Stock Split Calculator
New share count, adjusted price, and unchanged value from any split ratio.
What it does
A stock split reslices the same company pie: more shares at a lower price, or fewer at a higher one in a reverse split. The ratio moves both sides at once, leaving total value untouched on the effective date.
The tool above takes shares owned with price and the split ratio. It returns the new share count with the adjusted price and the before equals after value beside them.
The default of 10 shares at $100 in a 2-for-1 gives 20.0000 shares at $50.00, value $1,000.00 both ways. A 1-for-200 reverse split turns 5,000 shares at $0.10 into 25.0000 at $20.00, still $500.00.
The mechanics follow FINRA split and corporate action guidance with matching worked examples. Both stress that value and ownership share hold still while the market may move after.
How to use
- Enter shares owned before the split.
- Enter the pre split price per share.
- Enter the ratio as new-for-old, like 2 and 1.
- Read new shares first, then the adjusted price.
- Check the value line: both sides must match.
Formula
- A
- New shares per batch in the ratio.
- B
- Old shares per batch in the ratio.
- value
- Position worth, identical before and after.
Fractional new shares usually cash out instead of issuing. Option contracts adjust by the same ratio through the clearinghouse, keeping their economics whole.
Worked example
Example: 10 shares at $100, 2-for-1
Defaults: shares 10, price 100, ratio 2-for-1.
- New shares: 10 x 2 / 1 = 20.0000.
- New price: 100 x 1 / 2 = $50.00.
- Before: 10 x 100 = $1,000.00.
- After: 20 x 50 = $1,000.00, identical.
- Tool shows 20.0000 shares, $50.00, $1,000.00 before = after.
Reference table
| Split | Result | Value |
|---|---|---|
| 10 at $100, 2-for-1 | 20 at $50.00 | $1,000.00 |
| 100 at $90, 3-for-1 | 300 at $30.00 | $9,000.00 |
| 5,000 at $0.10, 1-for-200 | 25 at $20.00 | $500.00 |
Limits
- Math only; markets reprice after the effective date.
- Fractional shares cash out with tax paperwork.
- Cost basis per share adjusts with price; total basis holds.
- Reverse splits often flag distress: read the filing.
Common mistakes
- Thinking splits create value out of nothing.
- Forgetting basis per share changes with price.
- Misreading 1-for-200 backwards as a windfall.
- Trading the announcement without reading terms.
- Ignoring reverse split distress signals.
Try it yourself
Quick checks. Answers sit tucked under each question.
5,000 at $0.10 in a 1-for-200 reverse split?
25.0000 shares at $20.00, still $500.00.
100 at $90 in a 3-for-1?
300.0000 at $30.00, still $9,000.00.
Does ownership share change?
No. Every holder scales by the same ratio, so percentages hold.
Questions
What happens to my shares in a split?
Count multiplies and price divides by the ratio. Value stays put.
What is a reverse split?
Fewer shares at a higher price, like 1-for-200: 5,000 at $0.10 become 25 at $20.
Do splits make money?
No. They reslice value; later price moves decide everything after.
What about my cost basis?
Per share basis divides with price; total basis never moves.
Why do companies split?
Lower prices feel accessible; reverse splits defend listing minimums.
Fractional shares?
Usually paid in cash instead of issuing fractions.