Convertible note calculator.

Model how your convertible note converts to equity at Series A — shares received, ownership %, and whether the discount or valuation cap gives you the better deal.

Why convertible notes exist.

Convertible notes are short-term debt that converts to equity at the next priced round — the standard seed instrument when the company is too early to price.

  1. 01
    Skip valuation negotiations.Convertible notes defer the valuation question until Series A — useful when nobody can credibly price the company yet.
  2. 02
    Faster, cheaper than priced rounds.No 409A required, shorter docs, lower legal fees. You can close a note in a week, not a quarter.
  3. 03
    Reward early risk.Discount + cap give early investors better terms than Series A buyers — fair compensation for going first.
  4. 04
    Stack carefully, though.Multiple notes with different terms make Series A cap tables ugly. Keep the terms consistent.

Calculate your conversion.

The amount of money you invested in the convertible note

Annual interest rate on the note (typically 2-8%) Typical: 2–8%

Discount from Series A price per share (typically 15-25%) Typical: 15–25%

Maximum valuation for conversion (optional but common)

Time from note issuance to Series A conversion

Pre-money valuation of the Series A round

Price per share in the Series A round

Total shares outstanding (fully diluted) at conversion

The five things in a convertible note.

  1. 01
    Principal.The cash invested. This is what converts to equity at Series A.
  2. 02
    Interest rate.Typically 2–8%. Accrues over time, lifting the amount that converts.
  3. 03
    Discount rate.15–25%. Investor pays a % less than the Series A price per share.
  4. 04
    Valuation cap.Maximum effective valuation at conversion. Protects investors if the company explodes in value.
  5. 05
    Maturity date.18–24 months. What happens if no Series A by then — extension, repayment, or forced conversion.

Convertible note vs. SAFE.

Convertible note

  • → Accrues interest (2–8%)
  • → Has a maturity date
  • → Counts as debt on balance sheet
  • → More complex legal terms

SAFE

  • → No interest
  • → No maturity date
  • → Not debt — cleaner cap table
  • → Simpler (Y Combinator template)

Both use the same discount/cap mechanics. The choice usually comes down to investor preference and how clean you want the cap table to look.

Common convertible note mistakes.

  1. 01
    No valuation cap — investor loses upside if the company explodes in value.
  2. 02
    Cap set too low — creates problems and cap-table mess at Series A.
  3. 03
    Ignoring the math — most founders haven't actually run dilution numbers before signing.
  4. 04
    Missing maturity clauses — what happens if no Series A in 24 months?
  5. 05
    Stacking inconsistent notes — multiple notes with different terms create cap table chaos.

Typical terms in 2026.

Interest rate2–8% (most common: 5%)
Discount rate15–25% (most common: 20%)
Valuation cap (seed)$3M–$10M
Maturity18–24 months
Conversion triggerQualified financing ($1M+ Series A)

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  3. Vesting Schedule Calculator

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Raised on convertible notes? Now you need to build.

Convertible notes buy you 12–18 months to prove the thesis. I help early-stage founders ship that proof — MVPs, dashboards, and customer-facing apps in Next.js and TypeScript.

Email me

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