Dollar-Cost Averaging Calculator
Units bought, average cost and lump-sum comparison for regular investing.
About this tool
Enter the price at each purchase date, such as month-end prices, the fixed amount you invest each time and any purchase fee. The calculator shows the total invested, units bought, average cost per unit against the average price, the value at the last price and what the same money would be worth if invested in one go at the first price, with a period-by-period table.
How dollar-cost averaging works
Dollar-cost averaging, or pound-cost averaging, means investing the same amount at regular intervals whatever the price. A fixed amount buys more units when the price is low and fewer when it is high, so your average cost per unit is the harmonic mean of the prices, which is always at or below their simple average. In the example, investing 200 a month while a price falls from 50 to 35 and then recovers to 65 gives an average cost of about 49.33, against an average price of 51, and turns 2,400 into about 3,163. A lump sum at the first price would have reached 3,120. Averaging helped there because prices dipped first. When prices mostly rise, investing a lump sum at the start usually does better, and studies of past markets find that happens around two-thirds of the time. The real benefit of averaging is behavioural: it removes the pressure to time the market, reduces regret and suits saving from a monthly income. Honest limits: this is a backward-looking illustration of prices you enter, not a forecast. Not investment advice. The stock average calculator, the CAGR calculator and the compound interest calculator are related. Compound interest, explained with real numbers explains long-term growth.
Frequently asked questions
What is dollar-cost averaging?
Investing a fixed amount at regular intervals regardless of price, so you buy more when prices are low and less when they are high.
Is dollar-cost averaging better than a lump sum?
Not usually in rising markets: lump sums have historically won about two-thirds of the time. DCA reduces timing risk and regret.
Why is my average cost lower than the average price?
Because a fixed amount buys more units at low prices, the average cost is a harmonic mean, which is never higher than the simple average.
Is my data saved?
No. The calculation runs in your browser and nothing is stored or sent.