Compound Interest Calculator – Calculate CI Online

Principal Amount

Total intrest

Total Amount


Quick answer

Compound interest is interest earned on both your original principal and the interest already accumulated. Enter a principal, annual rate, compounding frequency and term to see the future value instantly.

Key facts

  • Free to use with no account or sign-up required
  • Runs in any modern web browser on desktop and mobile
  • Provided by A2Z Tools (a2z.tools)

What is this tool?

This calculator shows how an investment or loan grows when interest is compounded — that is, when each period's interest is added to the balance and itself earns interest in later periods.

How to use it

  1. Enter the required values into the calculator fields
  2. Click Calculate
  3. Read the result and the breakdown shown below the form

How it works

It applies the standard compound-interest formula:

A = P × (1 + r/n)n·t

  • A — final amount
  • P — principal
  • r — annual interest rate (decimal)
  • n — compounding periods per year
  • t — years

Interest earned is A - P.

Common use cases

  • Projecting savings-account or fixed-deposit growth
  • Comparing yearly vs monthly compounding offers
  • Estimating long-term investment outcomes

Limitations

The projection assumes a constant interest rate and no additional deposits or withdrawals. Real products may charge fees, change rates or use different day-count conventions, so treat the result as an estimate rather than financial advice.

Privacy & your data

All calculations run in your browser. The amounts you enter are never transmitted to our servers.

Frequently asked questions

What is the difference between simple and compound interest?

Simple interest is paid only on the principal. Compound interest is paid on the principal plus previously earned interest, so the balance grows faster over time.

How does compounding frequency affect the result?

More frequent compounding (monthly vs yearly) produces a slightly higher final amount at the same nominal rate, because interest starts earning interest sooner.

Can I use this for loans as well as savings?

Yes — the same formula describes how a debt grows if unpaid, which makes the calculator useful for understanding loan balances too.

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