Stock Split Calculator
Calculate your new share count and price per share after a stock split or reverse stock split.
See how splits affect your holdings.
How Stock Splits Work
A stock split increases the number of shares outstanding while proportionally decreasing the price per share. The total market capitalization remains unchanged — you have more pieces of the same pie. Companies split stocks to make shares more accessible to retail investors.
Forward split formula:
New Price = Old Price ÷ Split Ratio New Shares = Old Shares × Split Ratio
Worked example — 3-for-1 split:
- Pre-split price: $450 per share
- Pre-split shares owned: 20
- Split ratio: 3:1
New price = $450 ÷ 3 = $150 per share New shares = 20 × 3 = 60 shares Total value before: 20 × $450 = $9,000 Total value after: 60 × $150 = $9,000 (unchanged)
Reverse split formula (company consolidates shares):
New Price = Old Price × Reverse Ratio New Shares = Old Shares ÷ Reverse Ratio
Example — 1-for-10 reverse split:
A stock at $0.80 does a 1-for-10 reverse split:
New price = $0.80 × 10 = $8.00 If you held 1,000 shares: new holding = 100 shares
Reverse splits are usually a warning sign — companies do them to avoid being delisted from exchanges that require minimum stock prices (often $1.00 for NASDAQ).
Historical notable splits:
- Apple: 7-for-1 in 2014, 4-for-1 in 2020
- Tesla: 5-for-1 in 2020, 3-for-1 in 2022
- Amazon: 20-for-1 in 2022 (first split since 1999)
- Berkshire Hathaway Class B: 50-for-1 in 2010
Cost basis adjustment:
After a split, your cost basis per share adjusts proportionally — your total cost basis and any capital gains calculations remain unchanged.