SAFE notes are simple agreements for future equity with no interest or maturity date, making them founder-friendly. Convertible notes are debt instruments that accrue interest and must be repaid or converted by a maturity date, creating risk. The key decision factors are your tolerance for this maturity date risk and the preferences of your target investors.
Key takeaways
- Choose SAFEs for speed and simplicity; they are not debt and have no maturity date.
- Understand that a convertible note's maturity date is a major risk if you can't raise.
- Model every SAFE and note to understand true dilution from the valuation cap.
- Use the "post-money" SAFE to avoid surprise dilution from multiple funding rounds.
- Never sign any financing document without review from an experienced startup lawyer.
- Standardize on one instrument per round to keep your cap table clean.
The Only Difference That Matters
Let's cut to the chase. A convertible note is debt . A SAFE is not.
This is the single most important distinction. Because it's debt, a convertible note has an interest rate and a maturity date . This means if you don't raise a priced round (a Series A) within a set period (usually 18-24 months), the investor can demand their money back, plus interest. For a cash-burning startup, this is a crisis.
A SAFE (Simple Agreement for Future Equity) has no interest rate and no maturity date. It can sit on your cap table forever, only converting to equity when you raise a priced round. It removes the ticking clock, which is an enormous advantage for a founder.
SAFE Notes: The Founder-Friendly Default
Y Combinator created the SAFE in 2013 to be a simple, fast, and founder-friendly alternative to convertible notes. Think of it as a warrant—a contract giving the investor the right to buy stock in a future financing round based on terms agreed upon today.
Key Terms in a SAFE
Valuation Cap: The most important term. This sets the maximum valuation at which the investor's money converts into equity. If you grant a SAFE with a $10M cap and later raise your Series A at a $20M valuation, the SAFE investor's money converts as if the valuation were only $10M. This rewards them for their early risk with a better price. · Discount: A secondary way to reward early investors. It gives them a percentage discount (e.g., 20%) off the Series A share price. If a SAFE has both a cap and a discount, the investor gets whichever term gives them a better price (more equity). · MFN (Most Favored Nation): An MFN clause, without a cap or discount, promises the investor that they will receive the best terms of any future SAFE you issue. It essentially kicks the can on setting a price, and is best used for very early, small checks from friends and family before you have a lead investor setting terms.
Crucial Update: Pre-Money vs. Post-Money SAFEs
This is a non-obvious point that trips up many founders. The original SAFEs (pre-2018) were "pre-money" SAFEs. The current, standard YC documents are "post-money" SAFEs.
The Mistake: Using "pre-money" SAFEs and raising multiple small checks. Each new SAFE check effectively diluted the previous SAFE investors, creating complex, circular math to figure out who owned what. It also meant you, the founder, couldn't precisely know how much dilution you were taking on with each new check.
The Fix: The post-money SAFE calculates ownership based on a simple formula: the amount invested divided by the "company capitalization" (which includes all converting SAFEs). Each SAFE is self-contained. You know exactly how much of the company you are selling with each post-money SAFE. For a $500k check on a $10M post-money SAFE, you are selling exactly 5% of your company ($500k / $10M). Period.
Rule: Always use the latest post-money SAFE templates from Y Combinator. They are the market standard and prevent dilution surprises.
Convertible Notes: Debt with an Equity Upside
A convertible note is a loan. The investor lends you money, and the loan accrues interest. The goal isn't repayment in cash; it's for the principal and interest to convert into equity during your next priced round.
Key Terms in a Convertible Note
Valuation Cap & Discount: These work the same way as in a SAFE, setting the terms for how the debt converts to equity. · Interest Rate: Typically ranges from 4-8% per year. This interest accrues and is added to the principal that converts, giving the investor slightly more equity as a reward for the time their capital is at risk. · Maturity Date: The critical term. This is the date (e.g., 24 months from signing) when the note is due. If you haven’t raised a "Qualified Financing" (a priced round of a minimum size, e.g., $1M) by this date, one of three things happens: · The Good: You and the investors agree to extend the maturity date. · The Bad: The note converts to equity at a very low, pre-negotiated valuation (e.g., the valuation cap), resulting in massive dilution for founders. · The Ugly: The investor demands full repayment of the principal plus accrued interest. This can bankrupt a startup.
How the Math Really Works: A Head-to-Head Example
Let's say you're raising a $1M seed round. You then raise a Series A with a $20M pre-money valuation.
Scenario 1: $1M raised on a Post-Money SAFE with a $10M Valuation Cap.
The math is simple: $1M / $10M = 10%. · The seed investors will own 10% of the company right before the Series A investors put their money in. The dilution is clear and fixed from the start.
