Stock Split Calculator
Calculate your post-split share count, adjusted price, and cost basis for any forward or reverse stock split. Supports ratios from 2:1 to 25:1 forward splits and 1:2 to 1:20 reverse splits, including notable splits like Apple 4:1, Tesla 5:1, NVIDIA 10:1, Amazon 20:1, and Booking 25:1.
Stock Split Calculator
Calculate your new share count, price, and cost basis after a stock split
Frequently Asked Questions
What is a stock split?
A stock split is a corporate action where a company divides its existing shares into multiple new shares to increase the number of shares outstanding. The total market capitalization remains the same because the price per share adjusts proportionally. For example, in a 2-for-1 split, each share becomes two shares at half the original price. Companies typically split their stock to make shares more affordable and increase liquidity for retail investors.
How does a stock split affect share price?
A stock split reduces the price per share proportionally to the split ratio while increasing the number of shares. In a 3-for-1 split, a $300 stock becomes $100 per share, but you hold three times as many shares. Your total investment value remains exactly the same immediately after the split. Over time, the increased accessibility and liquidity can sometimes lead to price appreciation, though this is not guaranteed.
What is a 2-for-1 stock split?
A 2-for-1 (2:1) stock split means every share you own becomes two shares, each worth half the original price. If you owned 100 shares at $200 each ($20,000 total), after the split you would own 200 shares at $100 each (still $20,000 total). This is the most common split ratio, though companies like Apple and Tesla have used larger ratios such as 4-for-1 and 5-for-1 splits.
Do I lose money in a stock split?
No, you do not lose money in a stock split. The total value of your investment remains the same immediately after the split. You receive more shares at a proportionally lower price, so the math balances out perfectly. For example, 50 shares at $400 each equals $20,000, and after a 4-for-1 split, 200 shares at $100 each still equals $20,000. Your ownership percentage in the company also stays the same.
What is a reverse stock split?
A reverse stock split consolidates multiple shares into fewer shares at a higher price per share. In a 1-for-10 reverse split, every 10 shares become 1 share worth 10 times as much. Companies use reverse splits to increase their share price, often to meet stock exchange minimum price requirements or to appear more attractive to institutional investors. Unlike forward splits, reverse splits are sometimes viewed negatively by the market.
Why do companies split their stock?
Companies split their stock primarily to make shares more affordable for retail investors and increase trading liquidity. A lower share price attracts more individual investors who may not want to buy a single share priced at hundreds or thousands of dollars. Increased liquidity can narrow bid-ask spreads and reduce trading costs. Some companies also split to qualify for price-weighted indexes like the Dow Jones Industrial Average.
How do I calculate shares after a split?
To calculate shares after a split, multiply your current shares by the split ratio. For a forward split like 3-for-1, multiply shares by 3. For a reverse split like 1-for-5, divide shares by 5. The formula is: New Shares = Current Shares x (Split Ratio Numerator / Split Ratio Denominator). For example, 150 shares with a 4-for-1 split gives you 150 x 4 = 600 shares. The new price per share equals the old price divided by the same ratio.
How do I calculate my new cost basis after a stock split?
Adjusted Cost Basis = Original Purchase Price ÷ (Split Ratio). For a 4:1 split on shares bought at $400, new cost basis = $400 ÷ 4 = $100 per share. Your total cost remains unchanged; only the per-share basis adjusts. Track this for capital gains tax purposes.
Do I owe taxes on a stock split?
No, stock splits are not taxable events in the US. The IRS treats them as adjustments, not sales. However, your cost basis per share changes, which affects taxes when you eventually sell. Cash received in lieu of fractional shares during a reverse split may be taxable.
What happens to fractional shares in a reverse split?
If a reverse split creates fractional shares (e.g., 15 shares in a 1:10 reverse split = 1.5 shares), your broker typically either sells the fractional portion and pays you cash, or rounds to the nearest whole share. Cash-in-lieu payments are treated as taxable capital gains.
Is a reverse stock split good or bad?
It depends on context. Companies often use reverse splits to meet exchange minimum price requirements ($1 for NYSE/NASDAQ), which can signal financial trouble. However, some healthy companies reverse split to attract institutional investors or reduce share count. Research the company’s fundamentals and reasons for the split.
How does a stock split affect dividends?
Dividends per share are adjusted proportionally after a split. In a 2:1 split, if the dividend was $2/share, it becomes $1/share. Since you have twice as many shares, your total dividend income stays the same. Companies may later increase the adjusted dividend, which is a genuine raise.
