Compound Interest Calculator

Use this free compound interest calculator to estimate future value, total contributions, and interest from principal, deposits, rate, time, and compounding frequency.

All tools

Formula steps Estimate limits shown Examples included Private history

Initial amount ($)Monthly contribution ($)Annual rate (%)Time (years)Compounding

Compound interest balance$18,207.33

$1,000 plus $100.00/mo at 6%

Total contributions: $13,000.00
Estimated interest: $5,207.33
Effective annual rate: 6.1677811865%

Formula steps

Compound 12 times per year.
Convert compounding to an effective annual rate.
Convert effective annual growth to monthly growth for contributions.
Ending balance includes starting amount, monthly contributions, and estimated interest.

How to use the compound interest calculator

Enter the requested dollar amounts, rates, terms, tax settings, or contribution details.
Use rates as percentages, such as 6.5 for 6.5%, and check whether a field asks for a monthly or annual amount.
Press the calculate button to see the answer, supporting metrics, and formula steps.
Use the result as a planning estimate only, then copy it if the assumptions look right.

Common uses

Estimate how compound interest can grow savings over time.

Compare monthly deposits with a starting amount.

Test annual, quarterly, monthly, or daily compounding assumptions.

Separate contributions from estimated interest earned.

Examples

Savings growth $1,000, $100/month, 6%, 10 years

Projected future value

Daily compounding $5,000 at 4.5%, daily

Effective-rate estimate

No deposits $10,000 at 5% for 20 years

Compound-only balance

Frequently asked questions

Quick answers about formulas, rates, payment assumptions, estimate limits, examples, and private in-browser history.

What can I use the Compound Interest Calculator for?

Use it for quick planning, comparison, and what-if estimates before you check exact numbers with a lender, tax professional, payroll provider, or financial adviser.

How does the Compound Interest Calculator calculate the result?

The calculator converts the stated annual rate to an effective monthly growth rate from the selected compounding frequency, then compounds principal and monthly deposits.

Is this financial, tax, or legal advice?

This calculator gives an educational estimate only. It does not include every fee, lender rule, tax rule, local rate, credit, penalty, or personal financial detail.

Are my finance inputs private?

Yes. The calculator runs in your browser tab. Recent answers stay only on the page while you use it and are not sent to a server.