Financial / Browser calculator

Interest Calculator

Interest Calculator works from the inputs you provide and returns future balance, interest earned. Use the calculation panel to explore a scenario, then check the formula and limitations before applying the result.

Your inputs

Minimum: 0 · Maximum: 1000000000000
Minimum: 0 · Maximum: 100
Minimum: 0 · Maximum: 100
Minimum: 1 · Maximum: 366 · Whole numbers

Your results

Enter your values and calculate to see the result.

This estimate is for information and comparison, not financial, investment or tax advice.

Formula and calculation method

A = P × (1 + r / n)^(n × t). Interest earned = A − P.

Assumes the interest rate stays fixed, with interest reinvested. No contributions, taxes, withdrawals or early withdrawal penalties.

How to use interest calculator

  1. Set Principal / amount. The example below uses 100000.
  2. Set Annual interest rate (%). The example below uses 6.
  3. Set Years. The example below uses 5.
  4. Set Compounds per year. The example below uses 12.
  5. Select Calculate to update the result. Reset restores the illustrated inputs. Copy, print or download your own result if you need a record.

Worked example

Example inputs
Principal / amount
100000
Annual interest rate (%)
6
Years
5
Compounds per year
12
Future balance
134,885.01525493
Interest earned
34,885.01525493

Factors affecting your result

Assumes the interest rate stays fixed, with interest reinvested. No contributions, taxes, withdrawals or early withdrawal penalties.

Changing principal / amount changes the scenario being evaluated. Adjust one input at a time when comparing results, keep a copy of the assumptions, and compare values using the same unit and period. A precise arithmetic result does not make an uncertain assumption precise.

Frequently asked questions

How does the interest calculator work?

A = P × (1 + r / n)^(n × t). Interest earned = A − P.

What inputs does Interest Calculator need?

Enter principal / amount, annual interest rate (%), years, compounds per year. Read the unit labels; percentages are entered as ordinary percentages, not decimal fractions.

How should I interpret the interest calculator result?

Assumes the interest rate stays fixed, with interest reinvested. No contributions, taxes, withdrawals or early withdrawal penalties.

Are my interest calculator inputs uploaded?

No. The calculation runs in this browser. Favorites, recent tool names, theme and formatting preferences may be saved locally, but calculation inputs are not sent to a calculation server or stored by this website. Shared links do not include entered values.

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