ToolnozaWeighted average cost formula
New average cost = (existing quantity × existing unit cost + additional quantity × new price + new fees) ÷ total quantity. Total quantity equals existing plus additional units. Include past fees in the existing unit cost so they are not omitted or counted twice.
Worked example
Suppose you own 10 units at 100 each and buy 10 more at 80, with no new fees. Total cost is 10 × 100 + 10 × 80 = 1,800; total units are 20; average cost is 1,800 ÷ 20 = 90 per unit.
Include fees and use consistent inputs
Add new purchase fees once to the total cost. Enter prices and fees in the same currency and use units that match the asset. If the additional quantity is zero, there is no new purchase to average. If total quantity is zero, an average price is undefined.
What averaging down does not tell you
A lower average cost does not make an asset safer or guarantee a recovery. The result is an arithmetic cost basis estimate; it excludes taxes, currency conversion and platform-specific accounting rules unless entered. It is not a recommendation to buy or sell.
Frequently asked questions
Does averaging down reduce the average when I buy below my cost? Yes, when the added units cost less than the existing average. Does it change the market price? No, it changes only your calculated average cost. Are fees included? Enter new fees in the fee field and include old fees in the existing unit cost.