Convertible Note Conversion Math for Venture Investors

A convertible note is a debt instrument that may convert into equity during a qualified financing under its negotiated terms. The investor's resulting position depends on principal, interest accrual, conversion discount or valuation cap, share capitalization and any special provisions.

A SAFE and a convertible note can both support early fundraising, while the note may also involve maturity, repayment and interest provisions. Compare the executed instruments and the financing they reference rather than applying one universal conversion formula.

Calculate the balance that converts

Assume a $500,000 note with 8% simple annual interest converts after 18 months. If the agreement provides that all accrued interest converts, the accrued interest is $60,000 and the converting balance is $560,000. This illustration assumes an exact 1.5-year period and no compounding, partial repayments, fees or default interest.

Accrued simple interest = $500,000 × 8% × 1.5 years = $60,000; converting balance = $560,000

Apply a negotiated discount

Assume new preferred shares cost $2.00 each in a qualified financing and the note converts at a 20% discount. Under this illustration, the conversion price is $1.60 and the note receives 350,000 shares.

$2.00 × (1 − 20%) = $1.60 per conversion share; $560,000 ÷ $1.60 = 350,000 shares

The resulting ownership fraction depends on the fully diluted shares after conversion and issuance of the new-money securities. A number of shares without the corresponding capitalization denominator cannot establish the investor's final percentage.

How a valuation cap changes the result

A valuation cap may produce a lower conversion price when the priced round valuation is higher than the negotiated cap. The agreement defines the cap price and the share population used for the calculation. The final model must apply those definitions alongside any discount provision.

For a separate simplified cap-price case, a cap calculation producing $1.25 per share would convert a $560,000 balance into 448,000 shares. The $1.25 price is an illustrative result, with its derivation dependent on contractual capitalization definitions.

$560,000 converting balance ÷ $1.25 assumed cap-based price = 448,000 shares

Review the maturity and repayment provisions

A maturity date can trigger notice, negotiation, extension or a repayment right under the instrument. Qualified-financing thresholds, change-of-control provisions and non-qualified financing mechanics may create additional outcomes. Counsel should interpret the signed note and relevant law.

Model all outstanding convertible securities together

When a company has several notes, SAFEs or warrants, conversion share counts can interact with the new priced round and option pool. A fund should request one pro forma capitalization model that reconciles each instrument. SAFE conversion math supplies related assumptions for non-debt instruments.

The NVCA model legal documents offer useful reference materials for priced equity transactions, though they do not replace note-specific executed provisions. Maintain the final calculations with counsel and the cap-table provider.

How Treto supports the diligence work

Treto's Diligence workspace can keep convertible instruments, financing history and questions about the cap table connected to the investment process. The transaction team's approved model determines the conversion and share issuance.

Questions investors ask

Does accrued note interest always convert into shares?

Interest treatment is governed by the executed note. Some terms convert the principal and accrued interest, while others handle interest or repayment differently. Investors should confirm accrual conventions, maturity date and the amount included in the conversion calculation.

How do investors compare a note's cap and discount?

Calculate the possible conversion price under each applicable contractual method using the same financing assumptions. Then apply the actual clause governing the conversion result. The valuation-cap capitalization definition and any investor side letter can materially change the share count.