFEs:
- SAFE 1: $500,000 at a $5,000,000 post-money cap. Investor 1 is guaranteed 10%.
- SAFE 2: $500,000 at a $6,000,000 post-money cap. Investor 2 is guaranteed approximately 8.33%.
- SAFE 3: $1,000,000 at an $8,000,000 post-money cap. Investor 3 is guaranteed 12.5%.
Combined SAFE ownership at conversion: approximately 30.83%. Founder ownership before any priced round dilution or option pool expansion: 69.17%.
Under a pre-money SAFE structure, the same dollar amounts and caps would have produced a different, and usually more founder-friendly, outcome because subsequent SAFEs would have diluted earlier SAFE holders as well as founders.
The Practical Takeaway
Post-money SAFEs are the market default. Most investors will not accept a pre-money SAFE without a meaningful concession somewhere else. But founders should model their cap table on a fully diluted, post-conversion basis before signing each new SAFE.
Stacking three or four post-money SAFEs without a model is one of the more common ways founders arrive at a Series A with less ownership than they expected, and less leverage to negotiate future venture capital and angel investor rounds.
If you are raising on multiple SAFEs, build the cap table forward. Otherwise, the math will surprise you at the worst possible moment
Avisen Legal’s startup and growth counsel team helps founders model pre- and post-money SAFE cap tables before they sign. If you are stacking SAFEs and want a clear-eyed look at where you will land at Series A, get in touch.
Frequently Asked Questions about Pre-money and Post-money SAFEs
What is the difference between a pre-money SAFE and a post-money SAFE?
A pre-money SAFE calculates investor ownership based on the company’s valuation before the SAFE investment and other converting securities are fully accounted for. A post-money SAFE fixes the investor’s ownership percentage based on the SAFE amount divided by the post-money valuation cap.
Why do post-money SAFEs usually dilute founders more?
Post-money SAFEs lock in each SAFE investor’s ownership percentage until the next priced round. When the company issues additional SAFEs, that dilution generally falls on the founders rather than earlier SAFE holders.
How do you calculate ownership under a post-money SAFE?
The basic formula is the SAFE investment amount divided by the post-money valuation cap. For example, a $500,000 SAFE at a $5,000,000 post-money cap equals 10% ownership before the next priced round.
Are post-money SAFEs the market standard?
Yes. Post-money SAFEs are the current market default for many pre-seed and seed-stage financings. Founders should assume investors may expect a post-money SAFE unless the parties negotiate a different structure.
Should founders model SAFE dilution before signing?
Yes. Founders should model all outstanding SAFEs, option pool changes, and expected priced round dilution before signing another SAFE. A simple cap table model can reveal whether the founder ownership outcome still supports the company’s long-term financing strategy.
Can a company use both pre-money and post-money SAFEs?
It is possible, but mixing forms can make cap table modeling more complicated. Founders should understand how each instrument converts and how the combination may affect ownership, control, and future financing negotiations.
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