Business and Financial Tools
DCA and Average Cost per Unit Calculator
Calculate directly from prices you enter when equal cash purchases acquire a different number of shares or fund units each period.
Private scenario calculator
DCA and Average Cost Calculator
Change any assumption to recalculate instantly. Values stay in this browser and are not saved.
Cost basis
Quick answer
How is the average cost of DCA purchases calculated?
Units for each period equal the fixed investment divided by that period's price. Average cost is total invested divided by total units, not the arithmetic mean of purchase prices.
How to use this tool
- Enter purchase prices on separate lines or separated by commas.
- Enter the equal amount invested each period and current unit price.
- Review units, average cost, current value, and unrealized gain or loss.
How the calculation works
The calculator divides the equal periodic amount by every positive price, then adds the units. Average cost = total invested ÷ total units, current value = total units × current price, and gain or loss = current value − total invested. Fees, taxes, and distributions are excluded.
Examples
| Example | Input | Expected result |
|---|---|---|
| Two purchases | |
150 units, average cost THB 13.333333, current value THB 3,000, and gain THB 1,000 |
| Same price each period | |
300 units and average cost THB 10 |
Limitations
- The periodic cash amount must be equal; differing purchases need a transaction-level calculator.
- Brokerage, VAT, exchange fees, taxes, dividends, and corporate actions are excluded.
- Unrealized gain or loss is not a buy, hold, or sell recommendation.
Frequently asked questions
Why is average cost different from the mean purchase price?
Equal cash buys more units at a low price and fewer at a high price, so unit quantities must weight the calculation.
Does DCA guarantee a profit?
No. It spreads purchase timing, but the current price can remain below average cost.
Does this tool fetch market prices?
No. Enter prices from records or a source you have verified; the entries are not stored on the server.
References
- Thai SEC — DCA investment strategy Verified 2026-08-03
- FINRA — Dollar-Cost Averaging Verified 2026-08-03
Content and calculation method last reviewed: