Work it out
The starting values are an illustration, not a suggested trade or allocation.
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Worked example
Fifteen units cost 1,550 before fees, 1,552 including entry fees, and require 1,555 of sale proceeds to cover the additional 3-unit exit cost.
Use one asset, one currency, and units still held
Each row represents a purchase lot that remains in the position: quantity, price, total entry fee. Omit headers, use decimal points, and separate columns with commas or tabs. The calculator accepts up to 200 rows.
All lots must represent the same unit of the same asset in one currency. Do not mix stock shares, derivative contracts, short-sale lots, or already-sold units. The tool does not reconstruct sales, stock splits, transfers, or tax lots.
Weight the price by quantity
Total units = sum of each lot’s quantity. Total execution value = sum of quantity × price. Weighted average entry = total execution value / total units.
An ordinary average of the row prices is correct only when all quantities are equal. A one-unit purchase should not affect the average as much as a one-hundred-unit purchase.
Keep fees separate from the execution price
Entry cash cost per unit = (total execution value + all entry fees) / total units. This differs from the quantity-weighted execution price because fees are cash costs, not changes to the quoted fill price.
Break-even exit = (total execution value + entry fees + estimated total exit costs) / total units. It assumes a single sale price for all listed units and fixed exit costs equal to the amount entered.
Check the two-lot example
The default purchases are 10 units at 100 and 5 units at 110. Execution value is 1,000 + 550 = 1,550 across 15 units. The weighted entry is 103.3333, while the unweighted average of 100 and 110 would incorrectly be 105.
Entry fees of 1 per lot bring entry cash cost to 1,552, or 103.4667 per unit. Add total exit costs of 3 and the break-even exit becomes 1,555 / 15 = 103.6667.
Distinguish a better average from a better position
Buying more at a lower price can reduce the average entry while increasing the total cash committed and the amount exposed to further price moves. The arithmetic does not establish that an additional purchase improves the decision.
Compare total units and total entry cash cost before and after any hypothetical lot. The tool describes the combined position; it does not recommend averaging down or adding leverage.
Reconcile with a statement
A broker may show average execution price, tax basis, or a figure adjusted for charges and corporate actions. Those are not always the same number. Match the definition before treating a difference as an error.
For a partially sold position, use accurate remaining lots rather than subtracting sale proceeds from the original purchase cost. Tax accounting is outside this calculator.
What this tool does not calculate
- Long purchase lots only, with no contract multiplier or currency conversion.
- All entered units are assumed still held.
- The break-even price uses a fixed total exit-cost estimate; it is not a tax calculation.
Common questions
Why not average the purchase prices directly?
Different quantities carry different weights. Multiply each price by its quantity, add those values, and divide by the total quantity.
Is the result my tax cost basis?
Not necessarily. Tax-lot elections, sales, adjustments, and local rules can produce another figure. This is a cash-cost model for the long units entered.
Can I include fractional units?
Yes. Quantities may be positive decimals. All rows must still refer to the same asset and unit.
Does a lower average entry make adding to a loss safer?
The calculator cannot establish that. Adding units can reduce the average entry while increasing total exposure and potential loss.
Sources & method
An original calculation tool built with AI assistance. Its method and limits are documented here, and calculation examples are checked with automated tests.
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About Read The Setup