48/3335–8FE Reference Handbook 10.4 · Engineering Economics · Effective rates

Handbook formula

Effective Interest Rate

r is the nominal annual rate, m the number of compounding periods per year. ie is the effective annual rate. Continuous compounding uses e^r − 1.

Nominal annual rate
Compounds per year
Effective annual rate

Step-by-step solved example

Nominal 12% compounded monthly. Find the effective annual rate.

P12345An
Nominal vs effective rate on the same cash-flow axis.
  1. 1. Identify

    r = 0.12, m = 12.

  2. 2. Effective

    ie = (1 + 0.12/12)^12 − 1 = (1.01)^12 − 1 = 0.1268 = 12.68%.

Answer: 12.68% per year

10 practice questions

0/10 correct

1.12% compounded quarterly has m =

2.Effective rate for 12% compounded quarterly is nearest

3.For a given r, increasing m makes ie

4.If compounding is annual, ie equals

5.Continuous compounding of 10% nominal gives ie nearest

6.Period rate when r = 12% monthly compounding is

7.APR quoted without compounding frequency is treated as

8.(1 + r/m)^m − 1 is independent of

9.6% compounded semiannually → ie nearest

10.Compare alternatives with different compounding using