Startup Dilution Calculator
How much of the company do existing shareholders keep after a priced round? Enter the round and choose whether the option pool is created before the money (the usual "option pool shuffle") or after.
The formulas
Post-money = Pre-money + Round size · New investor % = Round size ÷ Post-money
Pool in the pre-money (shuffle): existing holders keep 1 − investor % − target pool % (plus any existing pool counted in the target). Post-round shares = existing shares ÷ that fraction, Price = Post-money ÷ post-round shares. The effective pre-money for existing holders is Price × existing (non-pool) shares, i.e. the headline pre-money minus the value of the new pool.
Pool added after the round: Price = Pre-money ÷ pre-round shares; the pool increase then dilutes everyone, including the new investors.
Worked example
10,000,000 shares, $8M pre, $2M raise, 10% post-money pool in the pre-money: investors 20%, pool 10%, founders 70%; price $0.70; effective pre-money $7M. With the pool added afterwards: price $0.80, founders 72%, investors 18%, pool 10%.
How much dilution is normal per round?
Commonly cited ranges are roughly 15–25% per priced round, but it varies widely by market, stage and terms. Use this tool to compare offers rather than benchmarks.
Why does the option pool shuffle matter?
Two term sheets with the same headline pre-money can give founders very different ownership depending on pool size and where it is counted. Compare the effective pre-money.
Disclaimer: These calculators are simplified educational models, not legal, tax, investment or financial advice. Real outcomes depend on the exact wording of your charter, SAFE, side letters and shareholder agreements (e.g. rounding, dividends, anti-dilution, carve-outs, escrow, fees). Always verify with a qualified lawyer or advisor before relying on any figure. No data you enter leaves your browser.