How to use the stock split calculator
- Enter the number of shares you own and the price per share before the split.
- Enter the ratio as new shares for every old shares. A 2-for-1 split is 2 and 1. A 1-for-10 reverse split is 1 and 10.
- If you want the cost per share, open More options and enter your total cost basis.
- Read the new share count, the new price and what happens to any fractional share.
Formula
New shares = old shares x new / old
New price = old price x old / new
Value after = new shares x new price = value before
The ratio is reduced to lowest terms, so 6-for-4 is shown as 3-for-2. Whole shares are counted exactly and any remainder is reported as a fractional share.
A 2-for-1 split and a 1-for-10 reverse split
Own 100 shares at $150, worth $15,000. A 2-for-1 split gives you 200 shares at $75, still worth $15,000. A cost basis of $12,000 becomes $60 a share across the 200 new shares.
Now own 95 shares at $2 and the company does a 1-for-10 reverse split. You hold 95 / 10 = 9.5 shares at $20. That is 9 whole shares plus half a share, worth $10. A 3-for-2 split on 101 shares at $150 gives 151.5 shares at $100.
Forward and reverse splits
A forward split gives you more shares at a lower price, which makes each share cheaper to buy without changing what the company is worth. A reverse split does the opposite: fewer shares at a higher price. In both cases the total value of your holding does not change at the moment of the split. Prices then move on their own, so the market price after a split is not exactly the price this page shows.
Fractional shares and taxes
How a fractional share is handled depends on the company and your broker. Some pay cash for it and some keep fractions on your account, so read the notice from your broker. The way your cost basis is adjusted and whether a split is taxed follow the rules where you live, and this page does not apply them.
To track your gain or loss use the Stock Profit Calculator, to average several purchases use the Stock Average Calculator and to estimate tax on a sale try the Capital Gains Calculator.
Assumptions and limits
- The split is announced as new shares for old shares and happens in one step.
- The price shown is the price adjusted by the ratio, not a forecast of the market price.
- Cash paid for fractional shares is not modeled beyond the value of the fraction.
- Nothing is uploaded. Calculations run in your browser.
Frequently asked questions
Does a split make my investment worth more?
No. You own more shares at a lower price, or fewer at a higher one, and the total value stays the same at the moment of the split. Later price changes are separate.
How do I enter a reverse split?
Put the smaller number first. A 1-for-10 reverse split is 1 new share for every 10 old shares, so enter 1 and 10. The page labels the result as a reverse split.
What happens to a fractional share?
That is up to the company and your broker. Some pay cash for the fraction and some credit fractional shares. The page shows the whole shares, the fraction and its value at the new price.
How is my cost basis affected?
The total cost basis stays the same and is spread across the new number of shares, so the cost per share changes by the ratio. Check your local tax rules for details.