Ownership Percentage and Dilution: Reading a Cap Table
Ownership percentage is your shares divided by total shares outstanding. When a company issues new shares, your count does not change — the denominator grows, and your slice gets smaller. That is dilution, and it is arithmetic, not a penalty.
Calculating your stake
- Ownership % = your shares ÷ total shares outstanding × 100.
- After a round: your shares ÷ (existing + newly issued) × 100.
- Value of the stake = ownership % × post-money valuation.
- 150,000 of 1,000,000 shares is 15%, falling to 12% after 250,000 new shares.
Issued versus fully diluted
Fully diluted counts everything that could become a share: the option pool, warrants, SAFEs and convertible notes. It is always the lower ownership figure and the honest one. Anyone quoting an issued-only percentage in a negotiation is describing a version of the company that will not exist on the day it matters.
Where dilution bites hardest
- Pre-money option pools: existing holders absorb the whole top-up before the investor's money lands.
- Convertible notes and SAFEs converting at a discount issue more shares than the headline implies.
- Down rounds with anti-dilution protection reprice earlier shares at the founders' expense.
- Being diluted at a higher valuation is usually fine — a smaller slice of a much larger pie.
Key takeaways — Ownership Percentage Calculator
- Ownership % = your shares ÷ total shares outstanding.
- Always negotiate on fully diluted figures.
- Dilution matters less than the valuation it buys — track value, not just percentage.