Equity Dilution Calculator
Calculate how new share issuance dilutes existing ownership.
This Equity Dilution Calculator helps you understand exactly how much your ownership will shrink when new shares enter the picture. You provide your current ownership percentage, the total number of existing shares, and the number of new shares being issued. The tool computes your new ownership percentage and the absolute dilution you experience.
Dilution is not inherently bad. If a funding round values the company higher than its previous valuation, your smaller percentage may be worth more in dollar terms than your larger percentage was before. This is sometimes called accretive dilution, where you own less of a more valuable company. The concern arises when dilution outpaces valuation growth, leaving shareholders with both a smaller percentage and less economic value.
Founders commonly face dilution from multiple sources across a company's life: seed rounds, Series A through D, option pool expansions, convertible note conversions, and warrant exercises. Each event chips away at founder ownership, and the cumulative effect can be dramatic. A founder who starts with 50 percent may hold single-digit ownership by a late-stage round if they are not careful about managing dilution at each step.
Use this calculator to model upcoming rounds and understand the trade-offs before signing a term sheet. Knowing your dilution number empowers you to negotiate from a position of clarity.
Calculator
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How to Use
- Enter your current ownership percentage in the company
- Enter the number of new shares being issued in this round or event
- Enter the current total number of shares outstanding
- Click Calculate to see your diluted ownership and percentage points lost
- Compare scenarios by adjusting the new shares issued to find an acceptable dilution level
FAQ
Is dilution always bad for existing shareholders?
Not necessarily. Dilution reduces your ownership percentage, but if the new investment increases the company's valuation by more than the dilution percentage, your shares are worth more in absolute dollar terms. For example, owning 20 percent of a $50 million company is worth more than owning 25 percent of a $30 million company. The key is whether dilution is accompanied by proportional or greater value creation.
How can founders protect themselves from excessive dilution?
Founders can negotiate anti-dilution provisions, maintain pro-rata rights to participate in future rounds, keep option pools sized appropriately rather than oversized, and raise capital only when the valuation justifies the dilution. Building a profitable business that does not require frequent fundraising is the most effective protection against dilution.
What is the difference between dilution from fundraising and dilution from option pools?
Fundraising dilution occurs when new shares are sold to investors in exchange for capital, bringing money into the company. Option pool dilution occurs when shares are reserved or granted to employees, advisors, or consultants, typically without immediate cash entering the company. Both reduce existing shareholder percentages, but fundraising dilution is accompanied by new capital while option pool dilution is a cost of attracting talent.
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