For most angels writing small checks, a standard post-money SAFE is the better default: it is short, widely used, and fixes your ownership at the valuation cap. A convertible note protects the investor more, because it is debt with interest and a maturity date, which matters most when the company may never raise a priced round.
Founders usually choose the instrument, so the angel's real decision is whether to accept it, what to negotiate inside it, and when to push for something different. This is the comparison from the investor's side of the table. The points below are the ones that change what you actually own.
What is the difference between a SAFE and a convertible note?
Both are ways to invest before a company sets a price per share. Both convert into the shares sold in the next priced round, usually at a better price than the new investors pay. The difference is what they are while they wait.
Legal form. A convertible note is a loan. A SAFE (simple agreement for future equity) is a contract for shares later and is not debt. Y Combinator published the SAFE in 2013 and standardized on the post-money version in 2018.
Interest. A note accrues interest, and the interest normally converts into extra shares alongside the principal. A SAFE pays no interest.
Maturity. A note has a maturity date, after which the holder can ask to be repaid or negotiate a conversion. A SAFE has no end date; it waits until a priced round, a sale or a shutdown.
Price terms. Both can carry a valuation cap, a discount or both. YC's current US forms are a cap with no discount, a discount with no cap, and an uncapped MFN (most favoured nation) version.
Pro rata. On the standard SAFE, the right to invest in later rounds lives in a separate pro rata side letter. A note includes it only if the note purchase agreement says so.
The complete guide to SAFE notes and the guide to convertible notes explain each instrument on its own; the rest of this article is about choosing between them.
How the same check converts under each
A simple illustration, with round numbers chosen for the arithmetic rather than taken from any deal. You put in $50,000.
On a post-money SAFE with a $10 million cap, your stake just before the priced round is fixed: $50,000 divided by $10 million, or 0.5%. Other SAFEs the company sells later dilute the founders, not you. The priced round then dilutes everyone, you included.
On a convertible note with the same cap and 6% simple interest that converts after 18 months, $54,500 converts: the principal plus $4,500 of interest. That is about 9% more shares than the SAFE for the same cash. Many notes use a pre-money cap, though, which means your percentage also depends on how much other money converts alongside you. Ten other notes at the same cap shrink everyone's slice in a way a post-money SAFE does not.
That trade is the heart of it. The post-money SAFE gives the investor a predictable number. The note gives a slightly larger number that is harder to predict. When several rounds of SAFEs stack up at different caps, the founders absorb that dilution first, and the explainer on dilution for angel investors shows how it reaches you once the priced round lands.
What changes in practice for the angel?
The paper differences matter less than these practical ones.
If the company shuts down. A note holder is a creditor and ranks ahead of shareholders. The standard SAFE pays out ahead of common stock, alongside other SAFEs and preferred stock, and behind creditors, including note holders. In practice, a company that winds down rarely has much cash left, so the note's priority is worth less than it looks on paper.
If the company never raises a priced round. This is where the two diverge most. A profitable company that stops raising can leave a SAFE outstanding for years, with nothing to convert into and no date that forces a conversation. A note's maturity date gives holders a reason to talk: most notes get extended or converted at maturity rather than repaid, but the date itself is leverage.
If the company is sold before converting. Under the standard post-money SAFE, you receive the greater of your money back or what your shares would be worth had you converted at the cap. Notes vary: some pay principal plus interest, some a multiple, some convert. Read that clause before signing.
Taxes. Ask a tax adviser two questions before investing. First, how is the accrued interest on the note treated, since it may count as income before you receive any cash? Second, when does the Section 1202 (QSBS) holding period start? For a note it generally starts at conversion, because debt is not stock. For a SAFE the answer is less settled, and advisers differ.
Cost and speed. A SAFE is a few pages that most lawyers and founders already know. Notes are longer and less uniform, which means more reading for you and more legal fees for the company.
Which is better for the angel?
As advice rather than a rule:
Accept a standard post-money SAFE when the company plans to raise a priced round within the next couple of years and your check is a small part of the round. Spend your energy on the cap, not the instrument.
Ask for a note, or a SAFE with a conversion trigger, when the business could become profitable without a priced round, such as a services-heavy or niche software company. That is where an open-ended SAFE hurts most.
Ask for the pro rata side letter if you want to follow on. The article on whether pro rata rights matter to angels covers when that ask is worth making.
Request a summary of every outstanding SAFE and note, with caps, before you sign. Stacked convertibles are the most common surprise at the first priced round.
Read any modified form line by line. A "standard SAFE" with edits to the conversion or liquidity clauses is no longer standard.
Outside the US, check the local norm. UK angels claiming SEIS or EIS relief typically use advance subscription agreements, because a SAFE does not fit those schemes.
The guide to negotiating a term sheet as an angel covers which terms a small check can realistically move. More explainers on deal terms are in the angel investing section.
Frequently Asked Questions
Q:Is a SAFE riskier than a convertible note for an angel?
Slightly, in two situations: a shutdown, where note holders rank ahead of SAFE holders, and a company that never raises a priced round, where a SAFE has no maturity date to force a decision. In the outcome angels invest for, a priced round followed by growth, the two end up close.
Q:Do convertible notes actually get repaid at maturity?
Rarely. Most early-stage companies don't have the cash, and investors usually prefer to extend the maturity date or convert into equity. The value of the maturity date is the conversation it forces, not the repayment.
Q:Does a post-money SAFE protect me from dilution?
Only until the priced round. It fixes your ownership against other SAFEs sold before that round, because their dilution falls on the founders. The priced round's new shares, and any option pool increase in that round, dilute you like every other shareholder.
Q:What is an MFN SAFE?
An uncapped SAFE with a most favoured nation clause: it has no cap or discount of its own, but if the company later sells SAFEs on better terms, you can take those terms. It suits very early checks, though you are trusting that the later terms will be reasonable.
Q:Can I convert my existing SAFE into a convertible note?
Only if the company agrees to amend or replace it, which is unusual. It is easier to agree on the instrument before the money moves than to change it afterwards.