Founder Dilution Calculator: Investor Stake and Remaining Ownership
Work out what a funding round leaves of a founder's ownership — the investor stake on one side, the diluted share of everyone else on the other.
Adjust the inputs and select Calculate for a full breakdown.
Compare Common Scenarios
How the numbers shift across typical situations for this calculator:
| Scenario | Investor stake | Remaining ownership |
|---|---|---|
| 2M new · 10M total | 20.00% | 80.00% |
| 500k new · 5M total | 10.00% | 90.00% |
| 750k new · 3M total | 25.00% | 75.00% |
| 1.25M new · 25M total | 5.00% | 95.00% |
How This Calculator Works
Enter the new shares issued to the investor and the total outstanding shares after the round closes. The calculator divides one by the other and multiplies by 100 to give the investor's stake, with the remaining ownership — typically founders and prior shareholders — shown alongside.
The Formula
Part as a Percentage of a Whole
Part is the portion, Whole is the total it belongs to
Worked Example
An investor receiving 2,000,000 new shares against a 10,000,000-share post-money cap table takes a 20% stake. The remaining 80% sits with everyone who held shares before the round, diluted proportionally to their pre-round ownership.
Key Insight
Dilution is not just the round itself — the option pool expansion that almost always accompanies a priced round dilutes existing shareholders before the investor even arrives. A 'clean' 20% round can quietly cost founders another 5% to 10% via a pool top-up funded entirely from the pre-money cap table. Read the term sheet, not just the headline percentage.
Frequently Asked Questions
How is investor stake calculated?
Divide the new shares issued to the investor by the total post-money share count and multiply by 100. Two million new shares against a 10 million post-money table is a 20% stake.
What is post-money vs pre-money?
Pre-money is the cap table before the round. Post-money adds the new investor shares. Dilution math always uses post-money for the percentage stake.
What about the option pool?
Most priced rounds require the option pool to be topped up from the pre-money cap table. That dilutes founders before the investor even arrives, so the real founder dilution is usually larger than the headline round percentage.
How do anti-dilution clauses change this?
Anti-dilution provisions (full-ratchet or weighted-average) protect prior investors from dilution if a future round is priced below theirs. Founders rarely have them and bear the full dilution in those cases.
Is more dilution always bad?
No. Taking a 25% dilution on a $20M round that grows the company tenfold is far better than refusing the round and stagnating with 100%. The right question is what the dilution buys, not the dilution percentage by itself.
Related Calculators
Methodology & Review
The investor stake is new shares issued divided by total post-money shares, multiplied by 100. The complement is the surviving share of the existing cap table — typically founders and prior shareholders, diluted proportionally by the round. Anti-dilution provisions and option pool expansions are not separated out.
Written by Ugo Candido · Last updated May 17, 2026.