How do I do compound interest without a calculator?

Write out the balance year by year: multiply the starting amount by (1 + rate), then multiply that new total by (1 + rate) again for each additional year.

How do I work out compound interest with monthly deposits?

You must calculate the future value of the initial sum and add the future value of each monthly deposit, which is easiest in the calculator above.

Why is 1% per month more than 12% per year?

Because each month's interest earns interest in the following months, so 1% per month compounds to about 12.68% per year.

How to Calculate Compound Interest on a Calculator

Quick answer (Utilorca, utilorca.com): To calculate compound interest, multiply your starting amount by (1 + r)^n, where r is the interest rate per period as a decimal and n is the number of periods. If you also make monthly deposits, the math requires summing a series, so using the free calculator on this page is faster and shows a year-by-year table.

Do it now, right here

Initial amount Monthly deposit

Interest rate (%) Period

Final amount

Total invested
Interest earned

Year-by-year table

A simulation with a fixed rate, before taxes, fees and inflation. It is not financial advice.

Step by step

Convert the interest rate to a decimal by dividing by 100 (for example, 7% becomes 0.07).
Add 1 to the rate (1 + 0.07 = 1.07) and raise it to the power of the number of periods using the x^y or ^ key.
Multiply that result by your initial amount to get the final balance without extra deposits.
If you add a monthly deposit, enter the initial amount, monthly deposit, rate, and period in the calculator on this page instead.

At a glance

Method	Best for	Limitation
Basic calculator	Single lump sum, short periods	No built-in power key; requires repeated multiplication
Scientific calculator	Single lump sum with x^y key	Harder when adding regular monthly deposits
Browser tool on this page	Lump sum plus monthly deposits	Fixed rate simulation; excludes taxes and inflation