Calcumetrics LogoCalcumetrics

Compound Interest Calculator

Calculate the future value and interest earned with flexible compounding frequencies.

₹

Starting investment amount

%

Nominal annual interest rate

Years

Duration of compounding

How often interest is compounded onto principal

Compounding Rule

More frequent compounding increases the effective yield. For example, monthly compounding on 8% yields an effective annual rate of 8.30%.

Results

Future Value
₹2,15,892
Initial Principal₹1,00,000
Total Interest Earned₹1,15,892
Total Return115.9%

For information only. Not financial advice. Results are estimates.

How this calculator works

Compound interest is calculated using the exponential growth formula where interest earned in each period is added to the principal balance for the next period:

A = P × (1 + r / n)n × t

  • A — Final maturity amount (future value)
  • P — Initial principal balance
  • r — Annual nominal interest rate (as a decimal, e.g. 0.08 for 8%)
  • n — Number of times interest is compounded per year
  • t — Number of years

The total interest earned is A − P. The effective annual rate (EAR) is (1 + r/n)n − 1, which shows the true annual yield accounting for compounding frequency.

Worked example

Given: P = ₹1,00,000, r = 8% (0.08), n = 1 (annual), t = 10 years

Step 1: Calculate the growth factor

(1 + 0.08 / 1)1 × 10 = 1.0810 = 2.15892

Step 2: Calculate the future value

A = 1,00,000 × 2.15892 = ₹2,15,892

Step 3: Calculate interest earned

Interest = ₹2,15,892 − ₹1,00,000 = ₹1,15,892

Step 4: Calculate total return

Return = (₹1,15,892 / ₹1,00,000) × 100 = 115.9%

If the same investment were compounded monthly instead of annually, the future value would be ₹2,21,964 — an additional ₹6,072 from more frequent compounding.

Assumptions

  • The interest rate remains constant throughout the investment period.
  • Interest is reinvested at the same rate — no withdrawals during the tenure.
  • The calculation does not account for taxes on interest earned, fees, or inflation.
  • Compounding occurs at the selected frequency (annually, semi-annually, quarterly, monthly, or daily).
Confused about nominal rates vs. compounding frequencies?Read our in-depth guide on APR vs. APY: Why Compounding Frequency Changes Your Real Interest Rate to see mathematical proofs, frequency tables, and disclosure traps across loans and savings products.

Frequently asked questions

What is the difference between simple and compound interest?
Simple interest is calculated only on the initial principal amount. Compound interest is calculated on both the principal and all accumulated interest from preceding periods. Over longer periods, compound interest grows much faster due to the snowball effect. For example, ₹1,00,000 at 8% for 10 years earns ₹80,000 with simple interest but ₹1,15,892 with annual compound interest.
What is the effective annual rate (EAR)?
EAR = (1 + r/n)n − 1. It represents the true annual rate you earn when compounding happens more frequently than once a year. For example, a nominal rate of 8% compounded monthly gives an EAR of approximately 8.30%, meaning you effectively earn 8.30% per year rather than 8%.
How does compounding frequency affect returns?
More frequent compounding yields higher returns because interest is added to the principal more often, creating a larger base for the next period. For ₹1,00,000 at 8% over 10 years: annual compounding gives ₹2,15,893, quarterly gives ₹2,20,804, monthly gives ₹2,21,964, and daily gives ₹2,22,535. The difference between annual and daily compounding is ₹6,643 — significant over larger amounts and longer periods.
What is the Rule of 72?
The Rule of 72 is a quick estimation method: divide 72 by the annual interest rate to approximate how many years it takes to double your money with compound interest. At 8% annual compounding, your money approximately doubles in 72 ÷ 8 = 9 years. The exact answer (using the formula) is 9.006 years, making the Rule of 72 remarkably accurate for typical interest rates.
Is the compound interest result guaranteed?
No. This calculator provides a mathematical estimate based on a constant assumed rate. Fixed deposits and government bonds offer guaranteed rates, but market-linked instruments (mutual funds, equities) fluctuate and actual returns may differ substantially. The result is for educational and planning purposes only, not financial advice.

Related calculators

Investments

SIP Calculator

Calculate maturity value and wealth gain for Systematic Investment Plans with monthly compounding.

Investments

Lump Sum Calculator

Calculate the future value of a one-time investment with compound interest.

Investments

Simple Interest Calculator

Calculate simple interest, maturity value, and compare directly with compound interest growth.

Future Value

₹2,15,892