Dollar-Cost Averaging Calculator: method, checked example and practical limits
Calculate units accumulated and average cost from a list of periodic purchase prices. Average cost is total committed money divided by accumulated units under the defined fee convention.
Inputs used by this calculator
Dollar-Cost Averaging Calculator uses the fields below. The starting values reproduce the page example; replace them with values from the same units and time period before using the result.
| Input | Starting example | Accepted value | How it is used |
|---|---|---|---|
| Purchase prices, separated by commas | 100, 90, 80, 110 | Text or a list in the format shown | Supplies the purchase prices, separated by commas quantity used by the published equation or result breakdown. |
| Amount invested each purchase | 250 | 0.01 to 1000000000000000 | Supplies the amount invested each purchase quantity used by the published equation or result breakdown. |
| Fee per purchase | 0 | 0 to 1000000000000 | Supplies the fee per purchase quantity used by the published equation or result breakdown. |
| Current asset price | 105 | 0 to 1000000000000000 | Supplies the current asset price quantity used by the published equation or result breakdown. |
Inputs and measurement conventions
The quantities used on this page are Purchase prices, separated by commas, Amount invested each purchase, Fee per purchase, Current asset price. Start with values for the same situation and read the units attached to each field. The field reference below shows supported choices and numerical limits.
Equal cash contributions do not buy equal units. Returns, taxes and sale proceeds require additional information beyond the purchase history.
Method and equation
Deduct the fee from each periodic investment, divide by that period's purchase price and add acquired units across the entered sequence.
Dollar-Cost Averaging Calculator uses the following stated relationship: units per purchase = (periodic amount − fee) ÷ purchase price; average cost = total invested ÷ total units. Its assumptions determine which question the answer can resolve.
units per purchase = (periodic amount − fee) ÷ purchase price; average cost = total invested ÷ total unitsWorked calculation with the starting values
Purchase prices, separated by commas: 100, 90, 80, 110; Amount invested each purchase: 250; Fee per purchase: 0; Current asset price: 105. These starting values give 93.67238321 average cost per unit. The calculation breakdown is Purchases: 4; Total invested: 1,000; Units accumulated: 10.67550505; Current value: 1,120.92803.
Four equal $250 purchases at different prices accumulate more units when prices are lower.
Reading the answer
Average cost is total committed money divided by accumulated units under the defined fee convention.
Purchases: 4; Total invested: 1,000; Units accumulated: 10.67550505; Current value: 1,120.92803. These intermediate quantities make the stated Dollar-Cost Averaging Calculator model inspectable; they should be read together with the main answer rather than treated as independent guarantees.
Common errors and model boundaries
Equal cash contributions do not buy equal units. Returns, taxes and sale proceeds require additional information beyond the purchase history.
This historical arithmetic does not predict prices, taxes, spreads, custody risk or investment suitability.
Independent verification and next decision
No. It changes purchase timing and average cost but cannot prevent the asset's market value from declining.
For the Dollar-Cost Averaging Calculator method, compare units per purchase = (periodic amount − fee) ÷ purchase price; average cost = total invested ÷ total units with the starting inputs and the calculation table. The linked Investor.gov: investing basics and FINRA: investing references identify the relevant definitions, conventions or domain limitations. Retain intermediate precision when comparing a manually worked answer.
Dollar-Cost Averaging Calculator worked-example ledger
| Quantity | Example value | Role |
|---|---|---|
| Purchase prices, separated by commas | 100, 90, 80, 110 | Entered assumption |
| Amount invested each purchase | 250 | Entered assumption |
| Fee per purchase | 0 | Entered assumption |
| Current asset price | 105 | Entered assumption |
| Main answer | 93.67238321 average cost per unit | Calculated from the starting inputs |
| Purchases | 4 | Intermediate or contextual output |
| Total invested | 1,000 | Intermediate or contextual output |
| Units accumulated | 10.67550505 | Intermediate or contextual output |
| Current value | 1,120.92803 | Intermediate or contextual output |
| Unrealized change | 120.9280303 | Intermediate or contextual output |
Frequently asked questions
Does dollar-cost averaging guarantee a gain?
No. It changes purchase timing and average cost but cannot prevent the asset's market value from declining.
Which relationship does the Dollar-Cost Averaging Calculator use?
Deduct the fee from each periodic investment, divide by that period's purchase price and add acquired units across the entered sequence. The displayed relationship is units per purchase = (periodic amount − fee) ÷ purchase price; average cost = total invested ÷ total units.
What do the starting values produce in the Dollar-Cost Averaging Calculator?
Purchase prices, separated by commas: 100, 90, 80, 110; Amount invested each purchase: 250; Fee per purchase: 0; Current asset price: 105. These starting values give 93.67238321 average cost per unit. The calculation breakdown is Purchases: 4; Total invested: 1,000; Units accumulated: 10.67550505; Current value: 1,120.92803.
How should I interpret this Dollar-Cost Averaging Calculator answer?
Average cost is total committed money divided by accumulated units under the defined fee convention.
Which input mistake most affects the Dollar-Cost Averaging Calculator?
Equal cash contributions do not buy equal units. Returns, taxes and sale proceeds require additional information beyond the purchase history.
What is outside this Dollar-Cost Averaging Calculator model?
This historical arithmetic does not predict prices, taxes, spreads, custody risk or investment suitability.
What to keep in mind
This historical arithmetic does not predict prices, taxes, spreads, custody risk or investment suitability.
Results are rounded for display in US format, with money in dollars and cents; CSV exports keep full calculation precision. This is a calculation summary, not an official certificate.