The weighted average formula
New average = (current quantity × its average + new quantity × its price) ÷ total quantity. This is the famous "dollar-cost averaging" (DCA) strategy: buying regularly regardless of price swings produces a less volatile average cost than trying to "time the market."
Buying below your current average lowers the average ("averaging down"), while buying above it raises it — the calculator shows the change as a percentage instantly.
FAQ
Is lowering the average always a good decision?
Not necessarily — lowering the average by buying more of an asset whose price keeps falling ("trying to catch a falling knife") can increase your loss if the decline continues. The decision depends on your analysis of the asset itself, not just the math.
Does the calculator include commissions?
No, this is a pure average-price calculator. To calculate net profit including commissions and taxes, use the "Stock Trade Profit" calculator.
Source
Standard dollar-cost averaging (weighted average) formula.
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Last updated: July 2026
This calculator is a general mathematical tool and not investment advice. Read the full disclaimer.