Each purchase
| # | Price | Units bought | Total units |
|---|
Your average cost is lower than the simple average of prices, because a fixed amount buys more units when prices are low. Results ignore taxes. Past prices don’t predict future returns. For education only, not investment advice.
What this dollar-cost averaging calculator does
Dollar-cost averaging (DCA) means investing a fixed amount at regular intervals, whatever the price. This dollar-cost averaging calculator works out what your regular purchases have actually achieved. Enter the amount you invest each time and the price at each purchase, and it shows:
- your average cost per unit
- the total invested and units bought
- the value today and your profit or loss
- how your result compares with investing everything at the first price
It works for shares, funds, ETFs and crypto.
How to use it
- Amount invested each time: for example, $100 a month.
- Fee per purchase: as a percentage, if your platform charges one. Use 0 if not.
- Price at each purchase: type or paste the prices, separated by commas, spaces or new lines.
- Price today: the current price, to work out your value and profit.
Open Each purchase to see how many units every buy added.
Why your average cost is lower than the average price
With a fixed amount, you automatically buy more units when prices are low and fewer when they're high. So your average cost per unit ends up below the simple average of the prices you paid.
Example: $100 a month at prices of $50, $45, $40, $38, $42, $48, $55 and $60, with a 0.5% fee:
- Simple average of prices: $47.25
- Your average cost per unit: about $46.47
- Value at $60: about $1,033 on $800 invested, a gain of about 29%
The formula
Average cost per unit = total amount invested ÷ total units bought
DCA vs lump sum
Investing everything at once tends to do better when prices rise steadily, because all your money is invested sooner. Regular investing tends to do better when prices fall and then recover, because you buy more units at low prices. The calculator shows both results for your own prices.
For a full comparison with worked examples, read dollar-cost averaging vs lump sum. For crypto, see is buying $100 of bitcoin a month worth it.
Fees matter on small purchases
A fixed fee or a high percentage fee takes a bigger bite out of small, frequent purchases. A 2% fee on every $100 purchase means the price has to rise 2% just to break even on each buy. See maker vs taker fees for how to lower crypto trading costs.
How to use a dollar-cost averaging calculator to make better decisions
A dollar-cost averaging calculator is most useful when you look back at real purchases. Enter the prices from your last six or twelve buys and compare your average cost with today’s price. If your average cost is well below the current price, regular buying has worked in your favour. If it’s above, you’re sitting on a paper loss, which is normal during a falling market and often temporary for long-term investors.
You can also use it to test “what if” scenarios before you start. Try a steady rise, a fall followed by a recovery, and a long sideways market. You’ll see that regular buying helps most when prices dip and recover, and that a lump sum usually wins when prices climb steadily.
Keep an eye on costs too. Fees on small, frequent purchases can noticeably raise your average cost, so check the fee per purchase on your platform. The Securities and Exchange Commission’s investor site explains how fees affect your returns.
Frequently asked questions
What is dollar-cost averaging?
Investing a fixed amount at regular intervals, such as monthly, regardless of the price. It spreads your purchases over time and removes the pressure to time the market.
Does dollar-cost averaging guarantee a profit?
No. It can lower your average cost compared with buying at a single high price, but if prices fall and stay down, you can still lose money.
Is dollar-cost averaging better than investing a lump sum?
Not always. Historically, lump sums have often done better when markets rise, but regular investing suits most people who invest from their monthly pay, and can reduce the risk of investing everything just before a fall.
Is my data saved?
No. The calculator runs in your browser, and nothing you enter is stored.
Related tools
This calculator is for education only and is not investment advice. Past prices don't predict future returns. Results ignore taxes.