Article
Fundraising

SAFE vs. Convertible Notes — Which Is Better for Founders

2026.05.05·9 min·OPENSEED

The two structures used most often in seed rounds are the SAFE and the convertible note. Both defer setting a valuation now and convert into preferred stock at the next round, but they differ in maturity, interest, and legal character. This guide compares the two structures and lays out, from a founder's perspective, which one makes sense in which situation.

Intro.

#The SAFE — A Simple Promise Invented by Y Combinator

The SAFE (Simple Agreement for Future Equity) is an investment instrument Y Combinator introduced in 2013. It's a promise to take money now and convert it into preferred stock at the next qualified financing round — a promise of future equity, not debt. With no maturity date and no interest, its terms are refreshingly simple.

  • Legal character — not debt, no maturity date
  • Interest — none
  • Conversion trigger — the next qualified financing round (e.g., Series A)
  • Key terms — valuation cap, discount rate, and the Most Favored Nation (MFN) clause
TIP
As of 2018, Korean law made it difficult to recognize a pure SAFE as formal paid-in capital, so a modified 'SAFE-style contract' was used instead; since then, relevant regulations and market practice have evolved, widening how it can be used. Wherever you operate, always have a lawyer review the specific terms before signing.
02

#Convertible Notes — Debt With Maturity and Interest

A convertible note is debt — the investor is repaid principal plus interest at maturity, or holds the right to convert into preferred stock at the next round instead. In Korea, it's used less often than SAFEs at the seed stage, but its strength is that it's a structure clearly recognized under commercial law.

  • Legal character — debt (a bond/note)
  • Interest — typically 1-5% annually, accrued and paid at maturity
  • Maturity — typically 12-24 months, at which point it either converts or gets repaid
  • Key terms — cap, discount, interest rate, and maturity date
주의
A convertible note's maturity date is a real latent risk. If the next round hasn't closed by then, the company owes principal plus interest — and if cash is short, that obligation can push the company toward insolvency.
03

#Key Comparison

ItemSAFEConvertible Note
Legal characterA promise of equity (not debt)Debt (a note)
MaturityNone12-24 months
InterestNoneTypically 1-5%
Conversion triggerA qualified financing roundA qualified financing round, or maturity
Founder riskLow (no maturity pressure)High (repayment obligation at maturity)
Investor protectionWeakerStronger (creditor status)
Contract complexityLowMedium
04

#Valuation Cap and Discount — Terms Common to Both

Both SAFEs and convertible notes rely on two core variables to determine the price at which they convert into preferred stock at the next round: the cap and the discount. When both apply, whichever is more favorable to the investor is the one that's used.

VariableDefinitionExample
Valuation CapThe maximum company valuation applied at conversionCap of ₩5B → even if Series A prices at ₩10B, conversion happens on a ₩5B basis
DiscountA discount applied to the next round's price20% discount → converts at 80% of the Series A price
MFNAutomatically matches better terms given to a later SAFEProtects investors in concurrently issued SAFEs

Set the cap too low, and even strong growth in company value means a disproportionate share flows back to the seed investor, driving up dilution at later rounds. Some structures use only a discount with no cap, but in the Korean market, the cap is standard.

05

#From a Founder's Perspective — Which One Is Better

SituationRecommended StructureWhy
Series A clearly expected within 12 monthsEither SAFE or convertible note worksThe short conversion window means the risk is roughly equal either way
Series A uncertain, 18+ months outSAFE recommendedA note's maturity date brings repayment risk
Investor insists on creditor statusA convertible note is unavoidableEmphasizes investor protection
Typical domestic angel or seed fundA SAFE-style structureSimple, closes quickly
Strategic investor requiring guaranteesA convertible noteLegal certainty
TIP
Issue too many SAFEs over time, and dilution can spike sharply when they all convert at Series A. A common rule of thumb is to keep the total amount of SAFEs outstanding under 25% of your expected Series A valuation.
Summary.

#Self-Check: A Founder's Checklist

  1. Is your next qualified round (e.g., Series A) expected within 12 months, or 18+ months out?
  2. Is the investor insisting on creditor status via a convertible note, or are they open to a SAFE?
  3. Have you reviewed all three terms — cap, discount, and MFN?
  4. If you've issued multiple SAFEs or notes, have you simulated your remaining ownership after they all convert at Series A?
  5. If it's a convertible note, do you have a plan — starting six months before maturity — for repayment, refinancing, or conversion?
  6. Have you had local counsel review the agreement and flag any deviations from the standard template?
CTA
OpenSeed's CFO and Legal agents automatically simulate how your SAFEs or notes convert at Series A, model cumulative dilution, and flag maturity risk. It's included free alongside your business plan review during the current beta.
광고

Simulate Your SAFE or Note Conversion Alongside Your Business Plan

Our CFO agent quantifies cumulative dilution and flags maturity risk.

🔒 Free during beta · your submission isn't saved

Start Free AI Feedback →

관련 AI 피드백 서비스.

AI 피드백
사업계획서 AI 추천
AI 피드백
IR 덱 피드백
AI 피드백
IR 자료 검토
RELATED · Same categoryFundraising
Why Seed-Stage VCs Weigh 'Team Risk' So Heavily — Persuasion Strategies for Solo Founders, Non-Technical CEOs, and Teams With No Domain Experience2026.07.10 · 8 minDue Diligence and Data Room Prep — What VCs Demand After the Term Sheet2026.06.30 · 9 minHow to Use Follow-Up Emails After an Investor Pass to Stay in the Relationship and Land the Next Round2026.06.30 · 8 minThey Were Speaking Different Languages — Why Great Technology Fails When It Doesn't Translate2026.06.29 · 8 minThe Shareholder Consent and Board Resolution Documents Founders Must Prepare Before Series A2026.06.28 · 8 min
← Back to Discovery