Share Dilution from Options Calculator
Measure how exercising employee stock options dilutes existing shareholders — the new share count, dilution percentage and your shrunken ownership stake.
How it works
New total shares = existing + option shares · Dilution % = option shares ÷ new total × 100 · Your stake = your shares ÷ new total × 100
When employees or investors exercise options, the company issues brand-new shares, so the total count grows and every existing holder owns a smaller slice of the same company. Dilution is measured against the post-issuance total, not the original count. It also spreads earnings and dividends across more shares, which is why fully diluted share counts appear alongside basic counts in filings.
Worked example
A company with 10,000,000 shares issues 1,000,000 from options, taking the total to 11,000,000. Dilution is 1,000,000 ÷ 11,000,000 = 9.09%. A 100,000-share holder’s stake slips from 1.0000% to 0.9091%.
Frequently asked questions
Why is dilution measured against the new total?
Ownership is your shares divided by all shares outstanding after the new ones are issued. Because the denominator grows, the correct dilution base is the post-issuance total, which is why 1M new shares on 10M dilute by 9.09%, not 10%.
Does dilution always hurt shareholders?
Not necessarily. If the options helped attract talent or raise capital that grows the business faster than the share count, the larger, more valuable company can leave each holder better off despite the smaller percentage stake.
What is fully diluted share count?
It is the total shares that would exist if every option, warrant and convertible security were exercised. It is the conservative denominator for per-share metrics because it captures potential dilution already committed.
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Educational estimate, not investment advice. Trading forex, futures and options carries substantial risk of loss.