Startup Equity Calculator

Startup equity calculator projects founder equity through multiple dilution rounds. Founders typically start with 100%, dilute 15-25% per major funding round. After 4 rounds: 100% × 0.8^4 = 41% remaining. After 6 rounds: 26%. Famous example: Travis Kalanick held ~10% Uber at IPO, Jeff Bezos held ~16% Amazon at IPO.

Example: founder starts 100% equity. Seed dilution 20%, Series A 20%, Series B 20%, Series C 20%. Final: 100 × 0.8 × 0.8 × 0.8 × 0.8 = 41%. At 100M exit: founder gets 41M. With same dilution but option pool refreshes (additional 10% per round): final equity 27% = 27M at exit. Option pools matter.

Dilution comes from three sources: (1) New investor shares in funding rounds, (2) Option pool refreshes (new shares for employees), (3) Convertible note conversions. Founders should track fully-diluted ownership (assuming all options/notes converted), not just current share count. Rule of thumb: target 25-30% founder equity at IPO across founding team.

Quick example

With initial equity of 100% and number of funding rounds of 4 (plus dilution per round of 20% and exit valuation of 100,000,000), the result is 40,960,000.00. Change any figure and watch the output shift — it's often more useful to see the pattern than to memorise the formula.

Which inputs matter most

You enter Initial Equity %, Number of Funding Rounds, Dilution Per Round %, and Exit Valuation. Not every input has equal weight. Adjusting one input at a time toward extreme values shows which ones move the result most.

What's happening under the hood

Final equity = initial × (1 - dilution per round)^rounds. Exit proceeds = final equity × exit valuation. The formula is listed in full below. If the number looks off, you can retrace the calculation by hand — that's the point of showing the working.

Where this fits in planning

This is a "what-if" tool, not a forecast. Use it to test ideas before committing: what happens if the rate is 2% lower than hoped, what happens if you add five more years. The value is in the scenarios you run, not the single answer you get from the defaults.

What this doesn't capture

Steady-rate math ignores real-world volatility. Actual returns are lumpy; sequence-of-returns risk matters most in drawdown; fees and taxes drag on compound growth; and behaviour changes in drawdowns can reduce outcomes below the projection. The number represents one scenario rather than a forecast.