Convertible Notes Explained: Terms Every Founder Should Know

What Is a Convertible Note?

A convertible note is a short-term debt instrument that converts into equity at a future financing round. Instead of negotiating a valuation at the seed stage (when the company may be too early to value accurately) the investor lends money that will convert into shares when a priced round (typically Series A) occurs. The investor receives a discount or valuation cap (or both) as compensation for taking the early risk.

Convertible notes became popular because they are simpler and cheaper to execute than priced equity rounds, typically a short document rather than the full set of equity financing papers.

Key Terms

Every convertible note includes several critical terms:

• Principal amount: The amount invested
• Interest rate: Interest accrues and converts alongside the principal. This is largely a legal formality rather than a meaningful economic term
• Maturity date: When the note comes due if no conversion event occurs
• Valuation cap: The maximum valuation at which the note converts. If the Series A is at $20M but the cap is $10M, the note converts at $10M, giving the investor twice the shares
• Discount rate: A percentage discount to the Series A price, set in the note. If the Series A is priced at $2/share with a 20% discount, note holders convert at $1.60/share

Cap vs. Discount

Most notes include both a cap and a discount, with the investor receiving whichever produces more shares (the more favorable conversion). In practice:

• The cap protects the investor if the Series A valuation is very high
• The discount protects the investor if the Series A valuation is at or below the cap
• From the founder's perspective, the cap has the greatest potential dilutive impact

Negotiation tip: if investors push for a low cap, negotiate for a lower discount rate (or vice versa) to balance the overall economics.

Potential Pitfalls

Convertible notes create several risks that founders should understand:

• Stacking problem: Multiple convertible notes with different caps create a complex conversion waterfall that can result in more dilution than founders expect
• Maturity without conversion: If no priced round occurs before maturity, the investor can technically demand repayment, though in practice this usually leads to a renegotiation or extension
• Hidden dilution: Because notes do not show up on the cap table until conversion, founders may underestimate their actual dilution
• Misaligned incentives: Very low caps can create situations where early investors are indifferent to the Series A valuation because their conversion price is already locked in

When to Use Convertible Notes

Convertible notes work best for small seed rounds where the speed and simplicity of execution matter more than precise valuation. For larger rounds or situations where the valuation is reasonably clear, a priced round may be more appropriate because it provides transparency and avoids the complexity of future conversion calculations.