Equity Dilution Calculator
Follows a stake through up to three funding rounds and an option pool top-up.
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
The formula
each round: stake × (1 − equity sold) pool before the round: stake × (1 − equity sold − pool target) ÷ (1 − pool now) pool after the round: stake × (1 − equity sold) × (1 − pool target) ÷ (1 − pool now × (1 − equity sold))
With no pool to start from, the two pool lines reduce to 1 − equity sold − target, and (1 − equity sold) × (1 − target). The pool target is measured after the round in both cases.
What to watch out for
All percentages are of the fully diluted company. Each round is assumed to issue only new shares, and this holder buys none of them. The top-up raises the unallocated pool to the target once that round closes, and nothing is added if the pool is already there. No options are assumed to be granted from the pool between rounds. SAFEs, convertible notes and liquidation preferences are not modelled.
Frequently Asked Questions
Does it matter whether the option pool comes before or after the round?
Yes. A 50% holder in a round selling 20% with a new 10% pool ends at 35.00% if the pool comes first, with the investor keeping 20.00%. If it comes after, the holder ends at 36.00% and the investor at 18.00%.
How does dilution add up over several rounds?
Each round multiplies, so the percentages do not simply add. A founder with 100% selling 20%, 25%, 20% in turn ends with 48.00%.
Does a smaller stake mean less money?
Not necessarily. A smaller share of a company whose value has risen can be worth more, though preferences and later terms can change what common shares receive.