Dollar-Cost Averaging Calculator
The shares a fixed amount buys each period, your average cost against the average price, and how it compares with investing everything at the start.
Result
Average cost per share: $47.82
On the prices you enter. It shows what averaging did on those prices, not what a market will do.
- Average price per share
- $48.33
- Shares bought
- 62.7341
- Total invested
- $3,000.00
- Value at the last price
- $3,262.17
- If invested all at the first price
- $3,120.00
- Return
- 8.7391%
https://calcgallery.com/investment-returns/dollar-cost-averaging-calculator/
Results are arithmetic on the returns, rates and horizons you enter, not a forecast and not investment, tax or retirement advice. The site supplies no expected return, inflation rate, contribution limit, tax rate or withdrawal rate. Real returns vary from year to year, and fees, taxes and the order of returns all change the outcome. Check anything that matters with a qualified adviser. Read the full disclaimer
How to use the Dollar-Cost Averaging Calculator
- Enter the amount you invest each period.
- Enter the price in each period, or a starting price with a steady change per period.
- Compare your average cost per share with the average price, and your result with investing everything at the start.
The arithmetic
Each period, the amount buys amount ÷ price shares. Over n periods you invest n × amount and hold the sum of the shares, so your average cost per share is the total invested divided by the total shares. That is exactly the harmonic mean of the prices.
A guarantee, and its limit
The arithmetic-harmonic mean inequality guarantees that the harmonic mean of positive numbers is at or below their arithmetic mean. So averaging always buys at an average cost no higher than the average price. The page is tested for this on hundreds of random price series.
What it does not guarantee is a better result than investing everything at once. If prices rise, money invested earlier buys more cheaply than money invested later, whatever the averaging does. Both statements are true, and the page shows both so it stays a calculator rather than an argument.
With your numbers
- $3,000.00 bought 62.7341 shares
- Average cost = $3,000.00 ÷ 62.7341 = $47.82, against an average price of $48.33
Quick reference
On the prices you enter. It shows what averaging did on those prices, not what a market will do.
| Example | Average cost per share |
|---|---|
| 500 at 50, 45, 40, 48, 55, 52 | $47.82 |
| 1,000 at 100 then 50 | $66.67 |
| 500 at a flat 50 | $50.00 |
| 600 at 10, 20, 30, 40 | $19.20 |
| 500 a month, price rising 1% a month | $55.93 |
| 500 a month, price falling 2% a month | $44.63 |
Common questions about the Dollar-Cost Averaging Calculator
- Why is my average cost lower than the average price?
- Because a fixed amount buys more shares when the price is low and fewer when it is high, so the low prices carry more weight. Mathematically, your average cost is the harmonic mean of the prices, which is never above their ordinary average and equal only when every price is the same. Investing 1,000 at 100 and then 1,000 at 50 gives an average price of 75 but an average cost of 66.67.
- Is dollar-cost averaging better than a lump sum?
- Not in a rising market. Buying at 10, 20, 30 and 40 gives an average cost of 19.20 against an average price of 25, yet 2,400 invested all at 10 would end worth 9,600 against 5,000 for averaging. Averaging lowers your cost relative to the average price; it does not beat buying early when prices go up. Its real value is reducing the risk of putting everything in at a peak.
- What if the price falls throughout?
- Then averaging buys more and more shares as the price drops, and it ends ahead of a lump sum at the first price, though both lose money.
- Do fees matter?
- Yes, with small regular amounts. A fixed fee on each purchase is a larger share of a small investment. This page assumes no fees.