Tool

Adjusted cost base calculator

One security, in order. Each row shows what the adjusted cost base became after that transaction, and each sale shows the gain or loss it realized. It runs in your browser. Nothing you type is sent anywhere, and nothing is saved when you leave.

Transactions in one security, in the order they happened. Each row shows the adjusted cost base after that transaction.
Type	Date	Quantity	Price	Commission	ACB / unit after	Gain or loss
Transaction type, row 1	Date, row 1	Quantity, row 1	Price per unit, row 1	Commission, row 1	$42.60	—
Transaction type, row 2	Date, row 2	Quantity, row 2	Price per unit, row 2	Commission, row 2	$48.80	—
Transaction type, row 3	Date, row 3	Quantity, row 3	Price per unit, row 3	Commission, row 3	$48.80	$557.09

Units held: 90
Total ACB: $4,391.94
ACB per unit: $48.80
Realized gain or loss: $557.09

How it calculates

Canadian non-registered accounts use the average-cost method, not first-in-first-out. Every buy adds its cost and its commission to one pool. Every sale takes the pool divided by units held before that sale as its cost per unit, and subtracts its commission from the proceeds. Commission works against you in both directions, which is correct, and is the part hand arithmetic usually drops.

Rows are applied in the order shown, not sorted by the date you type. The date field is a label for your own reference. Reorder by editing, or enter them chronologically.

What this does not handle

Superficial losses. If you sell at a loss and you or an affiliated person buy the same security within 30 days either side of the sale, the CRA denies that loss and adds it to the cost base of the repurchased shares. This calculator does not apply that rule, so a loss shown here may not be a loss you can claim. It is excluded deliberately rather than overlooked: Luum’s own Tax Centre leaves it to you for the same reason, and a tool that guessed at it would produce a confident number you might file against.
More than one security, and more than one currency. ACB is tracked per security, and a foreign-currency transaction converts at its own trade-date rate, and one rate applied at the end gives the wrong answer.
Short positions, splits, return of capital, and reinvested distributions. Each changes the pool in its own way. A DRIP in particular is a purchase and raises your ACB, which is the most commonly missed adjustment of the lot.
Registered accounts. ACB does not apply inside a TFSA, RRSP, FHSA or RESP. If the account is registered, none of this is relevant to your return.

Educational only, and accurate to what you enter. This is not tax advice and it does not file anything. For the concepts behind it, read adjusted cost base explained. To check the figure you reach here against box 20 on your T5008 slips, use the T5008 and cost base checker. For how Luum computes the same figure across your real accounts, see ACB tracking.