Scenario 2: $1M raised on a Convertible Note with a $10M Cap and 6% interest, maturing in 24 months.
Let's assume you raise the Series A exactly 24 months later. · The principal is $1,000,000. · The accrued interest over two years (simple) is $1,000,000 0.06 2 = $120,000. · The total amount converting is $1,120,000. · This converts at the $10M cap. So the investors get $1,120,000 / $10,000,000 = 11.2% of the company.
The interest on the note resulted in an extra 1.2% dilution. While not enormous in this case, the more significant risk remains the maturity date trigger, which doesn't exist with the SAFE.
Founder Playbook: Common Mistakes & How to Avoid Them
Using Pre-Money SAFEs: The #1 avoidable error. You create a "Schrödinger's cap table" where you don't know your own ownership until the Series A closes. Fix: Download and use the standard YC post-money SAFE. Period. · Ignoring a Short Maturity Date: You are implicitly betting your company on your ability to raise a priced round in 12-18 months. This is a bet you don't need to make. Fix: If an investor insists on a note, push for a 24-month maturity, and have a plan for what happens if you can't raise in time. · Not Modeling the Total Dilution: Founders often track dilution from the cap but forget that multiple SAFEs stack up. Raising $500k on a $10M cap, then another $500k on a $12M cap, then $1M on a $15M cap leads to cumulative dilution you need to sum up. Fix: Keep a simple spreadsheet. For each post-money SAFE, calculate (Investment Amount / Post-Money Cap). Sum these percentages to see your total pre-Series A dilution. · Giving Away Pro-Rata Rights Automatically: Most SAFEs come with a pro-rata side letter, granting the investor the right to maintain their ownership percentage in future rounds. For a strategic $500k investor, this is fine. For a $25k angel, it can create administrative headaches in a $20M Series B. Fix: Be thoughtful. You can set a minimum check size (e.g., >$100k) to qualify for pro-rata rights.
Decision Framework: Which Instrument Is Right For You?
Default to a SAFE if
You are raising a pre-seed or seed round. · You value speed, simplicity, and low legal fees. · Your investors are angel investors or VCs familiar with standard startup practices. · You want to avoid the pressure of a maturity date.
Consider a Convertible Note if
An investor you need insists on it (often a family office, non-tech investor, or a fund with specific mandates). · You are raising a "bridge" round between two priced rounds, where the debt structure and maturity date create a genuine incentive to close the next round quickly. · Even then, question if a SAFE wouldn't work better. The maturity date is a loaded gun.
How to Apply This This Week
Download the Documents: Go to Y Combinator's website and download the latest "Post-Money SAFE" templates. Read the one-page primer and the 5-page document itself. Understanding the mechanics is your job. · Build a Dilution Model: Create a simple spreadsheet with cells for: SAFE Investment Amount, Valuation Cap, and Your Founder Ownership. Calculate Dilution = Investment Amount / Valuation Cap. See how your ownership changes as you add more SAFEs. · Set Your Terms: Based on your stage, team, and traction, decide on your target valuation cap. For a typical pre-seed round, this might be $8M-$15M. Have a "walk-away" number in mind. · Draft a Closing Email: When an investor commits, your job is to make it easy to wire. Prepare a template email: "Great chatting today and excited to have you on board! As discussed, we're raising on a standard YC Post-Money SAFE. The terms are: $[Investment Amount] on a $[Valuation Cap] Post-Money SAFE. I've attached the signed SAFE for your records. You can find wiring instructions here [Link to instructions]. Please let me know if you have any questions. Thrilled to be partners."
Frequently asked questions
- What is a typical valuation cap for a pre-seed round?
- For a US-based pre-seed B2B software company, caps typically range from $8M to $15M. Earlier stage, pre-product companies will be at the lower end, while teams with strong traction or previous founder success can command the higher end.
- Does a SAFE note expire?
- No. A SAFE note has no maturity date or expiration. It remains in effect until a conversion event occurs (like a priced round or acquisition) or the company dissolves.
- What happens if a company is acquired before a priced round?
- Both SAFEs and convertible notes have provisions for this. Typically, the investor can choose to either convert their investment at the valuation cap and participate in the acquisition proceeds as a shareholder, or receive their original investment back (often 1x, sometimes more).
- Why do some investors still prefer convertible notes?
- Some traditional investors, family offices, or those less familiar with tech startup conventions prefer the downside protection of debt. As a creditor, they have a higher-ranking claim than SAFE holders if the company liquidates.
- Can I raise on multiple SAFEs with different caps?
- Yes, this is very common. You can raise from different investors at different times on SAFEs with unique valuation caps. This is a key benefit of using post-money SAFEs, as their math isolates each investment, preventing early investors from being diluted by later ones.
