Stock Split Adjuster

The Split Math, Explained

Enter the split as a "New : Old" ratio. A forward split like 2-for-1 (New = 2, Old = 1) doubles your share count and halves the price per share. A reverse split like 1-for-10 (New = 1, Old = 10) does the opposite: it shrinks your share count to a tenth of what it was and multiplies the price per share by ten. The formulas behind both cases are the same:

• Post-Split Shares = Pre-Split Shares × (New ÷ Old)
• Post-Split Price = Pre-Split Price × (Old ÷ New)

Because one formula multiplies by New/Old and the other multiplies by its reciprocal, Old/New, the two effects cancel out exactly when you multiply shares by price again. That's the entire concept a stock split represents: your total position value is unchanged by the split itself.

Worked Examples

Forward split: You own 100 shares at $300 each ($30,000 total) and the company announces a 2-for-1 split. Post-split shares = 100 × (2 ÷ 1) = 200 shares. Post-split price = $300 × (1 ÷ 2) = $150. New total value = 200 × $150 = $30,000 — unchanged.

Reverse split: You own 1,000 shares at $2 each ($2,000 total) and the company does a 1-for-10 reverse split. Post-split shares = 1,000 × (1 ÷ 10) = 100 shares. Post-split price = $2 × (10 ÷ 1) = $20. New total value = 100 × $20 = $2,000 — again unchanged. Companies typically use reverse splits to push a low, sometimes penny-stock price back above an exchange's minimum listing threshold.

Why This Confuses People

A stock split feels like something happened to your wealth because your account suddenly shows a very different share count and price, but nothing about the underlying business, its earnings, or its market capitalization changed. The company simply redivided the same total equity value into a different number of slices. Any real change in the stock's price after a split announcement is driven by market sentiment or trading dynamics around the announcement — not by the mechanics of the split itself.

Frequently Asked Questions

Q: What happens to fractional shares from an odd split ratio?
A: Splits like 3-for-2 can leave you with a fractional share if your pre-split count isn't evenly divisible. Most brokers don't issue partial shares in this situation; instead they sell the fractional amount on your behalf and deposit the cash value into your account, commonly called "cash-in-lieu."

Q: Does a split change my ownership percentage of the company?
A: No. Every shareholder's shares are adjusted by the same ratio, so your percentage ownership of the company stays exactly the same before and after.

Q: Do open limit orders or options contracts need to be adjusted too?
A: Yes, brokers and options exchanges automatically adjust outstanding orders, strike prices, and contract sizes to reflect the new share count, so the economic value of those positions is preserved just like your underlying shares.