SAFE (Simple Agreement for Future Equity)

A contractual right to receive equity in the future, typically at the next priced round. Created by Y Combinator in 2013 to simplify early-stage fundraising. Not debt. No interest, no maturity date.

Why it matters

SAFEs have become the default instrument for pre-seed and seed fundraising because they are fast, cheap, and founder-friendly. A typical SAFE is just five pages long and requires minimal legal fees compared to a priced round that can cost $10,000 to $50,000 in legal work. Because SAFEs are not debt, they do not accrue interest or have a maturity date that forces repayment. This means founders avoid the pressure of a ticking clock that comes with convertible notes.

However, SAFEs still represent a claim on future equity, so every SAFE you issue will dilute your ownership when it converts. Founders who issue multiple SAFEs at different caps without modeling the combined dilution often discover at Series A that they have given away far more of the company than they realized. Understanding how SAFEs stack is critical for long-term cap table health.

The shift to post-money SAFEs in 2018 was a significant improvement for predictability. With a post-money SAFE, you know exactly what percentage each investor will own at conversion. With the old pre-money SAFEs, the dilution from each instrument depended on all the other instruments outstanding at conversion — a much harder calculation. See our full SAFE explainer for more.

How it works

When an investor buys a SAFE, they give the company cash now in exchange for the right to receive shares later, usually when the company raises a priced round (like a Series A). The SAFE will specify a valuation cap, a discount rate, or both, which determine how many shares the investor gets at conversion. For example, if an investor puts in $500,000 on a SAFE with a $5 million cap, and the Series A values the company at $10 million, the investor converts at the $5 million cap price, effectively getting twice as many shares per dollar as the Series A investors.

Y Combinator publishes standard SAFE templates (post-money and pre-money versions) that most startups use without modification. The post-money SAFE, introduced in 2018, makes dilution math simpler because the investor's ownership percentage is known at the time of investment. If you raise $1 million on a $10 million post-money cap, that investor will own exactly 10% at conversion, and all dilution comes from the founders' side.

At a change of control (acquisition) before a priced round, SAFE investors typically receive the greater of their original investment amount or their equity equivalent at the acquisition price. This gives SAFE investors downside protection in small exit scenarios while allowing them to participate in large ones.

History and origin

The SAFE was created by Y Combinator attorney Carolynn Levy and YC partner Kirsty Nathoo in late 2013, released publicly in December of that year. Before the SAFE, convertible notes were the standard early-stage fundraising instrument. Convertible notes had the advantage of being faster than priced rounds but the disadvantage of being debt instruments that accrued interest, had maturity dates, and required more legal negotiation than founders wanted at the earliest stages.

YC designed the SAFE to be as simple as possible — a single-document instrument that could be signed and closed in days rather than weeks, with minimal legal cost. They also made the templates freely available under Creative Commons licensing, so any startup could use them. Adoption was rapid; within a few years, SAFEs had become the dominant early-stage instrument in the US startup ecosystem.

In October 2018, YC revised the SAFE to a post-money structure in response to widespread confusion about how pre-money SAFEs diluted founders when multiple SAFEs were stacked. The post-money SAFE fixed the investor's ownership percentage at the time of investment, making dilution transparent and predictable. Today, the YC post-money SAFE is effectively the industry standard for US pre-seed and seed fundraising.

Frequently asked questions

What is a SAFE?

A SAFE (Simple Agreement for Future Equity) is a financial instrument used in early-stage fundraising that gives an investor the right to receive equity in the company at a future date, typically when a priced funding round occurs. SAFEs are not debt — they carry no interest rate and have no maturity date. They were created by Y Combinator in 2013 to replace the convertible note as the standard early-stage fundraising instrument.

How is a SAFE different from a convertible note?

Both SAFEs and convertible notes are pre-equity instruments that convert into shares at a future round. The key differences: convertible notes are debt with an interest rate and a maturity date that can force repayment. SAFEs have neither. SAFEs are also simpler and have fewer terms to negotiate. See our detailed comparison in convertible notes vs. SAFEs.

What is a valuation cap in a SAFE?

A valuation cap is the maximum valuation at which a SAFE converts into equity. It protects early investors by ensuring they receive a minimum ownership stake regardless of how high the company's valuation grows. For example, if a SAFE has a $5M cap and the Series A values the company at $20M, the SAFE investor converts at $5M — getting four times more shares per dollar than Series A investors.

What is the difference between a pre-money and post-money SAFE?

In Y Combinator's original (pre-money) SAFE, the investor's ownership at conversion depended on all other convertible instruments outstanding at the time — making dilution hard to predict. In the 2018 post-money SAFE, the investor's ownership percentage is fixed at the time of investment (investment ÷ valuation cap). This makes dilution modeling simpler and more transparent for founders.

When does a SAFE convert to equity?

A SAFE typically converts to preferred equity at the next priced funding round (e.g., a Series A). It can also convert or pay out at a change of control (acquisition). If the company is acquired before a priced round, SAFE investors typically receive either their investment back or their pro-rata equity equivalent — whichever is greater — as specified in the SAFE agreement.

What discount rate does a SAFE have?

Some SAFEs include a discount rate (e.g., 20%) in addition to or instead of a valuation cap. The discount gives the SAFE investor shares at a lower price than the Series A price. For example, with a 20% discount and a Series A price of $2.00/share, the SAFE investor converts at $1.60/share. The investor uses whichever mechanism (cap or discount) gives them more shares.

Is a SAFE dilutive to founders?

Yes. Every SAFE issued represents a future claim on the company's equity. In a post-money SAFE, the dilution to founders is fixed at the time of investment. Multiple SAFEs stack — if you issue several SAFEs at different caps, the combined dilution can be significant. Founders should model the total cap table impact of all outstanding SAFEs before issuing new ones, and track them carefully in a cap table management tool.

Learn more

• SAFE notes explained
• Convertible notes vs. SAFEs: which is better?
• What is a cap table?
• Cap table management guide
• Should you raise VC?

Related terms

• Convertible Note
• Valuation Cap
• Discount Rate
• Dilution
• Pre-Money and Post-Money Valuation
• Priced Round
• Pro-Rata Rights