Calculate how your stock ownership percentage will be affected by new share issuances, investment rounds, and employee option pools. Understand the real impact of dilution on your equity value.
You own 10,000 shares in a startup with 1,000,000 total shares outstanding. Your current ownership is 1% (10,000 ÷ 1,000,000).
The company issues 200,000 new shares to a new investor to raise capital. After the issuance, total shares outstanding become 1,200,000.
Your new ownership percentage: 10,000 ÷ 1,200,000 = 0.83%
Dilution impact: Your ownership dropped from 1% to 0.83%, a 16.7% relative dilution. If the company's valuation grew proportionally, your economic value may still have increased, but your control and voting power decreased.
Understanding how different types of dilution affect your ownership is crucial for equity planning. Below is a comparison of the three common dilution scenarios handled by this calculator.
| Scenario | What Happens | Who Is Affected | Typical Trigger |
|---|---|---|---|
| Simple Dilution | New shares issued, total outstanding increases | All existing shareholders | Secondary offerings, stock splits |
| Investment Round | Investor buys new shares at a set price | Founders, early employees, angel investors | Series A, B, C funding rounds |
| ESOP Pool | Options granted to employees from pool | Existing shareholders (pool expansion) | New hires, employee retention grants |
Enter the number of shares you own, the total shares outstanding before the new issuance, and the number of new shares being issued. The calculator will show your old ownership percentage, new ownership percentage, and the dilution impact.
Enter the pre-money valuation, investment amount, price per share, existing employee option pool percentage, and your current ownership percentage. The calculator determines post-money valuation, new shares issued, and your diluted ownership after the round.
Enter your current shares outstanding, option pool size percentage, number of new hires, average options per hire, and your current shares. See how option grants to new employees dilute your ownership and what remains in the pool.
Your Shares = Number of shares you hold
Total Outstanding = All issued shares (including new ones)
New Ownership = Ownership percentage after dilution
Old Ownership = Ownership percentage before dilution
Pre-Money = Valuation before investment round
Investment Amount = Capital raised in the round
Ownership % = Your percentage after dilution
Post-Money Valuation = Company value after the round
Our stock dilution calculator is designed for startup founders, early employees, investors, and anyone holding equity who wants to understand how new share issuances will affect their ownership. Whether you're planning a funding round, setting up an employee option pool, or simply trying to understand your cap table, this tool provides clear, actionable insights.
Disclaimer: This stock dilution calculator is for educational and planning purposes only. Actual dilution depends on the specific terms of investment agreements, option plans, and corporate actions. Always consult with qualified legal and financial professionals for personalized equity planning advice.