Convertible Note Calculator Guide: How Startup Notes Work (2026)
Quick Answer
- *A convertible note is startup debt that converts to equity at your next priced round — it delays the need to set a valuation, which is why it’s used at the earliest stages
- *Key terms: Valuation Cap (maximum price investors pay per share), Discount Rate (10–20% reduction from the next round price), Interest Rate (5–8% accrued until conversion), Maturity Date (typically 18–24 months)
- *Investors benefit from converting at whichever gives more shares: the cap or the discount — whichever results in a lower effective price per share
- *SAFEs (Simple Agreement for Future Equity), popularized by Y Combinator, have largely replaced convertible notes at pre-seed because they’re simpler — no interest, no maturity date
What Is a Convertible Note?
A convertible note is a short-term loan that automatically converts into equity when the startup raises its next priced funding round. Instead of negotiating a company valuation right now — which is nearly impossible for a company with no revenue or traction — the valuation question gets deferred. The investor lends money today, and the math works itself out later.
According to Carta’s 2024 State of Private Markets report, convertible instruments (notes and SAFEs combined) accounted for approximately 60% of all seed-stage financings in the United States. At the pre-seed stage, that figure climbs above 80%. They are the dominant mechanism for early-stage startup fundraising.
The note has four core variables: a valuation cap, a discount rate, an interest rate, and a maturity date. Understanding how these interact is essential before signing any term sheet.
4 Key Terms in a Convertible Note (Cap, Discount, Interest, Maturity)
1. Valuation Cap
The cap is the most important term. It sets the maximum valuation at which the note converts to equity, regardless of what the next round prices at. If your startup raises a Series A at a $20M pre-money valuation but the note has a $5M cap, the noteholder converts as if the company is worth $5M — getting four times as many shares as investors in the priced round.
AngelList data shows that typical pre-seed caps range from $3M to $8M, while seed-stage caps commonly fall between $8M and $15M. Higher caps favor founders; lower caps favor investors.
2. Discount Rate
The discount gives the noteholder a percentage reduction off the next round’s share price. A 20% discount means the investor pays $0.80 for every $1.00 of share price at the Series A. Typical rates range from 10% to 25%, with 15–20% being most common.
The discount and cap work independently. At conversion, the investor uses whichever mechanism results in a lower per-share price — in practice, the cap almost always wins when there’s meaningful valuation appreciation between rounds.
3. Interest Rate
Because a convertible note is technically a loan, it accrues interest. Standard rates are 5% to 8% per year, simple interest. This interest doesn’t get paid in cash — it accrues and converts to additional equity alongside the principal. On a $200,000 note at 6% over 18 months, the investor would convert approximately $218,000 worth of note principal into shares.
4. Maturity Date
The maturity date is the deadline: if no priced round has occurred by this date, the note technically becomes due. Most notes have a maturity of 18 to 24 months. In practice, startups rarely repay notes at maturity — instead, both parties negotiate an extension or the note converts at a negotiated valuation. But the maturity date gives investors leverage if the company stalls.
How Conversion Works at the Next Round
The mechanics work like this: when your startup closes a priced round (say, a Series A), the note converts to equity on the same day at the most favorable price for the investor.
Conversion via Cap: Convert price = Cap ÷ Fully diluted shares at conversion
Conversion via Discount:Convert price = Series A price × {1 − discount rate}
The investor gets whichever price is lower (more shares for the same money).
| Scenario | Value |
|---|---|
| Note principal | $100,000 |
| Accrued interest (6%, 18 months) | $9,000 |
| Total converting | $109,000 |
| Valuation cap | $5,000,000 |
| Series A pre-money valuation | $15,000,000 |
| Series A price per share | $1.50 |
| Cap conversion price | $0.50 (5M ÷ 10M shares) |
| Discount conversion price (20%) | $1.20 |
| Investor uses | Cap ($0.50 — more shares) |
| Shares received | 218,000 |
Use our Convertible Note Calculator to run these numbers instantly with your own inputs.
Convertible Note vs SAFE: Key Differences
Y Combinator introduced the SAFE (Simple Agreement for Future Equity) in 2013 to simplify early-stage fundraising. SAFEs have a cap and discount like notes, but no interest and no maturity date. They are not debt — they’re a warrant-like instrument.
| Feature | Convertible Note | SAFE |
|---|---|---|
| Legal structure | Debt (loan) | Equity warrant |
| Interest rate | 5–8% annually | None |
| Maturity date | 18–24 months | None |
| Converts to equity | Yes (at priced round) | Yes (at priced round) |
| Valuation cap | Yes | Yes |
| Discount rate | Yes | Yes |
| MFN clause | Rare | Common (post-money SAFE) |
| Repayment risk | Yes (at maturity) | No |
| Most common stage | Seed bridge rounds | Pre-seed, seed |
| Investor preference | Institutional angels, VCs | Accelerators, angel syndicates |
According to Y Combinator, the post-money SAFE has become the standard instrument for YC companies and the majority of pre-seed rounds in Silicon Valley. The key difference in the post-money SAFE: the cap is applied to the post-money valuation (including the SAFE money), which makes dilution calculations more predictable for founders.
