SAFE vs Convertible Note: Key Differences Explained

A SAFE (Simple Agreement for Future Equity) and a convertible note both let a startup take investment now and issue shares later, usually at the next priced round. The key difference is that a convertible note is debt, with an interest rate and a maturity date, while a SAFE is not debt and has neither. Both typically use a valuation cap, a discount or both to reward early investors, and both can create more dilution than founders expect if they are not modelled carefully.

How convertible instruments work

Early-stage companies often struggle to justify a precise valuation. Convertible instruments postpone that question. The investor hands over money today, and the instrument converts into the same type of shares that investors buy in a later priced round, usually on better terms to compensate for the earlier risk.

The two main levers are:

• Valuation cap: the maximum valuation used for conversion. If the next round is priced higher than the cap, the early investor converts at the cap.
• Discount: a percentage reduction on the price per share paid by the new investors in the next round, for example 20%.

When both exist, the investor normally gets whichever gives the lower price per share.

SAFE vs convertible note at a glance

Feature	SAFE	Convertible note
Legal nature	Contract for future equity	Debt (a loan)
Interest	None	Yes, usually accrues and converts into shares
Maturity date	None	Yes, triggers repayment, extension or conversion
Valuation cap	Common	Common
Discount	Common	Common
Repayment risk	Generally none	Possible at maturity, depending on terms
Paperwork	Short, standard templates (US)	Longer, more negotiation
Typical use	Pre-seed and seed, often in the US	Pre-seed and bridge rounds, many markets

The SAFE was popularised by Y Combinator as a simpler alternative to the convertible note. Over time, a post-money SAFE version became widespread; it fixes the investor's ownership percentage based on the cap, which makes dilution easier to understand but shifts it to the founders.

Worked example: a post-money SAFE converts

A startup has 1,000,000 founder shares. An angel invests €200,000 on a post-money SAFE with a €2,000,000 valuation cap and no discount.

What the cap means: the SAFE holder is promised €200,000 ÷ €2,000,000 = 10% of the company as it stands just before the next priced round (including the SAFE shares, but excluding the new money).

To hold 10% alongside 1,000,000 founder shares, the SAFE converts into about 111,111 shares (111,111 ÷ 1,111,111 = 10%).

A year later, the company raises a priced round of €1,000,000 at a €6,000,000 pre-money valuation, with the converted SAFE counted in the pre-money.

1. Pre-money share count: 1,111,111
2. Price per share: €6,000,000 ÷ 1,111,111 ≈ €5.40
3. New investor shares: €1,000,000 ÷ €5.40 ≈ 185,185
4. Total shares: about 1,296,296

Holder	Shares	Ownership
Founders	1,000,000	~77.1%
SAFE investor	111,111	~8.6%
New investor	185,185	~14.3%

The SAFE investor effectively paid about €1.80 per share against €5.40 for the new investor, which is the reward for investing earlier. You can check the priced round part with the post-money valuation calculator. A real round would usually also involve an option pool, which changes the numbers again.

What if there were three SAFEs?

With post-money SAFEs, each SAFE fixes its own percentage. Three SAFEs of €200,000 each at a €2,000,000 cap would claim 30% together, and that 30% comes entirely out of the founders' share before the priced round dilutes everyone further. This is why stacking SAFEs without a running cap table is dangerous.

Worked example: a convertible note converts

Now the same angel invests €200,000 as a convertible note with 6% simple annual interest, an 18-month maturity, a €2,000,000 pre-money valuation cap and a 20% discount. The priced round happens after 18 months at the same terms as above. This is simplified; real notes often define the share count used for the cap in more detail.

1. Amount converting: €200,000 + interest (€200,000 × 6% × 1.5 years = €18,000) = €218,000
2. Price via the cap: €2,000,000 ÷ 1,000,000 pre-money shares = €2.00
3. Price via the discount: round price × (1 − 20%). With a round price of roughly €5, the discounted price would be around €4, so the cap gives the lower price and applies.
4. Shares from conversion: €218,000 ÷ €2.00 = 109,000 shares

Two differences stand out. First, the interest converts into extra shares, so the note holder gets more for the same cheque. Second, if the company had not raised a round before maturity, the founders would have had to negotiate an extension, a conversion or, in the worst case, repayment.

Pros and cons for founders

SAFE

Advantages

• Fast and cheap to sign; the standard US templates are short
• No interest and no maturity date, so no repayment pressure
• Easy to raise from several angels at different times

Disadvantages

• Dilution is invisible until conversion, which makes it easy to over-raise
• Post-money SAFEs place all dilution from additional SAFEs on the founders
• Some investors and some jurisdictions are less familiar with the instrument

Convertible note

Advantages

• Familiar to many investors and legal systems
• Interest and maturity give investors comfort, which can make raising easier
• Works well for bridge rounds between two priced rounds

Disadvantages

• Debt on the balance sheet, which can matter for insolvency rules in some countries
• Maturity date creates a deadline and potential leverage for investors
• More terms to negotiate, so higher legal cost

When to choose which

Situation	Often a better fit
US company raising from angels, small cheques at different times	SAFE
Investor or market where notes are the norm	Convertible note
Bridge financing ahead of a planned priced round	Convertible note
You want to avoid any repayment risk	SAFE
You need clarity on ownership right away	Priced round instead of either
Company outside the US	Local equivalent, chosen with a lawyer

Many countries have their own versions. Convertible loan agreements are common in parts of Europe, and the UK uses advance subscription agreements in some situations. Tax and securities rules differ, so the "standard" choice depends on where your company is incorporated and where your investors are.

Step by step: raising on a convertible instrument

1. Decide the total you will raise this way. Set a ceiling so convertibles do not pile up.
2. Set the cap and discount. Base the cap on a valuation you would be comfortable with in a priced round, not the highest number someone will sign.
3. Model the conversion in a scenario with your expected next round, including an option pool. The funding dilution calculator helps you see what a priced round does after the convertibles are in.
4. Choose pre-money or post-money mechanics knowingly, and understand who carries the dilution.
5. Check side terms: most-favoured-nation clauses, pro-rata rights, information rights, and for notes, maturity and interest.
6. Keep a live cap table that shows the outstanding convertibles and their likely conversion. The basics are in cap table explained.
7. Get legal review in your jurisdiction before signing.

Common mistakes

Treating the cap as the company's valuation. The cap is a ceiling for conversion, not a valuation the market has agreed. Next-round investors will price the company on its merits.

Raising on many caps. Different caps for different investors make conversion hard to explain and can upset early backers.

Forgetting interest. On a note, interest converts into shares too. Over a long maturity, it adds up.

Ignoring the maturity date. If your next round slips, a note can turn into a negotiation at the worst moment.

Not modelling the priced round. Founders often discover the combined effect of convertibles, a pool shuffle and a new investor only when they see the closing cap table.

Where to go next

To understand how the valuation in the next round is set, read pre-money vs post-money valuation. For the bigger picture of when to use which instrument at which stage, see the startup fundraising guide.

This article is general information and not legal, tax or investment advice. Convertible instruments are treated differently across countries, so have a qualified lawyer and tax adviser review any agreement before you sign it.