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Compound Interest Calculator

See how your money grows โ€” future value, interest earned, and yearly growth.

Compounds
Future value
$1,647.01
Total interest
$647.01
Growth multiple
1.65ร—

A = 1,000.00 ร— (1 + 0.004166666666666667 )12ร—10.00 = $1,647.01

Year-by-Year Growth

Yr 1
$1,051.16
Yr 2
$1,104.94
Yr 3
$1,161.47
Yr 4
$1,220.90
Yr 5
$1,283.36
Yr 6
$1,349.02
Yr 7
$1,418.04
Yr 8
$1,490.59
Yr 9
$1,566.85
Yr 10
$1,647.01
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How Compound Interest Works

Compound interest is interest calculated on both the initial principal and the accumulated interest of previous periods โ€” โ€œinterest on interest.โ€ It is the engine behind savings accounts, retirement funds, and long-term investing, and also the reason unpaid credit-card debt snowballs so aggressively.

The Formula, Explained

A = P(1 + r/n)nt: start with principal P, add each periodโ€™s interest at rate r/n, and repeat nt times. More frequent compounding means each periodโ€™s interest starts earning sooner โ€” try switching between yearly and monthly above to see the gap.

The Rule of 72

A handy mental shortcut: divide 72 by your annual rate to estimate doubling time. At 6%, money doubles in about 12 years; at 9%, in about 8. Time matters more than most people expect โ€” starting ten years earlier can matter more than a higher rate.

Working with the percentages in these calculations? Try our percentage calculator or the four-function calculator.

Frequently Asked Questions

What is the compound interest formula?

A = P(1 + r/n)^(nt), where P is the principal, r is the annual rate as a decimal, n is the number of compounding periods per year, and t is the number of years. The calculator above applies it instantly.

What is the difference between compound and simple interest?

Simple interest pays only on the original principal, while compound interest pays on the principal plus all previously earned interest โ€” so the balance grows faster every period. Over long time spans the difference is enormous.

Does compounding frequency really matter?

Yes, but less than the rate and time. Monthly compounding beats yearly compounding at the same nominal rate because interest starts earning its own interest sooner. Daily compounding adds only a little more on top.

Is this compound interest calculator free?

Yes โ€” every tool on Math Solver Free is free with no sign-up, and all calculations run in your browser.