Monthly Stock Buying Calculator (buy every month at real prices: average cost & return)

How it works

Each month the fixed amount is added to the cash on hand and as many shares as possible are bought at that month’s price (whole shares, or fractions if allowed). Because the amount is fixed, you buy more shares when the price is low and fewer when it is high, so the average cost per share = (money spent ÷ shares owned) is the harmonic-style average of the prices and is never above their simple average. Value now = shares owned × current price + cash not yet invested. Return = (value − total invested) ÷ total invested. Fees, taxes and dividends are not included. Independent calculator, not affiliated with any company. Not investment advice; past returns do not guarantee future returns.

⚠ Estimates for information only — not financial advice.

FAQ

Is buying every month better than buying all at once?

Not always. In a market that mostly rises, investing a lump sum early often ends higher; monthly buying lowers the risk of bad timing and suits money you earn each month.

Why is my average cost lower than the average price?

A fixed amount buys more shares when the price is low, so low prices carry more weight in your average cost.

Checked 11 Nov 2026. Dollar-cost averaging arithmetic (fixed amount per period; average cost = total spent ÷ shares), e.g. Investor.gov (U.S. SEC), “Dollar Cost Averaging”. Prices: KRX Data Marketplace (data.krx.co.kr) closing prices you enter.