Why Use This Stock Split Calculator
Stock splits can be confusing. Our Stock Split Calculator helps you:
- 📊 Calculate New Share Count — know exactly how many shares you’ll hold after a split.
- 💰 Adjust Cost Basis — see your new cost per share after the split.
- 🔄 Forward & Reverse Splits — handles both types of splits.
- 📈 Visual Comparison — see before and after side by side.
- 🔒 100% Private — all calculations run locally in your browser.
What Is a Stock Split?
A stock split is when a company divides its existing shares into multiple shares to increase liquidity and make shares more affordable. The total value of your investment stays the same.
| Split Type | Example | Shares Before | Shares After | Price Before | Price After |
|---|---|---|---|---|---|
| Forward Split | 2:1 | 100 | 200 | $50 | $25 |
| Reverse Split | 1:2 | 100 | 50 | $50 | $100 |
The Stock Split Formula
New Shares = Current Shares × Split Ratio
Adjusted Cost Per Share = Total Cost Basis ÷ New Shares
Example (2:1 Forward Split):
| Variable | Value |
|---|---|
| Current Shares | 100 |
| Split Ratio | 2 |
| Total Cost Basis | $5,000 |
| New Shares | 100 × 2 = 200 |
| Adjusted Cost Per Share | $5,000 ÷ 200 = $25 |
Example (1:2 Reverse Split):
| Variable | Value |
|---|---|
| Current Shares | 100 |
| Split Ratio | 0.5 |
| Total Cost Basis | $5,000 |
| New Shares | 100 × 0.5 = 50 |
| Adjusted Cost Per Share | $5,000 ÷ 50 = $100 |
How to Use This Stock Split Calculator
- Enter your current shares held — how many shares you own today.
- Enter your total cost basis — your original total investment amount.
- Enter the split ratio — 2 for a 2:1 forward split, 0.5 for a 1:2 reverse split.
- View your results — see your new shares, adjusted cost per share, and split type.
The tool updates instantly as you adjust any input — no “Calculate” button required.
Stock Split Examples
| Scenario | Shares | Cost Basis | Ratio | New Shares | New Cost/Share |
|---|---|---|---|---|---|
| 2:1 Split | 100 | $5,000 | 2 | 200 | $25.00 |
| 3:1 Split | 100 | $5,000 | 3 | 300 | $16.67 |
| 1:2 Reverse | 100 | $5,000 | 0.5 | 50 | $100.00 |
| 1:5 Reverse | 100 | $5,000 | 0.2 | 20 | $250.00 |
Frequently Asked Questions
What is a stock split?
A stock split is when a company divides its existing shares into multiple shares to increase liquidity. The total value of your investment stays the same, but the number of shares increases and the price per share decreases proportionally.
What is a reverse stock split?
A reverse stock split is when a company combines multiple shares into one share. The total value of your investment stays the same, but the number of shares decreases and the price per share increases proportionally.
How is the new share count calculated?
New Shares = Current Shares × Split Ratio. For a 2:1 forward split with 100 shares, new shares = 200. For a 1:2 reverse split with 100 shares, new shares = 50.
How is the adjusted cost per share calculated?
Adjusted Cost Per Share = Total Cost Basis ÷ New Shares. The total cost basis remains unchanged in a stock split.
Does a stock split affect my total cost basis?
No. The total cost basis remains unchanged. Only the number of shares and the cost per share are adjusted.
Is my data stored anywhere?
No. All calculations run locally in your browser. No data is sent to any server.