Dollar-cost averaging calculator
Buying the same dollar amount every month feels simple. But what did it really cost you per share, and are you ahead or behind? Type the prices at each buy. See your true average cost, what it's worth now, and the price that gets you back to even.
| Buy | Price | Units bought | Total units | Put in so far |
|---|
How it works: each buy gets units = amount ÷ that day's price, so a low price buys more units. Average cost = total put in ÷ total units. Average price = the plain average of the prices. Value = total units × the last price. Gain or loss = value − total put in. Fees and dividends are left out. The prices are yours to type: this is the math on your inputs, not a forecast.
Why your average cost beats the average price
Each buy is the same dollars. When the price is low, those dollars buy more units. So the cheap buys count for more in your average, and your average cost lands below the plain average of the prices. That's the real edge of dollar-cost averaging: it's math, not magic. It does not make a falling price go back up. If the price ends below your average cost, you're down, the same as anyone else. The default example shows exactly that. More in dollar-cost averaging vs a lump sum.
What it's really good for
A plan you run on a set day takes the guessing out. You don't have to pick the bottom, and a bad week doesn't freeze you. Write down the amount and the day, and track every buy. My free trading templates keep the running total for you. If you buy different amounts each time, use the average cost calculator instead.
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