adjusted cost base calculator

Use this free adjusted cost base (ACB) calculator to track buys, sells, DRIPs, and return of capital events in one place. It estimates your current ACB, ACB per share, and realized capital gains/losses from sales.

Opening Shares (optional)

Use if you already owned shares before the transactions below.

Opening Total ACB (CAD)

Total cost base attached to opening shares.

Transaction Ledger

For Buy/Sell entries, enter total trade amount (not price per share). Fees are optional and deducted from proceeds for sells, added to cost for buys.

Date	Type	Shares	Amount (CAD)	Fees (CAD)	Action

Educational tool only. Tax reporting rules vary by jurisdiction and account type. Confirm with your tax professional.

What is adjusted cost base (ACB)?

Adjusted cost base is the tax cost of an investment position after accounting for changes over time. In plain language, it is what your shares “really cost” after purchases, commissions, reinvested distributions, and return of capital adjustments. When you sell, your gain or loss is based on proceeds minus the portion of ACB allocated to the shares sold.

For many investors in taxable accounts, good ACB tracking is essential for accurate capital gains reporting. If your records are incomplete, you can overpay tax or create avoidable filing stress.

How this ACB calculator works

Supported transaction types

Buy: increases shares and increases ACB by amount + fees.
Sell: realizes gain/loss using average ACB per share at the time of sale.
DRIP (reinvested distribution): increases shares and increases ACB by the reinvested amount.
ROC (return of capital): reduces ACB (does not change shares).

Core formula

At any point in time:

ACB per share = Total ACB / Total shares held
ACB removed on sale = Shares sold × ACB per share
Capital gain/loss = Net sale proceeds − ACB removed

Step-by-step usage guide

Enter opening shares and opening total ACB if you already owned units.
Add each transaction in chronological order.
For buys and sells, use total dollar amount of the trade.
Include commissions/fees where applicable.
Click Calculate ACB to view ending ACB and realized gains/losses.

Practical example

Suppose you buy 100 shares for $2,500 plus $10 commission. Your ACB becomes $2,510. Later you buy 50 more for $1,400 plus $10, bringing ACB to $3,920 over 150 shares. Your average ACB per share is now $26.13.

If you then sell 80 shares for $2,400 with a $10 fee, net proceeds are $2,390. ACB removed is 80 × $26.13 = $2,090.40 (approx). Realized capital gain is about $299.60. Remaining shares continue with the remaining ACB.

Common ACB mistakes to avoid

Ignoring commissions: trading costs matter for tax basis.
Forgetting DRIPs: reinvested distributions increase ACB.
Missing ROC adjustments: ROC lowers your basis and affects future gains.
Mixing registered and non-registered accounts: ACB tracking is generally for taxable accounts.
Out-of-order entries: chronology is critical when calculating sale gains.

Final thoughts

An adjusted cost base calculator is one of the most practical tools for long-term investors. With consistent tracking, tax season becomes easier, audit risk is lower, and gain/loss estimates are much more reliable. Save your trade confirmations, update your ledger regularly, and review unusual corporate actions carefully.