What is dollar-cost averaging?

Investing a fixed amount at regular intervals regardless of price. The fixed amount automatically buys more units when prices are low and fewer when high.

Why is my average cost below the average price?

Because a fixed dollar amount buys more units at low prices, your per-unit cost is the harmonic mean of the prices — mathematically at or below the simple average.

Is DCA better than lump-sum investing?

Historically lump sum wins more often in rising markets (more time invested), while DCA reduces timing risk and regret in volatile ones. It is primarily a risk-management choice.

How do I use this with my own history?

Enter your recurring buy amount and the price at each purchase, in order. The last price is used to value the position — replace it with today's price for a current mark.

Does this work for stocks and ETFs?

Yes — the maths is asset-agnostic. Any recurring fixed-amount purchase plan (shares, ETFs, crypto) averages the same way.

Fees are excluded; subtract per-order costs from each buy amount (or add them to your cost basis) for a net-of-fees view.

Crypto

DCA Calculator (Dollar-Cost Averaging)

Calculate dollar-cost averaging results from a fixed buy amount and a series of prices — units accumulated, true average cost and profit or loss.

Dollar-cost averaging (DCA) is investing a fixed amount at regular intervals, which buys more units at low prices and makes the average cost the harmonic mean of the purchase prices.

Average cost per unit

$38.46

Units accumulated: 13
Total invested: $500.00
Average market price: $41.00
Current value: $650.00
P&L: $150.00
Return: +30%

Fees excluded — subtract per-order costs from the buy amount for a net view.

Worked example

An investor buys $100 of BTC each month for five months at prices of $50, $40, $25, $40 and $50 (in thousands).

Units bought: 2 + 2.5 + 4 + 2.5 + 2 = 13 units
Total invested: $100 × 5 = $500
Average cost: $500 ÷ 13 = $38.46
Average market price: $41.00
Value at final price: 13 × $50 = $650 (+30%)

Fixed buys accumulate more units at the $25 low, so the average cost ($38.46) beats the average price ($41). The position ends 30% up even though the final price equals the first.

How this is calculated

Each period the fixed amount buys whatever it can at that price:

units(t) = amount ÷ price(t)
averageCost = totalInvested ÷ totalUnits

Because low prices buy more units, the average cost is the harmonic mean of the purchase prices — mathematically at or below the simple average. The gap between the two is exactly what volatility contributed to your cost basis.

The position is valued at the last price in the series: value = totalUnits × lastPrice. Append today's price to mark the position to market.

When to use this calculator

Use this to audit a recurring-buy plan with your real purchase prices: total units accumulated, the true average cost, and profit at today's price. It replaces spreadsheet bookkeeping for the most common retail strategy in crypto.

It is also a planning tool: run hypothetical price paths (a grind down and recovery, a steady rally) to see how the average cost behaves — the volatile path often ends with a better cost basis than the smooth one, which is DCA's whole argument.

Use the average-cost-versus-average-price gap as the strategy's scorecard: the wider your buys' harmonic-mean advantage, the more the volatility worked for you.

Common mistakes

Judging DCA over a period that only trended one way — its edge over lump-sum shows in volatile, mean-reverting stretches, not steady rallies.
Stopping the plan during drawdowns, which removes exactly the cheap buys that make the average cost work.
Ignoring per-order fees: small frequent buys on a high-fee venue can cost more than the averaging saves.

Frequently asked questions

What is dollar-cost averaging?: Investing a fixed amount at regular intervals regardless of price. The fixed amount automatically buys more units when prices are low and fewer when high.
Why is my average cost below the average price?: Because a fixed dollar amount buys more units at low prices, your per-unit cost is the harmonic mean of the prices — mathematically at or below the simple average.
Is DCA better than lump-sum investing?: Historically lump sum wins more often in rising markets (more time invested), while DCA reduces timing risk and regret in volatile ones. It is primarily a risk-management choice.
How do I use this with my own history?: Enter your recurring buy amount and the price at each purchase, in order. The last price is used to value the position — replace it with today's price for a current mark.
Does this work for stocks and ETFs?: Yes — the maths is asset-agnostic. Any recurring fixed-amount purchase plan (shares, ETFs, crypto) averages the same way.
What about fees?: Fees are excluded; subtract per-order costs from each buy amount (or add them to your cost basis) for a net-of-fees view.