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Compound Interest Calculator - Calculate Investment Growth

A Compound Interest Calculator is a financial tool used to estimate how money grows over time when interest is added back to the principal. Unlike simple interest, compound interest is calculated on both the initial amount and the accumulated interest from previous periods. This makes it especially useful for savings plans, long-term investments, retirement projections, and loan growth analysis.

Compound Interest Formula

A = P × (1 + r/n)^(n×t)Formula: Interest = A - P

Variables:

  • AFinal amount (principal + interest)
    Final amount (principal + interest)(e.g.: $1,610)
  • PInitial principal
    Initial principal(e.g.: $1,000)
  • rAnnual interest rate (in decimal)
    Annual interest rate (in decimal)(e.g.: 0.10 (10%))
  • nCompounding frequency per year
    Compounding frequency per year(e.g.: 12 (monthly))
  • tTime period (in years)
    Time period (in years)(e.g.: 5 years)

Categories:

Dailyn = 365, compounding every day
Monthlyn = 12, compounding every month
Quarterlyn = 4, compounding every 3 months
Annuallyn = 1, compounding every year

How to Use the Compound Interest Calculator

  1. 1

    Enter Initial Principal

    Enter the amount of money to be invested or saved as the initial principal.

  2. 2

    Enter Interest Rate

    Enter the annual interest rate in percent. Example: for 10% interest per year, enter 10.

  3. 3

    Select Compounding Frequency

    Choose how often interest compounds: daily, monthly, quarterly, or annually.

  4. 4

    Enter Time Period

    Enter the investment duration in years to see your money's projected growth.

Examples

Example 1: 5-Year Time Deposit

Problem:

You deposit $10,000 with 6% annual interest, compounded monthly, for 5 years. What is the final value?

Solution:
  1. 1.P = 10,000, r = 0.06, n = 12, t = 5
  2. 2.A = 10,000 × (1 + 0.06/12)^(12×5)
  3. 3.A = 10,000 × (1.005)^60
  4. 4.A = 10,000 × 1.3489 = 13,489
Result:$13,489

After 5 years, your money grows to $13,489. Total interest earned: $3,489

Example 2: Child Education Savings

Problem:

A parent saves $2,000 per month with 5% annual interest compounded monthly. After 10 years, what is the total savings?

Solution:
  1. 1.Use the annuity formula for regular savings
  2. 2.A = 2,000 × [((1 + 0.05/12)^(12×10) - 1) / (0.05/12)]
  3. 3.A = 2,000 × [((1.00417)^120 - 1) / 0.00417]
  4. 4.A = 2,000 × 155.28 = 310,560
Result:$310,560

In 10 years, total savings reach $310,560 with principal deposits of $240,000. Interest earned: $70,560.

Frequently Asked Questions

What is the difference between compound interest and simple interest?
Simple interest only calculates interest on the initial principal: I = P × r × t. Compound interest calculates interest on the principal plus accumulated interest, resulting in exponential growth. Over the long term, compound interest yields significantly greater returns. Example: $10,000 at 10% for 10 years, simple interest yields $20,000, compound interest yields $25,900.
What is the 'Rule of 72'?
The Rule of 72 is a quick way to estimate how long it takes for money to double. Divide 72 by the interest rate to get the approximate time. Example: 6% interest, time = 72/6 = 12 years to double. This formula applies to compound interest and is very popular among investors for quick planning.
Which compounding frequency is most profitable?
The more frequently compounding occurs, the greater the return. Ranking from lowest to highest: annual < semi-annual < quarterly < monthly < daily < continuous. However, the difference becomes smaller at higher frequencies. For savings accounts and time deposits, monthly compounding is the most commonly offered by banks.
Does compound interest only apply to investments?
No. Compound interest also applies to debts such as credit cards and online loans. This is why debt can balloon quickly if not paid off - interest keeps accruing on interest. It's important to pay off compound interest debt as soon as possible.
How does inflation affect compound interest?
To calculate real growth, subtract the inflation rate from the nominal interest rate. If a deposit earns 6% and inflation is 3%, your real return is only about 3%. A good investment should outpace inflation.

Related Calculators

Simple Interest

Simple interest calculation

ROI

Return on Investment

CAGR

Compound Annual Growth Rate

Pension Fund

Retirement financial planning

Inflation

Impact of inflation on investments

References