TL;DR
Startup dilution is the reduction in an existing holder's ownership percentage when the company issues new shares or share-equivalent rights. Dilution can come from priced equity, SAFE conversion, note conversion, option pool increases, warrants, and other financing terms.
Common sources of dilution
| Source | How it dilutes founders | What to model |
|---|---|---|
| Priced Round | New shares are issued to Investors. | Pre-money valuation, investment amount, and post-money ownership. |
| SAFE conversion | Future shares are issued based on cap, discount, or other formula. | Every SAFE converting under each valuation scenario. |
| Convertible note | Principal plus interest may convert into shares. | Accrued interest and qualified financing mechanics. |
| Option pool | Shares reserved for hiring reduce ownership percentages. | Whether the pool is increased before or after the Investor price. |
| Pro rata rights | Existing Investors may buy more to maintain ownership. | Allocation in the next Round and founder ownership after participation. |
| MFN clauses | Later better terms can spread to earlier Investors. | Worst-case if all eligible Investors adopt the better term. |
Also Read: Pre-money vs post-money SAFE
Founder dilution checklist
- Start with the fully diluted current cap table.
- Add every outstanding SAFE, note, warrant, and side letter.
- Model low, base, and high next-Round valuations.
- Show option pool changes separately from new Investor ownership.
- Keep assumptions tied to source documents in the Data Room.
Bottom line
Founders do not lose ownership because a term is called a SAFE, note, cap, or discount. They lose ownership because the conversion math issues shares. The founder who can explain that math has more control in negotiation.