Stock Split Calculator

Compute post-split share count, price, and adjusted cost basis.

Current shares ownedOriginal cost per share ($)Current market price ($)

Split ratio (new)Split ratio (old)

New share count

300.00

Adj. cost per share

$100.00

Adj. market price

$106.67

Total value (same)

$32000.00

What this measures

A stock split increases share count and proportionally lowers price per share — total market value and total cost basis are unchanged. Splits are cosmetic but matter for cost-basis tracking, options contracts, and lot-level bookkeeping in a brokerage account. Reverse splits work the same in reverse.

Formula & example

For a 2-for-1 split: shares × 2, price ÷ 2, per-share cost basis ÷ 2. For a 3-for-2 split: shares × 1.5, price ÷ 1.5. Enter your original shares, purchase price, and the split ratio. The calculator shows new totals plus the adjusted per-share cost basis you'll report to your broker.