This calculator estimates how much of a pre-seed company remains with founders and other existing holders after a new financing. It starts with the current ownership split and applies the post-money percentage issued to new investors.
The output is useful for cap-table planning and for comparing round structures before detailed share counts are available. It assumes all existing holders dilute proportionally and that the entered groups account for the current cap table. Option-pool refreshes, SAFEs, notes, and pro rata purchases should be modeled separately when relevant.
1. Enter the current cap-table split
Provide founder, employee/option, and other existing ownership percentages that total 100%.
2. Enter new investor ownership
Use the percentage of the company the new investors will own after closing.
3. Review each group
Existing groups are scaled down proportionally by the portion allocated to investors.
4. Reconcile with transaction documents
Use the result as a percentage model before converting terms into exact shares.
Existing group ownership after = Existing group ownership before × (1 − New investor ownership)
The founders, employee/options, and other groups must total 100% before the round. The model assumes proportional dilution for all existing groups.
The main result is the founders’ combined post-money ownership after the modeled investor issuance.
A pre-money option-pool increase can shift dilution disproportionately toward existing holders.
Given: Founders 80%, employees/options 10%, other holders 10%, and new investors receive 18% post-money.
Calculation: Existing holders retain 82% of their prior stakes. Founders = 80% × 0.82 = 65.6%; employees = 8.2%; others = 8.2%.
Result: Founders own 65.6% after financing and investors own 18%.
The calculator allocates the complete pre-round cap table across the entered groups before applying new dilution.
Use the same fully diluted convention applied in your cap table, which may include granted and reserved options.
This model assumes they do not. Additional purchases would require a more detailed transaction calculation.
They should be converted into an ownership effect first, then included in the relevant existing or new holder group.
This page shows the post-round split across several holder groups; the dilution calculator focuses on one holder’s percentage change.