Compound interest and savings calculator

Enter a starting amount, a regular deposit, a rate and a term. See the final balance and how much of it is interest.

The amount you start with. Enter 0 if you start from nothing.

Added each period. Enter 0 for none.

The nominal annual rate, before tax and fees.

Up to 1 decimal place, for example 2.5.

Final balance

0.00

What the account holds at the end of the term.

Your goal
-
Balance at the end
0.00
Total deposited
0.00
Interest earned
0.00
Effective annual rate
0.00%
Without the regular deposits
0.00

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For information only, not financial, tax or legal advice.

Last updated 2026-10-30. Method checked 2026-10-30. Methodology

This calculator shows how savings grow when interest is added to the balance and then earns interest of its own. Enter an initial deposit, an optional regular deposit, the yearly rate, how often interest is added and the number of years. You get the final balance, the total paid in, the interest earned, the effective annual rate and a year by year table you can read or download. It suits a savings account, a fixed deposit, a child's fund or any plan with a steady rate. Switch to Goal mode to enter a target and find the regular deposit that reaches it. The tool assumes the rate never changes. It leaves out tax on interest, account fees and inflation, so the real outcome will differ.

How to use the Compound Interest and Savings Calculator

  1. Enter the initial deposit and choose the currency. Enter 0 if you start from nothing.
  2. Enter the regular deposit and how often you make it, for example 200 a month.
  3. Enter the yearly interest rate and the number of years. Tip: Open the settings to change how often interest compounds, whether deposits land at the start or end of each period, or to switch to Goal mode.
  4. Read the final balance, the interest earned and the year by year table. Download the table as a CSV file if you need it.

Worked example

A saver starts with a lump sum and adds to it every month. All figures are USD.

InputValue
Initial depositUSD 10,000.00
Regular depositUSD 200.00, added at the end of each month
Yearly interest rate6%
CompoundingMonthly
Term10 years (120 months)
 
Monthly rate = 6% / 12 = 0.5% = 0.005
Growth factor over 120 months = (1.005)^120 = 1.81940
Initial deposit grows to 10,000 x 1.81940 = USD 18,193.97
Deposits grow to 200 x ((1.005)^120 - 1) / 0.005 = 200 x 163.8793 = USD 32,775.87
Final balance = 18,193.97 + 32,775.87 = USD 50,969.84
Total deposited = 10,000 + (200 x 120) = USD 34,000.00
Interest earned = 50,969.84 - 34,000.00 = USD 16,969.84
Final balance
USD 50,969.84
Total deposited
USD 34,000.00
Interest earned
USD 16,969.84
Effective annual rate
6.17%
Without the regular deposits
USD 18,193.97

The year by year table shows rounded snapshots, so the interest in one row can differ from the headline by a cent.

How it is calculated

A = P x (1 + r / n)^(n x t) + d x ((1 + i)^N - 1) / i

P is the initial deposit. r is the yearly rate as a decimal. n is how many times a year interest is added, such as 12 for monthly. t is the number of years. d is the regular deposit, i is the rate for one deposit period and N is the number of deposits. The final balance is the two parts added together.

By default each deposit lands at the end of its period. Choose the start of the period and every deposit earns one extra period of interest, which multiplies the deposit part by (1 + i). Interest earned is the final balance minus everything you paid in.

When deposits and compounding use the same frequency, the closed formula above gives the result. When they differ, for example weekly deposits with monthly compounding, the tool steps through the term period by period. Between compounding dates interest builds up on the credited balance and is added at the next date. Any interest still building at the end of the term is added then. Figures are kept at full precision and rounded only for display.

The effective annual rate is (1 + r / n)^n - 1. It shows the real yearly growth once compounding is counted. At 6% compounded monthly it is 6.17%.

In Goal mode the tool solves the same formula for the deposit: d = (target - P x (1 + i)^N) x i / ((1 + i)^N - 1). If the initial deposit already reaches the target, no regular deposit is needed. With a rate of 0, the deposit is simply (target - P) / N.

Frequently asked questions

What is compound interest in plain words?

It is interest that joins your balance and then earns interest too. Simple interest pays only on the original amount. Compound interest makes the balance grow a little faster each period. Over 10 years at 6%, a deposit of 10,000 reaches 16,000 with simple interest and about 18,194 with monthly compounding.

Does it matter how often interest compounds?

Slightly. A deposit of 10,000 at 6% for 10 years reaches about 17,908 with yearly compounding, 18,140 with quarterly and 18,194 with monthly. The effective annual rate shown in the results lets you compare accounts that compound at different speeds. The rate and the number of years move the result far more.

Does the calculator take off tax on the interest?

No. Many countries tax savings interest, and the rules depend on the country and the type of account. To allow for tax, enter a lower rate. For example, use 4.8% instead of 6% if 20% of the interest goes to tax. Otherwise read the result as a figure before tax.

What is the rule of 72?

It is a quick way to estimate how long money takes to double. Divide 72 by the yearly rate. At 6% the answer is about 12 years, and at 9% it is about 8 years. It is only an approximation. For 6% compounded monthly, the exact doubling time is about 11 years and 7 months.

Can I use it for a fixed or term deposit?

Yes. Enter the amount as the initial deposit, set the regular deposit to 0 and enter the rate the bank quotes. Then set compounding to match the bank terms, which is often quarterly or yearly for term deposits. The final balance is the maturity amount before any tax or fees.

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