Financial Tool

Compound Interest Calculator

Visualize the power of compound interest. Calculate investment growth over time for savings, 401(k)s, and crypto.

Σ The Formula

A = P(1 + r/n)^(nt)

Real World Examples

Retirement Savings
$10,000 at 7% for 30 years: Grows to $81,164.97
College Fund
$5,000 at 5% monthly compounding for 18 years: Grows to $12,284.09
High Yield Savings
$20,000 at 4.5% daily compounding for 1 year: Grows to $20,919.26

# About This Calculator

The Compound Interest Calculator demonstrates the incredible potential of exponential growth. Often called the "eighth wonder of the world," compound interest allows your money to earn interest on itself, accelerating wealth accumulation over long periods. It is the fundamental principle behind retirement savings, stock market investing, and even inflation.

How Compound Interest Works

  • P (Principal): Your starting investment.
  • r (Annual Rate): The expected return (decimal).
  • n (Frequency): How often interest is added (e.g., 12 for monthly).
  • t (Time): How long the money grows (years).

Real-World Examples

The Snowball Effect

Imagine a snowball rolling down a hill. It starts small, but as it gathers more snow (interest), it grows larger and faster. In investing, the "snow" is your interest earning more interest.

Debt Danger

Compound interest works both ways. Credit card debt compounds daily, meaning if you don't pay it off, your debt grows exponentially.

Frequency Matters

The more frequently interest compounds, the more money you make. Finding an account that compounds Daily is better than Monthly, though the difference is usually small for short periods. Over 30 years, however, those small differences add up!

How To Use

  1. Enter your **Principal** (Initial Investment).
  2. Enter the expected **Interest Rate** (Annual %).
  3. Enter the **Time Period** in years.
  4. Select **Compounding Frequency** (Monthly is standard for most savings).
  5. Click **Calculate** to see your future balance.

Frequently Asked Questions

What is the Rule of 72?+

It's a mental math shortcut to estimate how long it takes to double your money. Divide 72 by your interest rate. Example: At 8% interest, 72/8 = 9 years to double.

What's continuous compounding?+

The theoretical limit where compounding happens infinitely often. Formula: A = Pe^(rt). In practice, daily compounding is nearly identical to continuous for most personal finance purposes.

Does inflation affect my returns?+

Yes. While this calculator shows nominal growth (number of dollars), inflation reduces the purchasing power of those dollars. A 7% return with 3% inflation is effectively a 4% 'real' return.

What is the difference between APR and APY?+

APR is the simple interest rate. APY (Annual Percentage Yield) includes the effect of compounding, giving you a truer picture of your actual earnings (or costs) over a year. APY is always higher than APR when compounding exists.

Does compounding frequency really matter?+

Yes, but with diminishing returns. The jump from Annual to Monthly is significant. The jump from Monthly to Daily is tiny. For $10k at 5% for 10 years: Annual=$16,288 vs Daily=$16,486.

Is Compound Interest Calculator free to use?+

Yes, Compound Interest Calculator on Matheric is completely free to use. We believe in accessible education and utility for everyone.

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