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Stock Split Calculator

Convert a holding through forward or reverse stock splits: new share count, adjusted cost basis per share, split-adjusted price and cash in lieu of fractions.

Splits to apply, in order

#1
for

A 3-for-1 forward split turns 1 share into 3. A reverse split is entered the other way round: 1 for 10 turns 10 shares into 1.

300
Shares after
$20.0000
Adjusted basis / share
$30.0000
Adjusted price / share
$0.00
Cash in lieu

Before and after, split by split

SplitTypeSharesBasis / sharePrice / share
StartHolding before any split100$60.0000$90.0000
3-for-1Forward split300$20.0000$30.0000

Position summary

Combined split factor×3.000000
Exact shares after all splits300.000000
Whole shares kept300
Fractional share left over0.000000
Total cost basis (unchanged by a split)$6,000.00
Position value after the split$9,000.00

A split multiplies your share count by the ratio and divides the cost basis and price by the same ratio, so the total value and total cost basis stay the same. Worked check: 100 shares with a $60 basis through a 3-for-1 split become 300 shares with a $20 basis. Cash in lieu is valued at the post-split price you entered. This is arithmetic for record-keeping, not tax advice.

What is the Stock Split Calculator?

The ByteTools Stock Split Calculator shows exactly what a split does to your position. Enter the shares you hold, your cost basis per share and the current price, then add one or more splits — 3-for-1, 2-for-1, 1-for-10 reverse — and it recalculates the share count, the adjusted basis and the split-adjusted price at every step.

  • Handles forward splits and reverse splits from the same ratio boxes
  • Chains several splits in sequence with a per-step before-and-after table
  • Adjusted cost basis per share and unchanged total basis shown together
  • Split-adjusted share price for comparing old charts with today
  • Optional cash in lieu of the leftover fractional share
  • Local, private and free — no sign-up and nothing uploaded

How to use the Stock Split Calculator

  1. 1

    Enter the shares you hold before the split, your cost basis per share and the current share price.

  2. 2

    Add a split row for each corporate action, entering the new-share and old-share sides of the ratio.

  3. 3

    Use Add split to chain several splits in the order they happened.

  4. 4

    Tick or untick the cash-in-lieu option depending on whether your broker cashes out fractional shares.

  5. 5

    Read the adjusted share count, basis and price in the tiles, then check the step-by-step and summary tables.

About the Stock Split Calculator

The ByteTools Stock Split Calculator shows exactly what a split does to your position. Enter the shares you hold, your cost basis per share and the current price, then add one or more splits — 3-for-1, 2-for-1, 1-for-10 reverse — and it recalculates the share count, the adjusted basis and the split-adjusted price at every step.

It is built for investors updating records after a corporate action, and for anyone comparing a pre-split price chart with today's quote. Splits can be chained in sequence, so a company that split twice in a decade can be worked through in one go, with a before-and-after table for each event.

Nothing about a split changes what your position is worth or what you paid in total, and the summary makes that plain by showing the unchanged total cost basis. Everything is computed in your browser with no uploads. This is arithmetic for record-keeping, not tax advice.

Frequently asked questions

What happens to my cost basis in a stock split?

Your total cost basis does not change, but it spreads across more shares. After a 3-for-1 split, 100 shares with a $60 basis become 300 shares with a $20 basis, and the total stays at $6,000.

How do I calculate shares after a stock split?

Multiply your share count by the split ratio. A 3-for-1 split multiplies by three; a 1-for-10 reverse split multiplies by 0.1, turning 250 shares into 25. This calculator applies each ratio in order if a stock has split more than once.

Does a stock split make me money?

No. On the day of the split the price falls by the same factor the share count rises by, so the value of your position is unchanged. Splits mainly affect liquidity, option contract sizes and how affordable a single share looks.

What is cash in lieu of fractional shares?

When a split leaves you with a partial share, many brokers sell it and pay you the cash instead. Ticking the option here rounds your holding down to whole shares and values the leftover fraction at the post-split price you entered.

How does a reverse stock split work?

A reverse split combines shares, so 1-for-10 turns every ten shares into one and multiplies the price and your per-share cost basis by ten. Companies usually do this to lift a share price back above an exchange's minimum listing requirement.

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