Methodology

FounderMath calculators use deterministic formulas documented on each tool page. The calculators are designed for educational planning, not exact legal or cap-table administration.

Formula standards

• Use plain formulas that can be inspected and tested.
• Show important assumptions near calculator results or explanatory sections.
• Prefer conservative simplified models over pretending to model every legal document variation.
• Reject or warn on impossible inputs such as negative investments or 100% investor ownership.

Formula index

• Pre/post-money valuation: post-money valuation = pre-money valuation + investment; investor ownership = investment ÷ post-money valuation.
• SAFE cap vs discount: compare cap price and discount price; the lower simplified conversion price controls the modeled share count.
• Convertible note conversion: conversion amount = principal + simple accrued interest; qualified financing price = qualified financing pre-money valuation ÷ pre-round fully diluted shares; compare discount and valuation-cap prices when provided and model conversion at the lowest available price.
• Founder dilution: founder ownership after financing is modeled from founder shares divided by the post-financing fully diluted share count.
• Option pool top-up: solve the new option shares needed to reach a target post-closing pool percentage, with separate simplified treatment for pre-money and post-money pool handling.

Review standards

Each calculator should have known test cases, edge-case tests, browser smoke tests, mobile checks, and visible last-reviewed dates. Finance-adjacent material is reviewed for disclaimers, unsupported claims, and language that could sound like legal, tax, accounting, investment, or fundraising advice.

Limitations

Startup financing terms vary by document, jurisdiction, capitalization definition, option-pool treatment, and negotiation. SAFE and convertible-note calculations in particular can change materially based on exact terms. FounderMath outputs are estimates for understanding concepts.

See Sources for source categories used when validating terminology and assumptions.

Last reviewed July 21, 2026.