Stock Split Calculator
Calculate the adjusted share count, post-split stock price, and cost basis per share following any forward or reverse stock split.
Total market value unchanged: $36,000 before and after split.
Stock Split Calculator - Forward & Reverse Split Share Adjustments: Calculate adjusted share count, post-split stock price, and cost basis per share following any stock split. Free, private, and simple to use in your browser.
How to Use the Stock Split Calculator
Select Split Direction
Choose between a Forward Stock Split (e.g. 2:1, 4:1) or Reverse Stock Split (e.g. 1:5, 1:10).
Specify Split Ratio
Select standard exchange presets or type custom X-for-Y share ratio parameters.
Input Existing Holdings
Enter your pre-split share balance, current market stock price, and tax cost basis per share.
Review Adjusted Metrics
Inspect post-split share counts, adjusted trading prices, and new IRS tax cost basis.
Financial Planning Guide: Stock Splits Explained: Forward vs Reverse Corporate Actions
A stock split is a corporate action in which a public corporation alters the total number of its outstanding shares while maintaining the company's overall market capitalization. In a standard forward stock split (such as Apple's 4-for-1 or Tesla's 3-for-1 splits), the company increases the number of shares while decreasing the per-share market price proportionally. For example, in a 2-for-1 split, every stockholder receives two shares for each share previously held, while the stock price is cut in half.
Forward splits are executed primarily to enhance liquidity and make shares psychologically more accessible to retail investors, particularly when an individual share price climbs to hundreds or thousands of dollars. Crucially, a stock split does not create or destroy shareholder value. If you hold 100 shares of a company trading at $300 ($30,000 total value) that undergoes a 3-for-1 split, you will hold 300 shares trading at $100 ($30,000 total value).
Conversely, a reverse stock split (such as 1-for-10) consolidates existing shares into fewer, higher-priced shares. Reverse splits are typically deployed by struggling companies whose share prices have fallen below the $1.00 minimum bid threshold required to maintain listing compliance on major exchanges like NASDAQ or the NYSE.
From a tax accounting standpoint, stock splits are non-taxable corporate reorganizations under US tax law. However, you must adjust your cost basis per share by dividing your original cost basis by the split ratio, ensuring your tax records remain accurate when shares are eventually liquidated.
Key Benefits & Features
Forward & Reverse Support
Seamlessly handles both common expansion splits and distressed contraction reverse splits.
IRS Cost Basis Adjustment
Accurately computes adjusted tax cost basis per share to avoid tax filing discrepancies.
Value Invariance Check
Explicitly verifies that total position market valuation and equity remain perfectly conserved.
Popular Presets
One-click presets for 2:1, 3:1, 4:1, 10:1 forward splits and 1:5, 1:10 reverse splits.
Custom Ratio Engine
Supports arbitrary odd-lot corporate splits including 3-for-2 and 7-for-4 reorganizations.
Private & Secure
Zero portfolio data leaves your machine; calculation runs purely on client hardware.
Is a stock split a taxable event?
No. In the United States and most jurisdictions, stock splits are not taxable events because your total wealth and proportional ownership of the company have not changed. You only pay taxes when you eventually sell shares.
What happens to my cost basis after a stock split?
Your total cost basis remains identical, but your cost basis per share decreases in a forward split (or increases in a reverse split). In a 2-for-1 split, your cost basis per share is cut in half.
What happens if a reverse split results in fractional shares?
Most brokerage firms liquidate fractional shares resulting from reverse splits and deposit cash-in-lieu into your investment account. This cash-in-lieu payout is a taxable transaction.
Do stock splits affect dividend payouts?
Yes, per-share dividends are divided by the split ratio. If a company paying $2.00/share annually does a 2-for-1 split, the new annual dividend becomes $1.00/share. Because you own twice as many shares, your total dividend cash received remains identical.
Do stock prices go up after a stock split?
Historically, companies that execute forward stock splits often experience temporary bullish sentiment due to retail interest. However, over the long term, share prices reflect underlying corporate earnings and fundamentals.
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Frequently Asked Questions
Yes, Stock Split Calculator – Forward & Reverse Split Share Adjustments is 100% completely free to use online with no hidden subscription fees, accounts, or software installation required.
Absolutely. All processing occurs securely within your web browser. Your inputs, calculations, and files are never stored, logged, or uploaded to external servers.
Yes. Stock Split Calculator – Forward & Reverse Split Share Adjustments is fully responsive and optimized for seamless use across smartphones, tablets, laptops, and desktop computers.
No plugins, extensions, or downloads are required. Stock Split Calculator – Forward & Reverse Split Share Adjustments operates directly in any standard, modern web browser.