Adjusted cost base (ACB) is the number that determines your taxable capital gain when you sell a Canadian investment. Calculating it correctly is your legal obligation — not your broker’s.
Add purchases, sales, DRIP reinvestments and return-of-capital adjustments to see how each transaction changes your running adjusted cost base.
This free calculator demonstrates one pooled security in Canadian dollars. It handles buys, sales, DRIP reinvestments, and return-of-capital adjustments. For multiple brokerages, USD trades, additional ETF adjustments, and saved transaction history, use myCostBase.
What adjusted cost base means for Canadian investors
Adjusted cost base is the average cost per share of a security, calculated across all taxable accounts you hold for that security, and adjusted over time for events that change your cost. When you sell, your capital gain equals:
Proceeds of disposition − Adjusted cost base − Selling commissions = Capital gain or loss
The “adjusted” part is what makes this calculation more complex than a simple average: return-of-capital distributions from ETFs reduce your ACB; DRIP reinvestments add to it; stock splits change the per-share figure; and transfers between brokerages must carry the original cost forward without a reset.
CRA’s rule is the weighted average pooling method: every share of the same security held in any taxable account by the same investor is one pool. If you hold XEQT at Wealthsimple and Questrade, you don’t have two ACBs — you have one pooled ACB across both positions.
What transactions affect adjusted cost base
A complete ACB calculator must handle all of the following:
| Transaction | Effect on ACB |
|---|---|
| Purchase (buy) | Increases total ACB; recalculates ACB per share |
| Sale (full or partial) | No change to ACB per share; reduces share count only |
| DRIP reinvestment | Increases total ACB and share count (treated as a purchase at distribution price) |
| Return of capital (ROC) | Reduces total ACB; lowers ACB per share |
| Phantom income / reinvested gains | Increases total ACB (you paid tax on this income) |
| Stock split | Doubles shares, halves ACB per share; total ACB unchanged |
| Stock consolidation | Reduces shares, increases ACB per share; total ACB unchanged |
| Broker transfer (taxable to taxable) | ACB carries through at original cost — no reset at market value |
| Superficial loss denial | Denied loss added to the ACB of the repurchased shares |
Why simple ACB calculators fall short
A one-transaction ACB calculator can compute the gain on a single buy-and-sell scenario. It cannot:
- Pool across multiple brokerage accounts
- Apply annual ETF distribution adjustments (ROC, phantom income)
- Handle years of DRIP reinvestments across dozens of dates
- Convert USD trades at Bank of Canada daily rates per transaction
- Carry ACB through broker transfers at original cost
- Reconcile against T5008 Box 20 at year end
For the single-security, single-account investor with no ETF distributions, a simple calculator or spreadsheet is adequate. For most Canadian investors with diversified taxable portfolios — particularly those holding ETFs across multiple accounts or trading USD-denominated securities — a running ledger is the appropriate tool.
ACB calculation example
Two purchases and a partial sale of a Canadian stock:
January 2022: Buy 100 shares of RY.TO at $132.00. Commission: $9.95.
- Total ACB: $13,209.95
- ACB per share: $132.10
June 2022: Buy 50 more shares at $128.00. Commission: $9.95.
- New total ACB: $13,209.95 + (50 × $128.00) + $9.95 = $19,619.90
- Total shares: 150
- ACB per share: $130.80
March 2024: Sell 60 shares at $140.00. Commission: $9.95.
- Proceeds: (60 × $140.00) − $9.95 = $8,390.05
- ACB deducted: 60 × $130.80 = $7,848.00
- Capital gain: $542.05
- Remaining: 90 shares at ACB per share of $130.80
The ACB per share does not change when you sell a partial position. Only the share count decreases.
Average cost base calculator vs. ACB ledger
“Adjusted cost base” and “average cost base” refer to the same calculation method — both use the weighted average pooling approach required by CRA. The term “average cost base calculator” is sometimes used interchangeably with ACB calculator. The calculation is identical; the terminology differs by preference.
For a complete step-by-step worked example including stocks, ETFs, USD trades, and partial sales, see How to Calculate Adjusted Cost Base in Canada.
What this free calculator does and does not cover
The calculator above is designed for one security in Canadian dollars. It shows the running ACB after each buy, sell, DRIP, and return-of-capital adjustment, including the realized gain or loss on sale transactions.
It does not yet model phantom income distributions, stock splits, transfers, portfolio-wide record keeping across multiple brokerages, USD FX conversion workflows, or ETF adjustment management across multiple years. When return of capital exceeds the remaining ACB, the calculator shows the excess as a capital gain; verify uncommon or complex situations before filing. For those workflows, use myCostBase.
From this calculator to a full ACB ledger
The calculation above is the same one myCostBase runs for every security you hold — it just stops being manual. Instead of re-entering one security at a time, you enter or import transactions once and the ledger stays current automatically:
- Every account pools into the same weighted-average figure this calculator produces for one security
- ETF return-of-capital and phantom income adjustments apply themselves as provider data arrives
- USD trades convert at the Bank of Canada rate for their own transaction date, not a rate you look up once and reuse
- T5008 Box 20 is checked against your ledger automatically at year-end instead of by hand
- Every adjustment stays in an audit trail you can hand to a tax preparer
The free plan supports unlimited manual transaction entry for up to 2 taxpayers. Start with the security you just calculated above, then add the rest of your portfolio when you’re ready.
For investors currently using a spreadsheet, see Adjusted Cost Base Spreadsheet for Canadian Investors for a comparison of when each approach is appropriate.