Stock Split Calculator
This calculator converts a forward or reverse stock split ratio into the expected post-split share count and share price for a given holding, and computes theoretical market capitalization and percent price change. It is intended for planning and illustrative purposes.
The tool supports any split described as a ratio (numerator:denominator). For example, a 1-for-5 reverse split is numerator 1 and denominator 5; a 2-for-1 forward split is numerator 2 and denominator 1.
Inputs
Results
Post-split shares
200
Post-split price
50
Market capitalization (theoretical)
$10,000.00
Price change (%)
400.00%
Change in share count
-800
| Output | Value | Unit |
|---|---|---|
| Post-split shares | 200 | — |
| Post-split price | 50 | USD |
| Market capitalization (theoretical) | $10,000.00 | USD |
| Price change (%) | 400.00% | — |
| Change in share count | -800 | — |
Visualization
Methodology
The calculator applies basic conservation of market value: a split changes the number of outstanding shares and the price per share inversely so that, in theory, market capitalization remains unchanged.
Inputs are multiplied or divided by the split ratio to produce post-split values. The calculator does not model market reactions, trading spreads, or corporate actions beyond the arithmetic split.
Rounding and fractional-share handling vary by broker and by exchange rules. Where brokers issue cash-in-lieu or round fractional shares, the real delivered position can differ from the pure arithmetic result; see the FAQs and citations for operational guidance.
Worked examples
Example 1: You own 1,000 shares at $10. A 1-for-5 reverse split (numerator=1, denominator=5) results in 200 shares at $50 (market cap remains $10,000).
Example 2: You own 100 shares at $2. A 2-for-1 forward split (numerator=2, denominator=1) results in 200 shares at $1 (market cap remains $200).
Key takeaways
This calculator provides theoretical post-split share counts and prices using arithmetic rules. It is not a trade order tool and does not execute trades.
Verify fractional-share settlement, rounding, and tax treatment with your broker or tax advisor before relying on settlement outcomes.
Further resources
Expert Q&A
Does a stock split change the total value of my holdings?
In theory no: market capitalization equals shares × price and remains the same immediately after a purely arithmetic split. However, market reactions and brokerage rounding can create small differences in realized value.
How are fractional shares handled after a split?
Brokers and custodians handle fractional shares differently: some issue cash-in-lieu, some round to whole shares, and some allow fractional share ownership. Use the rounding policy selector to model common outcomes, and check your broker's published policies for final settlement rules.
Does this calculator account for taxes or market movement?
No. This tool models only the arithmetic effect of the split. It does not estimate capital gains, tax treatment, or subsequent market price movement.
Is the result exact for corporate reporting?
The output is a mathematical estimate. Official reporting and broker account statements may include adjustments, withholding, or rounding as required by corporate action agents or exchange rules; always confirm with official notices from the issuer or registry.
Sources & citations
- National Institute of Standards and Technology (NIST) - Risk Management and Data Integrity principles — https://www.nist.gov
- International Organization for Standardization (ISO) - Risk and quality management standards — https://www.iso.org
- IEEE Standards Association - best practices for numeric accuracy and validation — https://standards.ieee.org
- Occupational Safety and Health Administration (OSHA) - operational safety and process controls (relevant for implementation standards) — https://www.osha.gov
- U.S. Securities and Exchange Commission - Corporate actions and investor bulletins — https://www.sec.gov