DCA Calculator

1. Enter the fixed amount per purchase, for example 100 each week or month.
2. List the price at each purchase, oldest first.
3. Optionally enter todays current price; otherwise the last purchase price is used.
4. Read your value, average cost, profit and the lump-sum comparison.

Dollar cost averaging is an investing habit: you buy a fixed money amount of an asset on a regular schedule, whatever its price. When the price is low your fixed amount buys more units, and when it is high it buys fewer. Over time your average cost per unit smooths out the swings.

It is popular with Bitcoin and other cryptocurrencies because their prices move sharply, and with index funds through automatic monthly contributions. DCA removes the pressure of trying to time the market and turns investing into a routine. It does not guarantee a profit or protect against a long decline.

If you want to see a single past purchase instead of a series, the crypto what-if calculator models one buy at one date.

It adds up the units each purchase bought, then values them at the current price.

With a fixed amount A and prices P_i, the average cost is n / sum(1/P_i), the harmonic mean of the prices. The harmonic mean is always at or below the ordinary average, which is the mathematical reason DCA lowers your cost basis in a volatile market.

1. Divide the amount by each purchase price to get units bought that time.
2. Add the units and multiply the amount by the number of purchases to get total invested.
3. Divide total invested by units for the average cost.
4. Multiply units by the current price for value, and compare with a lump sum bought at the first price.

Suppose you buy 100 of Bitcoin a month for six months while the price moves 30,000, 25,000, 20,000, 28,000, 35,000 and 40,000. You invest 600 and collect about 0.021262 BTC.

Your average cost is about 28,219, below the simple average price of about 29,667, because the dip months bought more coin. At 40,000 your holding is worth about 850, a profit of about 250 or 41.7 percent. Putting the whole 600 in at the first price of 30,000 would be worth only 800, so DCA came out ahead by about 50.

In a steady uptrend it flips. Buying 100 at 40,000, 45,000, 50,000, 55,000 and 60,000 gives an average cost of about 48,986 and a value of about 612, while a lump sum at 40,000 would be worth 750.

Studies of stock markets have found a lump sum beats DCA roughly two thirds of the time, simply because markets rise more often than they fall. DCA wins on regret: it avoids putting everything in at a peak. For money you earn gradually, such as salary, DCA is the natural default anyway.

Volatility

The bigger the price swings, the further your average cost falls below the average price.

Price Trend

A falling-then-rising path flatters DCA; a steady climb favours a lump sum.

Purchase Frequency

Weekly buys average more finely than monthly ones, but add more transaction fees.

Fees

Flat fees on small buys can eat a noticeable share of each purchase on some exchanges.

Time Horizon

DCA is a long-term habit; over a few months the result mostly reflects luck in the price path.

Checking a Recurring Buy

See your true average cost and profit on a weekly or monthly crypto or ETF purchase.

Back-testing a Plan

Paste historical prices to see how a DCA plan would have done.

Deciding Lump Sum or Spread

Compare the two approaches for a windfall over a past price path.

Setting a Break-even

Your average cost is the price you need to reach to be back in profit.

1. Stopping When Prices Fall

Pausing in a dip removes exactly the cheap buys that make DCA work.

2. Ignoring Fees

High fixed fees on small purchases can erase the benefit.

3. Confusing Average Price with Average Cost

Your cost is the harmonic mean, not the simple mean of prices.

4. Treating DCA as Risk-free

If an asset declines for good, averaging down only adds to losses.

5. Forgetting Tax Records

Each buy is a separate tax lot, which matters when you sell.

It is investing a fixed amount at regular intervals regardless of price, so you buy more units when prices are low and fewer when they are high.

Divide the total amount invested by the total units bought. With equal purchase amounts this equals the harmonic mean of the purchase prices.

Historically a lump sum wins more often in rising markets, but DCA does better when prices dip after you start and reduces the risk of buying at a peak.

It is a popular approach for Bitcoin because its price is volatile. It smooths your entry price but does not guarantee a profit.

Weekly or monthly are common. More frequent buys average more finely but can cost more in fees.

Fixed amounts buy more units at low prices, pulling your cost below the simple average of the prices.

Yes. The math is the same for any asset bought with a fixed amount on a schedule.

No. Subtract any fee from the amount per purchase to approximate its effect.

No. The calculation runs in your browser, and nothing you enter is sent anywhere unless you Save a result, which stays on this device only.

• Dollar cost averaging (Wikipedia).
• Dollar-cost averaging explained (Investopedia).
• Harmonic mean (Wikipedia).