Calculators·Share counts from SEC filings
Dilution calculator
When a company sells new shares, the pizza gets cut into more slices. You still have the same number of shares, but each one is a smaller piece of the company. This shows how much smaller, and what the sale does to the value of each share.
Your slice of the company shrinks by
0%
How the math works
Your ownership is your shares divided by every share that exists. New shares go in the bottom of that fraction, so your slice gets smaller even though you didn't sell anything. Saying you own "1 in every 100,000 shares" is the same number, just easier to picture.
Dilution is the new shares divided by the total after they're issued, and that's exactly how much your slice shrinks. It's a little smaller than how much the share count grew: 10 million new shares on top of 100 million is 10% more shares, but they're 9.1% of the new total, so your slice shrinks by 9.1%.
Add both prices and it also shows what happens to each share. Before the sale, the company is worth the share count times today's price. The sale adds the cash it raises. Divide that by the new share count, and you get the value per share after. If the new shares sell below today's price, each share is worth a little less on paper. If they sell at or above today's price, it isn't.
Dilution isn't automatically bad. If the company turns that cash into a business that's worth a lot more, a smaller slice of a bigger pizza can be worth more than the slice you had. The real question is what they do with the money. More on that in the glossary: dilution.
What this leaves out
Shares that could exist later. Stock options, warrants, restricted stock units and convertible notes can all turn into shares down the road. Counting them too gives you the "fully diluted" share count, which is bigger than the shares outstanding today. If you want them in the math, add them to the new shares.
How the shares get sold. Some companies use an at-the-market program, or ATM, which basically just means selling new shares into the market a little at a time, at whatever the price is that day. There's no single offering price with an ATM, so put in the average price you expect.
It also leaves out the fees the company pays the bankers (so the cash it actually keeps is a bit lower), shares the company buys back, and however the stock price reacts to the news. Real prices don't follow the on-paper math.
Watch
Sources: share counts and the past year's change come from each company's own filings on SEC EDGAR (the cover of the latest 10-Q or 10-K). The definition of an at-the-market offering is from SEC Rule 415(a)(4). The ownership and per-share math is plain arithmetic, shown above. Last checked against these sources on Nov 9, 2026.
An estimate for learning, not advice. I'm a CPA, but I'm not your CPA. This site doesn't keep stock prices, so the prices here are only what you type. Nothing you type leaves your browser. Full disclaimer.