Use this free compound interest calculator to calculate compound interest on your savings or investment in seconds. Enter the starting amount, the annual interest rate, and the number of years, and the compound interest calculator shows the final balance and the interest earned instantly — no sign-up, no account, and no personal information needed. Your numbers are calculated in your browser and are not sent to us.
Contents: Formula · How to use · Examples · Tips · FAQ · Related toolsSources
No sign-up required. This compound interest calculator works in your browser, so the amounts you enter are not stored or sent to us The result is an estimate for general planning, not financial advice.
How to Calculate Compound Interest
Compound interest means you earn interest not only on your starting amount, but also on the interest already earned. That is why savings grow faster over time than with simple interest, where interest is paid only on the original amount.
Final balance A = P × (1 + r ÷ n)^(n × t)
Here P is the starting amount, r is the annual interest rate as a decimal, n is how many times interest is compounded each year, and t is the number of years. Interest earned is then A − P. For example, $10,000 at 5% compounded yearly for 10 years gives $10,000 × 1.05^10 = $16,288.95, so the interest earned is $6,288.95. This compound interest calculator uses exactly this formula, and it works in dollars, pounds, Canadian dollars, or any other currency.
How to Use the Compound Interest Calculator
Type the starting amount into the first box, the annual interest rate as a percentage into the second box — for 5%, type 5, not 0.05 — and the number of years into the third box. Choose how often interest is compounded: yearly, half-yearly, quarterly, or monthly. Tap Calculate Compound Interest to see the final balance and the interest earned. More frequent compounding gives a slightly higher balance, because interest starts earning interest sooner.
Remember that this compound interest calculator shows growth before tax and before any fees, and it assumes the rate stays the same for the whole period and that no money is added or withdrawn. Real accounts can differ, so treat the result as an estimate for planning, not as a promise from a bank.
Compound Interest Calculator Examples
Example 1 — $10,000 at 5% yearly for 10 years. Final balance = $10,000 × 1.05^10 = $16,288.95. Interest earned = $6,288.95.
Example 2 — $5,000 at 4% yearly for 5 years. Final balance = $5,000 × 1.04^5 = $6,083.26. Interest earned = $1,083.26.
Example 3 — $1,000 at 6% compounded monthly for 3 years. Final balance = $1,000 × (1 + 0.06 ÷ 12)^36 = $1,196.68. Interest earned = $196.68.
These compound interest calculator examples show the power of time: a longer period and a higher rate both raise the final balance, and monthly compounding adds a little extra compared with yearly compounding at the same rate.
Compound Interest Calculator Tips
Start early when you can, because time matters more than most people expect — money left to compound for 20 years grows far more than the same amount left for 10 years. Compare accounts on the final balance, not just the headline rate, because compounding frequency changes the result. For a plain explanation of the concept, see Investopedia's guide to compound interest. If you are comparing a loan instead of savings, the home loan calculator shows monthly payments, which is a different question from growth over time.
Compound Interest Calculator FAQ
What does a compound interest calculator do? A compound interest calculator works out how a starting amount grows when interest is earned on both the original amount and the interest already earned, over a set number of years.
What is the difference between compound and simple interest? Simple interest is paid only on the original amount, while compound interest is paid on the original amount plus past interest, so the balance grows faster over time.
How do I calculate compound interest by hand? Use A = P × (1 + r ÷ n)^(n × t), then subtract P to get the interest earned. The compound interest calculator does this arithmetic for you.
Does compounding frequency matter? Yes, but only slightly. Monthly compounding gives a higher balance than yearly compounding at the same annual rate, because interest starts earning interest sooner.
Why does the balance grow faster over time? Because each year's interest is added to the balance, so later interest is earned on a larger amount, not only on the starting amount.
>Can I use it for a loan? The same formula describes growth, but a loan with regular repayments is different, because the balance falls as you pay it back. Use the home loan calculator for monthly loan payments.
Related Tools
Try the Home Loan Calculator for monthly loan payments, the Discount Calculator to find a sale price, the Percentage Increase Calculator to measure a change, and the Reverse Sales Tax Calculator to remove tax from a total. Return to the PDGPT homepage to browse all free calculators by category.
Sources and Method
This calculator uses the standard compound interest formula A = P x (1 + r / n)^(n x t), with interest earned as A - P. Results are estimates for general planning, not financial advice. Last updated: October 28, 2026.
For interest compounded every day instead of yearly, half-yearly, quarterly, or monthly, try the Daily Compound Interest Calculator.