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Stock market calculators · Forward splits and reverse consolidations

Stock Split Calculator

Created by Arunangshu DasReviewed

Calculate theoretical post-split shares, reference price and position value. See the exact fractional remainder before settlement.

Use one security, one major currency and a supplied new-for-old ratio.

Pre-split position and new-for-old ratio

Enter one security in consistent share units. The ratio gives the number of new shares for each stated number of old shares.

Formatting only. Enter major currency units, including pounds for GBP.

Enter the shares you hold, including any fractional shares.

Use a price before the split adjustment. A purchase price, face value or split-adjusted quote describes a different input.

For a 1-for-10 reverse split, enter 1 here.

For a 1-for-10 reverse split, enter 10 here.

Theoretical position before settlement

Enter your position and split ratio, or load the worked example.

The whole and fractional components describe the exact theoretical entitlement. Actual shares and any cash depend on settlement terms. Market prices can move after a split.

The decimal share and price displays use up to 12 significant figures. Position value uses the unrounded calculation, so multiplying rounded display values can give a different amount.

Understand split ratios and fractional entitlements

Follow forward and reverse examples and learn why the theoretical share count can differ from the actual account credit.

Read the complete Stock Split guide

Formula and methodology

New shares = Q × N / O
New reference price = P × O / N
Modeled position value = Q × P.

Multiply Q by N/O for theoretical shares and multiply P by O/N for theoretical reference price. The reciprocal factors cancel in the unrounded product. The modeled position value is Q × P on either side. Divide the exact share numerator by its denominator to identify the whole component and fractional remainder.

Definitions

Q is the pre-split holding and P is its pre-split reference price per share. N-for-O means N new shares for every O old shares. N greater than O is a forward split. N below O is a reverse split or consolidation. Equal terms describe an identity conversion.

Verified worked examples

A 1-for-10 reverse split turns 103 shares at a pre-split reference price of 2.40 into 10.3 theoretical shares at 24 per share. The exact decomposition is 10 whole shares plus 3/10 of one share. The modeled value is 247.20 on either side before market movement or settlement. A 3-for-2 forward split turns 5 shares at 90 into 7.5 theoretical shares at 60, preserving 450.

Interpretation

The fraction is a mathematical entitlement before settlement. It does not indicate the number of shares credited or a cash amount. The theoretical reference price is a unit adjustment to the supplied quote. The market can trade at a different price.

Inputs and interpretation

Read the issuer notice to identify how many new shares replace the specified old shares. Enter the holding and a pre-split reference price in one major currency. Enter the two ratio terms separately and compare the decimal estimate with the exact whole and fractional components.

Assumptions and limitations

One security, consistent share units and one ratio. The model isolates the split before settlement and market movement. It does not reuse a price series that has already adjusted for the same split or infer a ratio from a face-value quote.

Supported domain and common mistakes

Shares and price accept explicit zero and values through 1e12, with 12 fractional places and 48 characters. Each ratio term is a positive whole number no greater than 1,000,000. Exact integer arithmetic preserves the remainder and modeled value. Decimal presentation starts from 80 significant digits and displays shares and price with up to 12 significant figures. Money is displayed to cents with a marker for tiny nonzero amounts.

Check ratio direction, share units and quote currency. An issuer notice might state the old and new terms in a different order from the form. Do not confuse face value, purchase cost and reference price. Do not multiply rounded displayed values to reconcile exact modeled value.

Frequently asked questions

Which number goes first in a stock split ratio?
Enter new shares first and old shares second. For a 1-for-10 consolidation, one new share replaces ten old shares, so the share multiplier is one tenth.
Does a stock split change the value of my position?
The split alone leaves modeled value unchanged when shares and reference price adjust by reciprocal factors. Actual market prices and settlement can change the value you observe.
How many shares do I have after a 1-for-10 reverse split?
Divide the opening shares by ten. For 103 shares, the theoretical answer is 10.3, or 10 plus 3/10. Check issuer and broker terms to determine what is credited.
Can the result be less than one share?
Yes. Two shares in a 1-for-3 reverse split produce exactly 2/3 of a theoretical share. The whole component is zero, but the fraction is still shown.
Can I enter zero or a 1-for-1 ratio?
Yes. Explicit zero shares or price produces zero modeled position value. A 1-for-1 ratio leaves both inputs unchanged. Both ratio terms must be positive whole numbers.
Does this calculate cash-in-lieu or cost basis?
No. It shows the exact theoretical fraction and a reference price adjustment. Actual payment, settlement and tax basis require issuer and account information.
Does selecting a different market convert my prices?
No. It changes currency labels and display formatting. Keep all input prices in the same major currency. For GBP, enter pounds rather than pence.

Sources and educational scope

Educational theoretical conversion before market movement and settlement. Excludes cash-in-lieu, delivered shares, broker rounding, live prices, tax basis, fees, FX, effective dates and eligibility. No personalized investment advice.

Reviewed . AI-assisted content under operator editorial responsibility; no independent expert financial review is claimed.

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