How to Calculate a Stock Split
A stock split changes the number of shares you own and the price per share, but your total investment value stays the same. Here are the three formulas you need:
New Share Count
New Shares = Current Shares × (Split Ratio)
For a 4:1 split with 100 shares: 100 × 4 = 400 shares
New Price Per Share
New Price = Current Price ÷ (Split Ratio)
For a 4:1 split at $500/share: $500 ÷ 4 = $125/share
Adjusted Cost Basis
Adjusted Cost Basis = Purchase Price ÷ (Split Ratio)
Bought at $400, 4:1 split: $400 ÷ 4 = $100 per share cost basis
Forward vs Reverse Stock Split
Forward splits increase shares and lower the price. Reverse splits do the opposite. The table below compares the key differences:
| Feature | Forward Split | Reverse Split |
|---|---|---|
| Share count | Increases | Decreases |
| Price per share | Decreases | Increases |
| Total value | Unchanged | Unchanged |
| Common ratios | 2:1, 3:1, 4:1, 10:1, 20:1 | 1:2, 1:5, 1:10, 1:20 |
| Signal | Often positive (high growth) | Often negative (compliance) |
| Example companies | Apple, NVIDIA, Amazon | Struggling companies, SPACs |
Recent Notable Stock Splits
Major tech and growth companies have executed large stock splits in recent years to make their shares more accessible to retail investors:
| Company | Symbol | Ratio | Year | Pre-Split Price |
|---|---|---|---|---|
| Apple | AAPL | 4:1 | 2020 | ~$500 |
| Tesla | TSLA | 5:1 | 2020 | ~$2,200 |
| Tesla | TSLA | 3:1 | 2022 | ~$900 |
| Amazon | AMZN | 20:1 | 2022 | ~$2,800 |
| Alphabet | GOOGL | 20:1 | 2022 | ~$2,800 |
| NVIDIA | NVDA | 10:1 | 2024 | ~$1,200 |
| Netflix | NFLX | 10:1 | 2025 | ~$2,000 |
| Booking Holdings | BKNG | 25:1 | 2026 | ~$5,000 |
Cost Basis After a Stock Split
When a stock splits, your cost basis per share adjusts proportionally while your total cost stays the same. This matters for calculating capital gains when you sell.
Worked Example: Apple 4:1 Split (2020)
- You bought 50 shares of AAPL at $300 each (total cost: $15,000)
- Apple announces a 4:1 stock split
- After the split: 50 × 4 = 200 shares
- Adjusted cost basis: $300 ÷ 4 = $75 per share
- Total cost basis: 200 × $75 = $15,000 (unchanged)
- If you sell at $150/share, your gain per share = $150 - $75 = $75
Tax Implications of Stock Splits
Forward Splits
Forward stock splits are not taxable events. The IRS treats them as a reclassification of existing shares, not a disposition. You simply adjust your cost basis per share and holding period remains unchanged. No Form 1099 is issued for the split itself.
Reverse Splits
Reverse stock splits are also not taxable events in most cases. However, if you receive cash in lieu of fractional shares (for example, 15 shares in a 1:10 reverse split creates 1.5 shares, and you receive cash for the 0.5 fractional share), that cash payment is treated as a taxable capital gain.
Record-keeping tip: Always update your cost basis records after a stock split. Your broker should adjust the cost basis automatically in your account, but verify the numbers match your records. Accurate cost basis tracking is essential for reporting capital gains and losses on your tax return (Schedule D).
What Happens to Fractional Shares
Reverse stock splits can create fractional shares when your share count does not divide evenly by the split ratio. For example, 75 shares in a 1:10 reverse split produces 7.5 shares.
How Brokers Handle Fractional Shares
- Cash-in-lieu: The broker sells the fractional portion on the open market and credits your account with cash. This is the most common approach.
- Rounding: Some brokers round up or down to the nearest whole share, though this is less common.
- Fractional share support: Brokers that support fractional shares may simply keep the fractional position in your account.
Cash-in-lieu payments are treated as taxable capital gains. The gain or loss is calculated as the cash received minus the cost basis of the fractional share. This amount is reported on Form 1099-B.
How Stock Splits Affect Dividends
Dividends per share adjust proportionally after a split, just like the stock price. Your total dividend income remains the same immediately after the split.
Example: 2:1 Split and Dividends
- Before split: 100 shares, $2.00 dividend per share = $200 total quarterly dividend
- After 2:1 split: 200 shares, $1.00 dividend per share = $200 total quarterly dividend
- Your total income is unchanged
If the company later increases the adjusted dividend (e.g., from $1.00 to $1.20 per share), that represents a genuine 20% dividend raise, separate from the split adjustment.