Skip to content
Finance Calc Kit
Investments

Stock Split Calculator

Calculate how a stock split affects your share count, price per share, and total portfolio value. Supports forward and reverse stock splits.

Stock split inputs

$

Portfolio value after split

$20,000.00

Stock splits do not change total investment value

New share count

200

Before: 100 shares

New price per share

$100.00

Before: $200.00

Forward split 2:1: split factor ×2.0000, +100 shares, portfolio value stays at $20,000.00.

Stock split calculation

Open to see each step from your inputs to the result.

  1. Multiply shares by the split factor

    New Shares=Original Shares×New RatioOld Ratio\text{New Shares} = \text{Original Shares} \times \frac{\text{New Ratio}}{\text{Old Ratio}}

  2. Divide price per share by the split factor

    New Price=Old PriceSplit Factor\text{New Price} = \frac{\text{Old Price}}{\text{Split Factor}}

  3. Confirm portfolio value is unchanged

    Portfolio Value=Shares×Price\text{Portfolio Value} = \text{Shares} \times \text{Price}

Report tool

What is a stock split?

A stock split is a corporate action in which a company increases or decreases its outstanding shares while adjusting the quoted price per share so total market capitalization stays the same. Your ownership percentage and portfolio value do not change on the split date. Only the share count and per-share price move in opposite directions.

Use this calculator to model forward splits (more shares, lower price) and reverse splits (fewer shares, higher price). When you eventually sell, adjusted cost basis feeds into the capital gains calculator. To see how per-share price relates to company size, pair results with the price per share calculator.

How a stock split works

Companies announce a split ratio such as 2-for-1 or 3-for-2. On the effective date, each existing share is replaced by the stated number of new shares, and the trading price is divided by the same factor. Reverse splits use the same math in the opposite direction.

Worked example: 2-for-1 forward split

Suppose you own 100 shares trading at $200 per share before a 2-for-1 forward split:

  • Before split: 100 shares × $200 = $20,000 portfolio value
  • After split: 200 shares × $100 = $20,000 portfolio value
  • Share count doubles, price halves, total value is unchanged

Stock split formulas

For a forward split with ratio new:old (for example 2:1 means two new shares for every one old share):

Split Factor=New RatioOld Ratio\text{Split Factor} = \frac{\text{New Ratio}}{\text{Old Ratio}}
New Shares=Original Shares×Split Factor\text{New Shares} = \text{Original Shares} \times \text{Split Factor}
New Price=Old PriceSplit Factor\text{New Price} = \frac{\text{Old Price}}{\text{Split Factor}}

For a reverse split, divide shares and multiply price by the split factor instead. A 1-for-5 reverse split turns 500 shares at $2 into 100 shares at $10, keeping the $1,000 position value intact.

Common split ratios

Split ratioTypeShare multiplierPrice divisor
2-for-1Forward2×÷ 2
3-for-1Forward3×÷ 3
3-for-2Forward1.5×÷ 1.5
1-for-5Reverse0.2×× 5
1-for-10Reverse0.1×× 10

Forward split vs reverse split

Forward stock split

  • Increases outstanding shares and lowers the quoted price
  • Often used when a stock price has risen and management wants broader retail access
  • Can improve liquidity and tighten bid-ask spreads

Reverse stock split

  • Reduces outstanding shares and raises the quoted price proportionally
  • Sometimes used to meet exchange minimum price listing requirements
  • Can signal financial stress, though context matters for each issuer

Cost basis after a split

Your total cost basis does not change, but cost basis per share adjusts with the split. If you bought 50 shares at $100 each ($5,000 total basis), a 2-for-1 split gives you 100 shares with $50 basis per share. When you sell, use the adjusted per-share basis to compute gain or loss.

What a stock split does not change

  • Market capitalization of the company
  • Your proportional ownership stake
  • Total portfolio value on the split effective date
  • Underlying fundamentals such as revenue, earnings, or cash flow

Frequently asked questions

What is a stock split?
A stock split divides each existing share into multiple new shares (forward split) or combines shares into fewer units (reverse split). The per-share price adjusts so total market value stays the same on the effective date.
How do I calculate shares after a stock split?
Multiply your original share count by the split factor. For a 3-for-1 split, new shares equal original shares × 3. For a 3-for-2 split, multiply by 1.5. Enter your position in the calculator above for any custom ratio.
Does a stock split change the value of my investment?
No. A split reallocates the same total value across more or fewer shares at a proportionally lower or higher price. Your portfolio value on the split date should match the value immediately before, aside from normal market movement.
What is a reverse stock split?
A reverse split reduces share count and raises price per share. A 1-for-10 reverse split converts every 10 shares into 1 share and multiplies the price by 10. Companies sometimes use reverse splits to satisfy minimum listing prices.
Do I owe taxes when my shares split?
No. A stock split is generally not a taxable event in the United States. Your cost basis per share adjusts proportionally, and taxes apply only when you sell shares at a gain or loss.
How does a split affect dividends per share?
Cash dividends per share are typically adjusted after a split so total payout to existing shareholders stays consistent with company policy. A $2.00 quarterly dividend before a 2-for-1 split often becomes $1.00 on twice as many shares.
Are my inputs saved on your servers?
No. All calculations run locally in your browser. Changing inputs updates the page URL so you can bookmark or share a specific scenario.

Resources and references

The formulas and methods in this calculator were checked against these independent sources.