Compounding Frequency
Fréquence de capitalisation in French
Quick definition
Compounding frequency is how often earned interest is added to your balance so it starts earning interest itself. At the same posted rate, more frequent compounding produces a higher return.
Why the same rate pays different amounts
A posted interest rate is almost always a nominal annual rate, and on its own it does not tell you what you will earn. The missing piece is how often the interest is credited. Each time it is credited, it joins the balance and starts earning compound interest of its own.
The formula is the same in every case: the final amount equals the principal multiplied by (1 + r/n) raised to the power of n times t, where r is the nominal annual rate, n is the number of compounding periods per year, and t is the number of years.
The common frequencies
Canadian products use a small handful of frequencies, and which one applies is usually buried in the product details rather than shown beside the rate.
- Daily (n = 365): most high-interest savings accounts accrue daily and post monthly.
- Monthly (n = 12): many lines of credit and some GICs.
- Quarterly (n = 4): some savings products and corporate deposits.
- Semi-annually (n = 2): the legally required convention for Canadian fixed-rate mortgages.
- Annually (n = 1): the default for most GICs and term deposits.
- None (simple interest): interest accrues on the original principal only and never compounds.
How much difference it actually makes
Less than most people expect at low rates, and more than they expect over long periods. On $10,000 at 5% for one year, annual compounding pays $500 and daily compounding pays $512.67, a gap of under $13.
Stretch the same comparison to ten years and annual compounding produces $16,289 while daily produces $16,487. The gap has grown to $198, and it keeps widening because the difference itself compounds.
The practical rule: frequency matters more as the rate rises and as the horizon lengthens. On a two-year GIC it is a rounding detail. On a thirty-year projection it is real money.
Comparing products properly
The only fair way to compare two rates with different compounding is the effective annual rate, which converts any nominal rate and frequency into the single annual rate that would produce the same result. A savings account advertising 4.00% compounded daily has an effective annual rate of 4.08%, so it beats a GIC at 4.05% compounded annually despite the lower headline number.
This is the whole reason the effective rate exists. See APR vs effective annual rate for how the same idea applies on the borrowing side, where a nominal rate quoted monthly understates what the debt actually costs.
The Canadian mortgage exception
Canadian fixed-rate mortgages are required by the Interest Act to be compounded no more than semi-annually, not in advance, regardless of how often you pay. This is a genuine consumer protection and it is the main reason Canadian and American mortgage payments differ at identical posted rates: US mortgages compound monthly.
Variable-rate mortgages and lines of credit are not covered by that rule and typically compound monthly. See semi-annual compounding for the detail.
In Canada
Canadian high-interest savings accounts almost universally accrue interest daily and pay it monthly, which is why the effective rate on a HISA slightly exceeds its posted rate.
Most Canadian GICs compound annually by default, though many issuers offer monthly-compounding or annual-payout versions of the same term at slightly different rates. The version matters as much as the rate.
Credit cards compound daily, which is the same mechanism working against you. A balance carried at 19.99% has an effective annual rate closer to 22%.
Worked example
Nadia compares two five-year GICs, both quoted at 4.00%. The first compounds annually, the second monthly. On $25,000 the annual version matures at $30,416 and the monthly version at $30,525, a difference of $109. She then finds a third GIC at 3.95% compounded daily; its effective annual rate is 4.03%, which still leaves it behind the 4.00% monthly option. The effective rate is the only number that let her rank all three.
Reviewed by Alexandre Bernier, CFP®, CIM®, PFP®·Updated September 2026