Dilution Calculator
Dilution measures how your ownership % shrinks as the company issues new shares in funding rounds. This calculator lets you add successive rounds with raise, pre-money, and option-pool top-up, and shows your ownership and implied value at each stage.
How to use this calculator
- Set your starting ownership: Enter your ownership % before the first modeled round.
- Add rounds: For each round, enter name, raise amount, pre-money valuation, and any option-pool top-up.
- Pick pool timing: Toggle whether the option-pool top-up is pre-money (dilutes existing holders) or post-money (dilutes new investor too).
- Review the chart: See ownership % and implied value at each round, plus final ownership at exit.
Assumptions
| Assumption | Value |
|---|---|
| Rounds | Priced rounds only (no SAFEs / notes conversion) |
| Option pool timing | Pre- or post-money per round |
| Anti-dilution | Not modeled (weighted-average or full ratchet) |
| Exit value | Implied by last round's post-money |
Frequently asked questions
What is dilution?
Dilution is the reduction in your ownership percentage when the company issues new shares — typically in a funding round or to increase the option pool.
How is pre-money vs post-money different?
Pre-money is the valuation before the new investment; post-money = pre-money + amount raised. Your dilution equals amount-raised / post-money.
Why does the option pool matter?
New investors usually require the pool to be topped up before their money goes in. When the top-up is 'pre-money', it dilutes existing holders only; 'post-money' spreads dilution to the new investor too.
Does this model SAFEs or convertible notes?
No — priced rounds only. SAFEs typically convert at the next priced round using a cap and/or discount and can be modeled by adding an equivalent priced round.
How is implied value calculated?
Implied value at each round = your ownership % × the round's post-money valuation. It's a paper number until liquidity.
What's a typical founder ownership at Series C?
Highly variable, but a solo founder typically ends up in the 5–15% range by Series C after seed + Series A + B + C rounds, before secondary sales.
How can I reduce dilution?
Raise less, at higher valuations, with smaller pool top-ups. Bootstrap longer before the first priced round. Structure secondaries and grants thoughtfully.
Does anti-dilution protection change this?
Yes for existing preferred holders on down rounds, but it's not modeled here. Common shareholders (founders, employees) don't get anti-dilution — that's why down rounds hurt them most.
Is this tax advice?
No. Dilution modeling is illustrative for planning and is not tax, legal, or investment advice.