Free founder ownership tool
Startup Equity Dilution Calculator
See how founder ownership changes after multiple priced investment rounds and how option-pool expansion can add dilution before new investors come in.
Simple dilution model
4 financing roundsTrack founder ownership through priced rounds
Starting ownership
Investment rounds
RoundPre-money valuationNew investment
Round 1
$
$
Round 2
$
$
Round 3
$
$
Round 4
$
$
Simple methodFor each priced round, new investor ownership = investment ÷ (pre-money valuation + investment). Existing holders retain the remainder. Founder ownership after the round = prior founder ownership × pre-money valuation ÷ post-money valuation. A round with zero investment is skipped.
Advanced dilution model
4 priced roundsModel actual shares and pre-money option-pool top-ups
Starting fully diluted cap table
Priced rounds & option-pool targets
RoundPre-money valuationInvestmentTarget option pool after round
Seed
$
$
%
Series A
$
$
%
Series B
$
$
%
Series C
$
$
%
Advanced option-pool methodEach target pool percentage is treated as a post-financing fully diluted target, with any required new pool shares created immediately before the round. That means the pool top-up dilutes existing holders before the new investor shares are issued. If the existing pool already meets the target, no additional pool shares are created.
Round-by-round dilution
Share-based modelFounder ownership through each financing stage
| Stage | Pre-money | Investment | Pool top-up shares | Price / share | Round investor % | Founder % after round | Total FD shares |
|---|
Final cap table
Fully diluted ownershipOwnership after all active rounds
| Holder / category | Final shares | Final ownership | Value at latest post-money |
|---|
Valuation sensitivity
Investments and pool targets unchangedFounder ownership if every round valuation changes
| Pre-money valuation scale | Founder ownership | Founder retained | New investors combined | Option pool | Founder stake value |
|---|
Investment sensitivity
Valuations and pool targets unchangedFounder ownership if round sizes change
| Investment scale | Total capital raised | Founder ownership | Founder retained | New investors combined | Final FD shares |
|---|
Option-pool sensitivity
All round pool targets scaled togetherFounder ownership as pool targets change
| Pool-target scale | Founder ownership | Total pool shares added | Final option pool | New investors combined |
|---|
Scope
Cap-table math is not a substitute for transaction documents
This calculator models common-stock dilution from priced equity rounds and pre-money option-pool expansion. It does not model SAFEs, convertible notes, liquidation preferences, warrants, anti-dilution provisions, secondary sales, participating preferred, taxes, vesting or legal rights. Actual financing documents and capitalization records control ownership.