Tools · Equity dilution calculator
See exactly what a round costs you
Enter your cap table and the round terms. Get price per share, ownership before and after for every holder, and a side-by-side of the option pool shuffle. Runs entirely in your browser — we do not log your inputs.
The round
Post-money is $25,000,000.
Cap table before the round
Enter fully diluted shares — granted options belong on a holder line, not in the unallocated pool.
Round outcome
- Price per share
- $1.9231
- New investor
- 20.00%
- Existing holders
- 70.00%
- Fully diluted shares
- 13,000,000
Pre-money $20,000,000
2,600,000 shares
was 91.00%
was 10,000,000
Post-money valuation $25,000,000. The round creates 400,000 new option pool shares, taking the unallocated pool to 1,300,000 (10.00% of the post-round cap table).
Ownership before and after
| Holder | Shares before | % before | Shares after | % after | Dilution |
|---|---|---|---|---|---|
| Founder 1 | 4,000,000 | 40.00% | 4,000,000 | 30.77% | −9.23 pp |
| Founder 2 | 3,000,000 | 30.00% | 3,000,000 | 23.08% | −6.92 pp |
| Seed investors | 1,500,000 | 15.00% | 1,500,000 | 11.54% | −3.46 pp |
| Granted employee options | 600,000 | 6.00% | 600,000 | 4.62% | −1.38 pp |
| Unallocated option pool | 900,000 | 9.00% | 1,300,000 | 10.00% | +1.00 pp |
| New investor | 0 | 0.00% | 2,600,000 | 20.00% | — |
Existing holders keep the same number of shares. Their percentage falls because the denominator grew — that is all dilution is.
The option pool shuffle
Identical headline terms. The only change is whether the new 10% option pool is carved out of the pre-money valuation or added after the round prices.
| Outcome | Pool pre-money | Pool post-money | Difference |
|---|---|---|---|
| Existing holders keep | 70.00% | 70.60% | +0.60 pp |
| New investor gets | 20.00% | 19.40% | −0.60 pp |
| Price per share | $1.9231 | $2.00 | — |
| New pool shares created | 400,000 | 388,889 | — |
A pre-money pool lowers the price per share, so existing holders pay for the whole pool and the new investor still lands on exactly 20.00%. Push the pool post-money and the investor shares the cost.
How this is calculated
- Convert the valuation to a pre-money and a post-money figure
post-money = pre-money + amount raised - Fix the investor’s ownership from the money, not the shares
investor % = amount raised ÷ post-moneyThis holds regardless of share counts, which is why a round is quoted in dollars. - Pre-money pool: solve for the post-round share count
shares after = existing allocated shares ÷ (1 − pool % − investor %)The pool sits inside the pre-money, so every new pool share comes out of existing holders. - Post-money pool: price first, then add the pool
price = pre-money ÷ shares before · new pool = (pool % × shares after round − existing pool) ÷ (1 − pool %)The investor is diluted by the pool alongside everyone else. - Recompute every percentage against the new total
holder % = holder shares ÷ shares after
Share counts are rounded to whole shares, so a percentage can land a hair off a round number. For the SAFEs and notes converting in the same round, use the SAFE conversion calculator.
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What this calculator does
Dilution is not a haircut on your shares. You keep every share you owned before the round — what changes is the denominator. Issue new shares to an investor and to an expanded option pool, and your fixed share count becomes a smaller slice of a bigger company. The table above shows both halves of that: share counts stay flat for existing holders while percentages fall.
The new investor’s percentage is set by money, not by shares: amount raised divided by the post-money valuation. A $5m round on a $20m pre-money is 20% of the company, whatever the share count. Everything else — price per share, how many shares get issued — is downstream of that and of how many shares already exist.
The one thing people get wrong: the option pool shuffle
A term sheet will usually ask for a new option pool sized as a percentage of the post-round company, created before the round closes. That single word does a lot of work. A pre-money pool sits inside the pre-money valuation, so it expands the share count the round prices against. The investor still lands on their agreed percentage, which means every share of the new pool is paid for by the existing holders — and the real price per share you received is lower than the headline pre-money implies.
Move the same pool post-money and the investor is diluted by it alongside everyone else. In the seeded example above, that single change is worth roughly six tenths of a percentage point to the existing holders. On a larger pool, or a larger round, it is worth a great deal more. Neither treatment is dishonest; the pre-money pool is market standard. But it is a negotiable term, and it is worth negotiating with the number in front of you.
The second common error is arguing about the pool percentage rather than the hiring plan behind it. A pool is sized to cover the grants you expect to make before the next round. If you can show the plan, you can usually argue the pool down — and an unused pool is not wasted, it simply carries forward.
How to read the output
Price per share is the pre-money valuation divided by the pre-money share count — including the new pool if the pool is pre-money. It is the cleanest single number for comparing two term sheets, because it already absorbs every pool and share-count assumption.
Dilution in the final column is expressed in percentage points, not as a percentage of a percentage. A founder going from 40% to 30.77% has been diluted by 9.23 points, or 23% of what they held. Both framings are used in practice; points are less ambiguous.
This model assumes a single priced round with no converting SAFEs or notes. If you have SAFEs outstanding, they convert in the same round and take their shares out of the pre-money too — model that in the SAFE conversion calculator first, then bring the resulting cap table back here. Nothing on this page is legal, tax, or investment advice.