Enter how many shares you own, the price and the split ratio to see your new share count, the adjusted price per share and cost basis, and what happens to any fractional share. Works for forward splits like 3-for-1 and reverse splits like 1-for-10.
Last updated:
$
Split ratio
The first number: 3 in a 3-for-1 split.
The second number: 10 in a 1-for-10 reverse split.
Cost basis & fractions (optional)
$
Fractional shares
Enter your values to see the result.
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How to use the Stock Split Calculator
Enter your shares and the share price before the split.
Type the split ratio: new shares for every old shares, e.g. 3 and 1 for a 3-for-1 split, or 1 and 10 for a 1-for-10 reverse split (or tap a preset).
Optionally add your cost basis, total or per share.
Choose how fractions are handled: paid as cash or kept by your broker.
Read the new shares, price and basis, and compare other ratios in the table.
Stock split formulas
For an A-for-B split the split factor is k = A ÷ B.
New shares = old shares × k
New price = old price ÷ k
New cost basis per share = total cost basis ÷ new shares (total basis is unchanged)
Cash in lieu = fractional share × new price
Example: 25 shares in a 1-for-10 reverse split give 2.5 shares. You keep 2 whole shares, and the 0.5 share may be paid out in cash.
Common split ratios
Split
Factor
100 shares become
$300 price becomes
2-for-1
2
200
$150.00
3-for-2
1.5
150
$200.00
3-for-1
3
300
$100.00
4-for-1
4
400
$75.00
10-for-1
10
1,000
$30.00
20-for-1
20
2,000
$15.00
1-for-5 (reverse)
0.2
20
$1,500.00
1-for-10 (reverse)
0.1
10
$3,000.00
Frequently asked questions
How do you calculate shares after a stock split?
Multiply the shares you own by the split ratio. In an A-for-B split the factor is A ÷ B, so 150 shares in a 3-for-1 split become 150 × 3 = 450 shares, and 150 shares in a 1-for-10 reverse split become 15 shares.
What happens to the share price after a split?
The price is divided by the same factor, so the total value stays the same at the moment of the split. A $420 stock after a 3-for-1 split trades around $140. The market can of course move the price afterwards.
Does a stock split change my cost basis?
Your total cost basis stays the same; it is spread over the new number of shares. In the US a split is generally not a taxable event. If you paid $30,000 for 150 shares and get 450 after the split, your basis becomes $66.67 per share. Check your broker statements and local tax rules.
What is a reverse stock split?
A reverse split combines shares into fewer, higher-priced shares, such as 1-for-10. Companies often do this to lift a low share price, for example to meet an exchange's minimum listing price. Your ownership percentage and value do not change because of the split itself.
What happens to fractional shares in a split?
If the new share count is not a whole number, many companies pay cash in lieu of the fraction, based on the market price. Some brokers that support fractional shares let you keep it. A cash payment for a fraction can count as a small sale for tax purposes.
Does a split make me richer?
No. A split is like cutting a pizza into more slices: you have more pieces, each worth less, and the same total. It can make shares easier to buy in whole units, but it does not change the company's value.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.