What Is a Convertible Note? Convertible Note vs. SAFE, Explained

What is a convertible note?

A convertible note is a short-term loan a startup takes from an investor that's designed to convert into equity later, usually at the next priced funding round, instead of being repaid in cash. Unlike a SAFE, a convertible note is a real debt instrument: it accrues interest, carries a maturity date, and technically obligates the company to repay the principal if it never converts. Founders reach for a note when they want SAFE-like speed but need terms a debt investor — often a bank-adjacent fund or an investor uncomfortable with SAFE's newer, more one-sided structure — will actually sign.

The instrument predates the SAFE by decades and is still the default outside Silicon Valley, in markets where investors are more conservative about giving up creditor protections. It solves the same problem a SAFE solves — nobody wants to negotiate a full valuation for a $150K pre-seed check — but it keeps the investor's fallback right to be repaid if the company never raises a priced round.

How a convertible note works: interest, maturity, cap, and discount

A convertible note carries four core terms. The interest rate (commonly 4-8% annually) accrues over the life of the note and — critically — usually converts into extra shares at the priced round rather than being paid in cash. The maturity date (typically 18-24 months out) is the deadline by which the note must either convert or be repaid; it's the one mechanic a SAFE doesn't have at all.

The valuation cap and discount work exactly as they do on a SAFE: the cap sets the maximum price the note converts at even if the next round prices higher, and the discount (typically 15-25%) gives the note holder a percentage off the new round's share price. Whichever term produces more shares for the investor is the one that applies at conversion.

Convertible note vs. SAFE: the difference

The difference founders feel first is legal status: a convertible note is debt, a SAFE is not. That single fact cascades into everything else — a note appears as a liability on the balance sheet, can trigger default if it matures unconverted, and gives the holder creditor rights in a wind-down. A SAFE has none of that; it simply waits to convert or expires worthless if the company shuts down.

In practice, most US seed-stage founders now default to a SAFE because it's faster, cheaper to paper, and carries no repayment risk. Convertible notes still show up when an investor's fund mandate requires a debt instrument, when a bridge is being raised between priced rounds under time pressure, or in markets where local law or investor habit hasn't caught up to the SAFE.

When founders choose a convertible note over a SAFE

Reach for a note, not a SAFE, in three situations. First, when your investor's fund can only write debt checks — some corporate VCs and family offices are structurally barred from holding non-debt instruments. Second, when you're raising an emergency bridge between priced rounds and existing investors want the seniority and repayment protection debt gives them if the round doesn't materialize. Third, when you're raising outside the US, where SAFEs carry less legal precedent and local investors default to notes.

Otherwise, default to a SAFE. It's cheaper to paper (often a one-page document vs. a note's multi-page loan agreement), it doesn't put a repayment clock on your cap table, and nearly every accelerator and seed fund template assumes it.

What happens when a convertible note matures unconverted

This is the scenario notes create that SAFEs simply cannot: the maturity date arrives, the company hasn't raised a priced round, and the note is technically due and payable. In practice, almost nobody actually calls the loan on an early-stage startup with no cash to repay it — foreclosing kills the note holder's own upside. What actually happens is a renegotiation: the note gets extended, converted at a fixed price the investor and founder agree on, or rolled into whatever bridge financing comes next.

Still, "nobody actually enforces it" is not a plan. A maturing, unconverted note is leverage in the investor's hands during a renegotiation, and founders who ignore the date until it's overdue negotiate from a weaker position than founders who start the extension conversation two or three months out.

Testing note terms in the simulation

Founder Runway runs a 20-turn arc from Pre-Seed to Series A, and the instrument you pick to raise early capital shows up later as founder ownership and investor trust, not just cash in the bank. Raise a bridge on a note with a low cap and watch what your stake looks like once it converts at the next priced round — then run it again with a straight SAFE and compare.

It's a faster way to feel the tradeoff between the flexibility debt gives you today and the ownership it quietly costs you later than reading about it ever will be.

Conclusion

A convertible note is debt that converts to equity — it carries interest and a maturity date a SAFE doesn't have, and gives the investor repayment rights if the company never raises a priced round. Most US pre-seed and seed rounds now default to a SAFE for its speed and lack of repayment risk; notes persist where a fund's mandate requires debt, where a bridge needs seniority, or outside markets where SAFEs are standard. Model either instrument's conversion the day you sign it — the free dilution calculator on this site shows exactly how a round changes founder ownership.