Stock Split Calculator
See shares, price, and cost basis after a split
Enter the shares you own, the price before the split, and the ratio. A 4-for-1 forward split and a 1-for-10 reverse split use the same form.
After the split
Breakdown
What the calculator counted
Next check
A split changes the share count. It does not tell you whether the trend is still advancing.
How to use it
Step 1
Enter the position and the ratio
Add the shares you hold and the price before the split. Then enter the ratio as new shares for old shares. Add cost basis only if you want the adjusted basis per share.
- 4-for-1 means 4 new shares for every 1 old share
- 1-for-10 is the reverse stock split case
Step 2
Read the new share count and price
The result shows exact shares, the adjusted price, and the same position value. If the ratio leaves a fraction, it also shows whole shares and cash in lieu.
- Total cost basis does not change
- Per-share cost basis moves with the price
How a stock split calculator works
New shares equal old shares times (new shares in the ratio divided by old shares in the ratio). New price equals old price times the inverse of that ratio. A 3-for-2 split multiplies shares by 1.5 and multiplies the price by 2/3.
Position value is shares times price, and it is the same before and after. If you enter a cost basis, the per-share basis is adjusted the same way as the price. Total basis stays put.
A split does not tell you whether to hold. Check Stage Analysis if you want the stock’s trend stage after the share count changes.
Results are calculated from the numbers you enter, not generated by AI and not pulled from a brokerage account. This tool is not investment or tax advice.
Frequently asked questions
How does a stock split calculator work?
A split is written as new shares for old shares. Multiply your shares by that ratio and divide the price by the same ratio. A 4-for-1 split turns 100 shares at $200 into 400 shares at $50. The position value stays the same.
What is a reverse stock split calculator?
It uses the same math. A 1-for-10 reverse split means you receive 1 new share for every 10 old shares, and the price is multiplied by 10. Enter 1 in new shares and 10 in old shares.
Does a split change what my shares are worth?
No. Share count and price move in opposite directions, so the market value of the position is unchanged at the moment of the split. Later trading can move the price.
What happens to fractional shares?
Some brokers keep the fraction. Others pay cash for it, called cash in lieu. This calculator shows the exact share count, the whole shares, and the cash for the leftover fraction at the post-split price.
Does a split change my cost basis?
Total cost stays the same. Cost basis per share is adjusted by the split ratio, the same way the market price is. Cash paid for a fractional share can be treated as a small sale. This tool is not tax advice.
Is this investment advice?
No. The tool is for educational and informational use and does not recommend buying or selling a security.
Example splits
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