What is Founder Dilution?
Founder dilution is the drop in founders’ ownership percentage when new equity is issued in a financing round — and it can also happen when the employee option pool is created or expanded.
It matters because ownership drives real outcomes: governance leverage (control and voting power), incentive alignment (retention and hiring), and the founders’ share of eventual exit value. If you want to see the “before vs after” impact of a round, start with a cap table view and sanity-check the core math with an ownership percentage calculation on a fully diluted basis.
In practice, dilution is tightly connected to option pool sizing (use the ESOP calculator to model pool % and grants), round pricing (run pre-money valuation to understand what you’re actually selling), and convertibles like SAFE or notes that convert later and can shift dilution at the next priced round. To translate dilution into “what do I actually take home?”, pair this with an exit proceeds (or exit waterfall) calculator to model payouts under different exit values and preferences.
Formula
Example
Inputs (priced round, no option pool increase, no SAFEs/notes converting, no secondary):
- Pre-money valuation: $20,000,000
- New investment amount: $5,000,000
- Founders’ combined pre-round ownership: 55%
Steps:
1) Post-money valuation:
2) New investors’ ownership:
3) Pre-round holders keep:
4) Founders’ post-round ownership:
5) Other pre-round holders (post-round):
6) Founder dilution (percentage points):