5 Investor-Friendly vs Founder-Friendly Terms to Negotiate
Not all convertible notes are created equal. Here are the terms that matter most at the negotiating table:
1. Valuation Cap (Most Critical)
Founder-friendly: High cap ($8M+), or uncapped note. Investor-friendly:Low cap ($3–5M). A low cap means investors get a dramatically larger ownership stake if the company grows. Push for the highest defensible cap you can justify based on comparable financings at your stage.
2. Discount Rate
Founder-friendly: 10–15% discount. Investor-friendly:20–25% discount. For most notes, the discount rate is secondary to the cap — negotiate the cap harder. That said, notes without caps (rare) make the discount rate the primary conversion mechanism.
3. Interest Rate
Founder-friendly: 5% or lower. Investor-friendly: 8%+. The practical impact is small on short notes ($100K at 6% for 18 months adds only $9K), but it compounds on larger notes. SAFEs avoid this entirely.
4. Maturity Date
Founder-friendly: 24 months, with automatic extension rights. Investor-friendly:12–18 months, with conversion or repayment at maturity. Always negotiate for the longest maturity you can get — 18 months sounds like plenty of time until it isn’t.
5. Pro-Rata Rights
Investor-friendly: Guaranteed right to invest in the next priced round to maintain ownership percentage. Many sophisticated angels and micro-VCs require pro-rata rights as a condition of investing. For founders, pro-rata rights complicate cap table management but are often a fair trade for early capital.
Key Statistics on Convertible Note Usage
- Convertible instruments (notes + SAFEs) accounted for ~60% of seed financings in 2024, per Carta’s State of Private Markets data
- The median pre-seed SAFE cap in 2024 was approximately $8M to $12M, up from $4–6M in 2019, reflecting valuation inflation in early-stage markets
- According to Crunchbase, the average pre-seed round size in 2024 was $750K to $1.5M — the typical range for convertible note financings
- Y Combinator’s standard deal is a $500K SAFE at a $1.7M post-money cap (as of the W24 batch), representing the most standardized convertible instrument in the industry
- AngelList Venture data shows that discount rates of 15–20% appear in the majority of seed-stage convertible notes with both cap and discount provisions
Run the conversion math for your raise
Calculate Convertible Note Conversion →Raising equity? Also try our Equity Dilution Calculator and SAFE Note Calculator
Frequently Asked Questions
What is a convertible note?
A convertible note is a short-term debt instrument used in startup fundraising. It starts as a loan and converts to equity (ownership shares) at a future priced fundraising round. The key benefit is that it allows early-stage startups to raise money without setting a valuation upfront, which is difficult to do accurately at the pre-seed or seed stage.
How does conversion work on a convertible note?
When your startup raises a priced round (Series A), the convertible note converts to equity. The investor gets shares at whichever price is lower: the valuation cap price or the discounted price. For example, if a $100,000 note has a $5M cap and a 20% discount, and the Series A prices at $1.50 per share, the cap gives $0.50/share while the discount gives $1.20/share — the investor converts at $0.50 (the better deal). Use our Convertible Note Calculator to model any scenario.
What is a valuation cap on a convertible note?
A valuation cap is the maximum valuation at which a convertible note converts to equity, regardless of how high the startup’s valuation is at the next priced round. If a note has a $5M cap and the startup raises a Series A at a $20M valuation, the noteholder converts as if the company is worth only $5M — getting 4x more shares than investors in the priced round. The cap is the most important term in a convertible note and the primary way early investors are compensated for taking on early risk.
What is the difference between a convertible note and a SAFE?
A SAFE (Simple Agreement for Future Equity), created by Y Combinator in 2013, is similar to a convertible note but simpler: it has no interest rate, no maturity date, and no debt component. A convertible note is technically a loan with an interest rate (typically 5–8%) and a maturity date (typically 18–24 months), which means the company owes money if no conversion happens. SAFEs have largely replaced convertible notes at the pre-seed stage because they’re cleaner for both sides. Convertible notes are more common in bridge rounds or when institutional investors prefer debt instruments.
What happens if a convertible note matures without converting?
If a convertible note reaches its maturity date without a qualifying financing event, the startup technically owes the principal plus accrued interest back to investors. In practice, founders usually negotiate an extension, convert the note at a negotiated valuation, or raise a priced round before maturity. Actual repayment is rare because startups typically don’t have cash to repay notes — but the maturity date gives investors leverage to negotiate if the company is struggling.
What is a typical discount rate on a convertible note?
Discount rates on convertible notes typically range from 10% to 25%, with 15–20% being the most common. The discount gives early investors a lower price per share at the priced round compared to new investors. For example, a 20% discount means the noteholder pays $0.80 for each dollar of share price at the next round. The discount rate and valuation cap work together — investors use whichever mechanism gives them more shares.