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Financial Planning

Compound Interest Calculator

See how a deposit and regular contributions grow when interest is compounded, with any compounding frequency, including continuous.

Your inputs

Results

Future value

$16,470.09

Total deposits
$10,000.00
Total interest earned
$6,470.09
Effective annual rate
5.1162%

✓Exact calculation — rounded only for display

Show calculation steps
  1. Rate per month: i = 0.416667%
  2. Number of periods: N = 120
  3. Growth of initial deposit: 10000 × (1 + i)^120 = 16470.09
  4. Growth of contributions: 0

Inputs are never added to links for financial, salary or health calculators.

What this calculator does

Compound interest pays interest on previously earned interest, so balances grow faster over time than with simple interest. Use this to compare compounding frequencies, test the effect of monthly saving, or see how long-term growth builds.

Formula and method

FV = P(1 + i)^N + C × [((1 + i)^N − 1) / i] × (1 + i if contributions are at the start) where i is the effective rate per contribution period: i = (1 + r/m)^(m/p) − 1 (or e^(r/p) − 1 for continuous compounding).
P
initial deposit
C
regular contribution
r
nominal annual rate
m
compounding periods per year
p
contributions per year
N
number of contribution periods

Worked example

Calculated by this tool with its default inputs:

Inputs

  • Initial deposit: 10000 (any currency)
  • Annual interest rate (nominal): 5 %
  • Compounding frequency: Monthly
  • Time period: 10 years
  • Regular contribution: 0 (any currency)
  • Contribution frequency: Monthly
  • Contributions made at: End of each period

Results

  • Future value: 16,470.09
  • Total deposits: 10,000
  • Total interest earned: 6,470.09
  • Effective annual rate: 5.1162%

How to read the results

Future value is what the account would hold at the end. The gap between it and total deposits is the interest earned; the effective annual rate shows the true yearly growth after compounding.

Assumptions and limitations

  • Assumes a constant rate, no withdrawals, fees or taxes.
  • When contributions and compounding happen at different frequencies, the rate is converted to an equivalent rate per contribution period.
  • Results are estimates for planning and education, not individual financial advice.

Financial results are estimates based on the inputs and assumptions shown. They are not financial advice; confirm figures with your lender, provider or a qualified adviser before making decisions.

Questions

Does more frequent compounding make a big difference?

It helps, but with diminishing returns. At 5 % a year, monthly compounding gives an effective 5.116 %, while daily gives about 5.127 % — the rate and time invested matter far more.

What does contributions “at the beginning” change?

Each deposit earns one extra period of interest, so the result is the end-of-period value multiplied by (1 + i).

Methodology and verification

Result type
Exact mathematical calculation (rounded only for display)
Formula version
1.0
Automated verification
8 reference and validation test cases, checked against independently computed values. The site cannot be built if any of them fail.
Editorial review
Awaiting human editorial review. The explanation was drafted with AI assistance; the formula and examples are verified by the automated tests above.

Privacy

Everything you enter is calculated in this browser and is not sent to Numerith or anyone else. Because this calculator can involve personal financial or health details, your inputs are never added to share links or saved to history. Privacy policy