Startup dilution calculator
Every priced round and option pool dilutes your ownership. This calculator shows what happens to your stake round by round: enter your starting ownership, then add each round's new-money percentage and any option-pool top-up, and see your fully diluted position at the end. No sign-up, no spreadsheet. The math is the standard post-money dilution every founder should understand before they negotiate a term sheet.
| Round | Dilution | Your ownership after |
|---|---|---|
| Seed | -28.0% | 72.0% |
| Series A | -25.0% | 54.0% |
Simplified model: each round dilutes existing holders by the new investor stake plus any option-pool increase. Real rounds can differ with SAFEs, pro-rata and participation.
How it works
- 1Set your current ownership and the rounds you expect to raise.
- 2For each round, enter how much new equity investors take, plus any option-pool increase.
- 3The tool compounds the dilution and shows your ending ownership and a round-by-round table.
Frequently asked questions
How is founder dilution calculated?+
Each round multiplies your ownership by the percentage that remains after new investors and any option pool take their share. Raising 20% means you keep 80% of whatever you held going in, so dilution compounds across rounds.
Does the option pool dilute founders?+
Yes. A pre-money option pool top-up dilutes existing shareholders, including founders, before the new investor's money goes in, so it is effectively part of your round dilution. This tool lets you add a pool increase per round.
What ownership should a founder expect after a few rounds?+
It varies widely, but founders commonly hold somewhere in the range of a third to half of the company after a seed and a Series A, depending on how much they raise and how large the option pools are. Use the tool with your real numbers rather than a rule of thumb.
Is this the same as a SAFE conversion?+
Not quite. SAFEs and convertible notes convert into equity at a later priced round and can change the dilution math. Use the SAFE calculator for that, then bring the resulting ownership into your dilution model.
Raising now? Share your data room securely with Plox
Plox is the secure way to share, track and run deals on the documents these tools help you create. Free to start.