SAFE vs Convertible Note: Which Should Founders Use?

You've got a verbal commitment from an angel investor or a seed fund. Now comes the question: what instrument do you use to close the deal? For most pre-seed and seed rounds, the answer is either a SAFE (Simple Agreement for Future Equity) or a convertible note. Both let you raise money without setting a valuation right now. But they work differently in ways that will affect your cap table, your relationship with investors, and your future fundraising. Here's what you need to know.

What a SAFE Actually Is

A SAFE is a one-page (or close to it) agreement invented by Y Combinator in 2013. The investor gives you money today. In return, they get the right to receive equity later, when a "priced round" happens (typically your Series A or Seed with a lead investor who sets a valuation). The SAFE isn't debt. There's no interest rate, no maturity date, and no obligation to repay. It's a contract that converts into shares at a future financing event.

The current standard is the YC post-money SAFE, which was updated in 2018. The critical word here is "post-money." Under the old pre-money SAFE, investors didn't know exactly what percentage of the company they were buying because it depended on how much total money was raised on SAFEs. The post-money SAFE fixes this: the valuation cap is applied to the post-money capitalization, so each investor knows their exact ownership percentage from day one.

What a Convertible Note Actually Is

A convertible note is a loan that converts into equity. It has an interest rate (typically 2-8%), a maturity date (usually 18-24 months), and converts at a discount or cap when a qualifying financing round occurs. Because it's technically debt, if the maturity date arrives without a conversion event, the investor can theoretically demand repayment. In practice, this almost never happens — most notes get extended or converted — but it creates an awkward dynamic.

Convertible notes were the standard instrument for early-stage fundraising before SAFEs existed. They're still widely used, particularly outside Silicon Valley, in markets where investors are more conservative, or when the investor specifically wants the debt protections that a note provides.

Valuation Caps: The Price That Isn't a Price

Both SAFEs and convertible notes typically include a valuation cap. This is the maximum valuation at which the investment will convert into equity. If the cap is $10 million and your Series A prices at $20 million, the SAFE or note converts at the $10 million valuation — giving the early investor twice as many shares as a Series A investor per dollar invested.

The cap is the single most important economic term in either instrument. It effectively sets a ceiling on the price the early investor pays. A $6 million cap on a post-money SAFE means the investor is buying roughly their investment amount divided by $6 million in ownership. If they invest $500K on a $6M cap, they're getting about 8.3% of the company.

What cap should you set? There's no formula. It depends on your stage, traction, market, and negotiating leverage. At pre-seed with just an idea, caps of $4-8 million are common. With some product and early users, $8-15 million. With real revenue and growth, $15-25 million or higher. The cap should reflect a reasonable discount to what you expect your next priced round valuation to be.

Discounts: The Other Conversion Mechanism

A discount gives the early investor a percentage reduction on whatever price the next round sets. A 20% discount means if the Series A is priced at $10/share, the note or SAFE converts at $8/share. Most instruments have both a cap and a discount, and the investor gets whichever produces more shares (i.e., whichever is more favorable to them).

Standard discounts range from 15-25%, with 20% being the most common. On the current YC post-money SAFE, the standard template doesn't include a discount — it uses a cap only. Many founders use this as the default. If an investor pushes for both a cap and a discount, that's a negotiation point where you can push back.

MFN and Pro-Rata: Two Clauses Worth Understanding

MFN stands for Most Favored Nation. It's a clause in some SAFEs (particularly uncapped SAFEs or SAFEs with a high cap) that says: if you issue a subsequent SAFE with better terms, this investor automatically gets those better terms too. It's a protection against the early investor getting a worse deal than someone who comes in later. YC's standard SAFE includes an MFN provision on the no-cap version.

Pro-rata rights give the investor the option to invest in your next round to maintain their ownership percentage. This sounds minor, but it matters. If a seed investor has pro-rata rights and your Series A lead doesn't want to accommodate them, it creates friction. On the flip side, having committed follow-on investors can be a positive signal. Most YC SAFEs include a pro-rata side letter for investments over a certain threshold.

SAFE vs. Note: A Direct Comparison

Speed and simplicity: SAFEs win. A standard YC SAFE is 5 pages, requires minimal negotiation, and can close in days. Convertible notes require more legal work, have more terms to negotiate, and typically cost $2,000-$5,000 more in legal fees.

Founder-friendliness: SAFEs win again. No maturity date means no ticking clock. No interest means no accruing cost. No debt on your balance sheet means cleaner financials. The post-money SAFE's simplicity also means fewer opportunities for investors to slip in aggressive terms.

Investor protection: Notes win. The debt structure gives investors more leverage. The maturity date creates urgency. Interest accrual means the conversion amount grows over time. Some institutional investors, particularly outside major tech hubs, simply won't invest on a SAFE because their LPs expect debt protections.

Tax treatment: It depends. SAFEs have some ambiguity in tax treatment that notes don't. Consult a tax attorney if this is a concern, particularly for international investors.

When to Use Each Instrument

Use a SAFE when: you're raising from angels or seed funds in the Silicon Valley ecosystem, you want speed and simplicity, you're raising from multiple investors at different times (rolling close), or when you're a YC company (it's the default). The YC post-money SAFE with a valuation cap is the most founder-friendly standard instrument available.

Use a convertible note when: your investors specifically require it, you're raising outside the US where SAFEs aren't well understood, the investor is a bank or institution that needs a debt instrument for regulatory reasons, or when the maturity date pressure actually serves your interests (as a forcing function to hit milestones).

The Hidden Risk of Stacking SAFEs

One warning that applies to both instruments but is especially common with SAFEs: don't stack too much convertible capital. Because SAFEs are so easy to close, some founders keep raising on SAFEs well past the seed stage. They'll have $3-4 million in outstanding SAFEs before doing a priced round. When those all convert, the dilution can be shocking.

A good rule: keep your total SAFE and note capital to under 20-25% of your expected next-round valuation. If you expect to raise a Series A at $20 million pre-money, try to keep total convertible instruments under $4-5 million. Beyond that, the conversion dilution starts to create problems for both you and future investors.

The instrument you choose matters less than understanding exactly what it means for your cap table. Model the conversion scenarios before you sign. Know what your ownership looks like after conversion at different valuations. The best fundraising instrument is the one whose implications you fully understand.