Free tool
Co-founder equity split calculator
Enter what each founder is actually putting in — unpaid time, forgone salary, cash, role and expertise — and see the same team modelled three ways: an equal split, a dynamic contribution-based split, and a role-weighted split.
Nothing is saved or sent anywhere. The point is not to find one number; it is to see how far apart three defensible frameworks put you before you write anything into a founders' agreement.
Your founding team
Three ways to split the same company
| Founder | Equal | Dynamic | Role-based |
|---|---|---|---|
| Founder A | 50.0% | 50.0% | 50.0% |
| Founder B | 50.0% | 50.0% | 50.0% |
What this is telling you
Your contribution-based split lands within 0.0% of an equal split. An equal split is defensible here — but still write a vesting schedule and a tie-break rule into the agreement.
How each framework is calculated
- Equal
- 100% divided by the number of founders. Fast, signals parity, ignores contribution.
- Dynamic (Slicing Pie style)
- Unpaid time is valued at the founder's forgone monthly salary, multiplied by their full-time percentage and months committed, then doubled to price the risk of unpaid work. Cash is counted at 4x, because cash is gone the moment it is spent. The totals are normalised into percentages.
- Role-based
- Role responsibility is double-weighted against domain expertise, with a floor so no founder is zeroed out on a subjective slider. Useful when contributions are hard to price in hours.
These are planning models, not legal or financial advice. Have a lawyer paper the final split.
The number is the easy part
The percentage is only one part of the decision. Expectations about exit timelines, decision authority, workload, and changing capacity also matter. FounderSync gives both founders the same twenty questions independently, then identifies stated alignment and differences worth discussing.
Equity split questions founders ask
How should co-founders split equity?
There is no single correct answer. Most teams choose between an equal split, a dynamic split that tracks actual contribution over time (Slicing Pie), and a role-based split weighted by responsibility and expertise. This calculator shows all three side by side from the same inputs so you can see how far apart they are before you commit.
Is a 50/50 equity split a bad idea?
Not inherently. A 50/50 split signals parity and is fast to agree on. It becomes a problem when contributions diverge sharply and there is no vesting schedule or tie-break rule for deadlocked decisions. If the equal and dynamic results in this calculator differ by more than about ten points, treat that gap as a conversation you owe each other.
How does the dynamic (Slicing Pie) calculation work here?
Each founder earns notional slices for unpaid time (full-time percentage multiplied by months, weighted for forgone salary risk) and for cash invested, with cash weighted more heavily than time because cash is non-recoverable. Slices are then normalised into percentages. It is a simplified model of Mike Moyer's Slicing Pie framework, not a substitute for it.
Should equity be vested?
Almost always. A standard four-year vest with a one-year cliff protects the team if a founder leaves early, regardless of which split framework you pick. Whatever number you land on, write the vesting schedule into the founders' agreement at the same time.
Does this calculator store my numbers?
No. Everything runs in your browser. Nothing is submitted, saved, or sent to a server.