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Convertible Note Calculator

Calculate convertible note conversion with interest

Principal Amount ($)

Interest Rate (% APR)

Note Date

Conversion Date

Valuation Cap ($)

Discount Rate (%)

Series A Terms

Pre-money Valuation ($)

Series A Investment ($)

Interest Calculation

Time Elapsed

12 months

Accrued Interest

$40,000

Total Converting

$540,000

Conversion Analysis

At Valuation Cap

$10,000,000 cap

4.14%

$1/share

At Discount

20% discount

2.63%

$2/share

Best Conversion

Using valuation cap

4.14%

540,000 shares

Post-Conversion Cap Table

Founders76.69%

Note Holders4.14%

Series A Investors19.17%

Post-money Valuation$25,000,000

Convertible Note vs SAFE

Convertible Note

• Accrues interest
• Has maturity date
• Is debt (can be repaid)
• More complex legal docs

SAFE

• No interest
• No maturity date
• Not debt (equity)
• Simple, standard docs

What is Convertible Note Calculator?

A convertible note calculator models debt-to-equity conversion for convertible promissory notes. Unlike SAFEs, convertible notes are actual debt instruments with interest rates, maturity dates, and optional conversion triggers. The calculator shows how principal plus accrued interest converts into equity at a future priced round.

How to use this calculator

1Enter the principal amount of the convertible note and the annual interest rate.
2Input the maturity date and the date you expect to close your priced round.
3Set the valuation cap and discount rate matching your note terms.
4Enter the anticipated Series A pre-money valuation to model the conversion.
5Review the converted principal plus accrued interest, effective per-share price, and resulting ownership for all parties.

Why this matters for founders

Convertible notes were the pre-SAFE standard for early-stage fundraising and are still common outside Silicon Valley and in bridge rounds. The debt nature adds complexity -- maturity dates, interest accrual, and default scenarios -- that founders must understand to avoid unpleasant surprises.

How to read the results

•Interest accrues on the principal (typically 2-8% annually) and converts into additional equity at the priced round, slightly increasing dilution beyond the principal amount.
•Maturity dates (typically 18-24 months) create a legal deadline by which conversion or repayment must occur -- missed maturities can trigger default provisions.
•Like SAFEs, convertible notes have valuation caps and/or discount rates that determine the conversion price.
•If the note matures without a priced round, you must negotiate an extension, conversion, or repayment with each note holder.

Industry benchmarks

Typical interest rates: 2-8% annual. Standard maturity: 18-24 months. Common discount: 15-25%. Valuation caps vary by stage similarly to SAFEs. Notes are more common in markets outside SF/NYC and for bridge financing between priced rounds.

Key terminology

📋Convertible Note 📝SAFE