The effective annual rate (E.A.) shows what is actually paid or earned in a year, including the compounding of interest. The nominal rate is a reference annual rate that is split into periods (month, quarter); to compare it with others it must be converted to an effective annual rate.
The three types of rate
- Effective annual (E.A.): what it really costs or earns in a year.
- Nominal, paid in arrears: a reference annual rate; interest is paid at the end of each period.
- Nominal, paid in advance: a reference annual rate; interest is paid at the start of each period, so it costs more for the same number.
Example: the same figure, three different costs
| Agreed rate | Equivalent to (E.A.) |
|---|---|
| 24% effective annual | 24.00 % |
| 24% nominal monthly, paid in arrears | 26.82 % |
| 24% nominal monthly, in advance | 27.43 % |
All three say “24%”, but the nominal monthly rate paid in arrears costs 26.82% a year and the one paid in advance, 27.43%. Comparing without converting leads to a poor choice.
The formulas
Nominal in advance → E.A.: (1 − j/m)^−m − 1
E.A. → period rate: i = (1 + E.A.)^(1/m) − 1
j is the nominal annual rate and m the number of periods in the year (12 monthly, 6 two-month, 4 quarterly, 2 semiannual).
Why it matters
To compare loans, CDTs (term deposits) or savings accounts, all rates must be brought to the same basis. The effective annual rate is the standard way. It is also the basis used to compare a rate against the usury rate.
BankIA’s rate converter does the calculation and shows all the equivalents, with the formulas in plain view.
Last updated: October 9, 2026. Written by the BankIA (jsadsAI) team. Educational content: it does not constitute financial or legal advice.
Frequently asked questions
Which is better, a nominal rate or an effective rate?
They are neither better nor worse: they are ways of expressing the same thing. To compare, always use the effective annual rate.
What do “month in arrears” and “month in advance” mean?
In arrears: interest is paid at the end of the month. In advance: it is paid at the start, so for the same nominal rate the effective rate is higher.
Is 2% monthly the same as 24% annually?
Not exactly. 2% effective monthly equals 26.82% effective annual, because interest is compounded. The 24% comes from adding 2% twelve times, without compounding.
Keep exploring
Rate converter
Convert an effective annual rate to a nominal rate paid in arrears or in advance (monthly, quarterly, semiannual) and back, with the formulas shown.
Open →Usury rate in Colombia
The usury rate is the legal interest cap in Colombia: 1.5 times the current bank interest rate. What it is, who certifies it and where to see the current one.
Open →Loan simulator
Calculate the installment, interest and amortization schedule of a fixed-installment loan and compare your rate with the usury rate in Colombia.
Open →Put it into practice with your own data.
Request a demo and we will show you the platform running with your name and your rules.