Fundraising calculator
Convertible Note Calculator
Estimate how a startup convertible note could convert in a qualified financing using explicit assumptions for principal, simple interest, discount, valuation cap, and share count.
Quick answer: convertible note conversion formula
Conversion amount = principal + simple accrued interest. Qualified financing price = qualified financing pre-money valuation ÷ pre-round fully diluted shares. Discount price = qualified financing price × (1 - discount). Cap price = valuation cap ÷ applicable capitalization. The simplified model converts at the lowest available price.
What this calculator includes
- Principal and optional simple interest.
- Discount conversion price when a discount is included.
- Valuation-cap conversion price when a cap is included.
- Qualified financing price per share from a priced-round pre-money valuation and pre-round fully diluted shares.
- Estimated note shares and implied ownership before new priced-round money.
Important limitations
Actual convertible note conversion depends on the signed note and financing documents, including qualified financing thresholds, interest compounding or non-compounding treatment, capitalization definitions, option-pool handling, valuation-cap mechanics, discount mechanics, maturity provisions, and conversion order. This page intentionally uses simplified transparent math rather than pretending to reproduce every document variation.
Educational-use disclaimer: FounderMath is for educational planning only. It is not legal, tax, accounting, investment, securities, financial, or fundraising advice. Do not use it as a substitute for reviewing actual documents with qualified counsel and advisors.
Related tools
Fundraising hub · SAFE Conversion Calculator · Valuation Cap vs Discount · Pre/Post-Money Calculator
FAQ
How does this convertible note calculator estimate conversion shares?
It adds simple interest to principal, calculates qualified financing price from pre-money valuation and shares, compares discount and valuation-cap prices when provided, then uses the lowest modeled conversion price to estimate note shares.
Does this replace the convertible note document?
No. Convertible note conversion depends on the signed note, qualified financing definition, capitalization definition, interest treatment, valuation cap, discount, maturity provisions, and conversion order. This calculator is educational only.
Last reviewed July 22, 2026. See Methodology and Sources.