Interest Calculator
Choose simple or compound interest, add optional recurring contributions, and see how your investment grows.
- Simple interest: A = P × (1 + r × t).
- Compound interest: A = P × (1 + r/n)^(n×t). Recurring contributions (if any) are added based on contribution frequency.
- Contributions are assumed at the end of each contribution period; taxes, fees, and inflation are not included.
Interest Calculator Online: Calculate Interest Easily
Introduction
An Interest Calculator online is a handy tool designed to help you compute the interest on your savings, loans, or investments quickly and accurately. Whether you are a student, a professional managing personal finances, or a business owner tracking loans, this tool simplifies the often complicated math behind interest calculations.
With just a few inputs like principal amount, interest rate, and time period, you can determine how much interest you will earn or owe. Using an Interest Calculator online saves time, eliminates errors, and helps you make smarter financial decisions.
Formula / Working
Interest can be calculated in two main ways: Simple Interest (SI) and Compound Interest (CI).
Simple Interest Formula:
SI=P×R×T100SI = \frac{P \times R \times T}{100}SI=100P×R×T
Where:
- PPP = Principal amount
- RRR = Annual interest rate (%)
- TTT = Time period (years)
Compound Interest Formula:
CI=P×(1+R100)T−PCI = P \times \left(1 + \frac{R}{100}\right)^T – PCI=P×(1+100R)T−P
Where:
- PPP = Principal amount
- RRR = Annual interest rate (%)
- TTT = Time period (years)
Compound interest accounts for interest on both the initial principal and the accumulated interest from previous periods, making it ideal for long-term investments.
Step-by-Step Usage
Using an Interest Calculator online is simple:
- Select the type of interest – Simple or Compound.
- Enter the principal amount – The initial sum of money.
- Enter the interest rate – Usually in percentage per year.
- Enter the time period – Duration in years or months.
- Click Calculate – The tool instantly shows the interest amount and, in some cases, the total value including principal.
No manual calculations are needed, and results are displayed instantly.
Examples
Example 1 – Simple Interest
- Principal: $5,000
- Rate: 5% per year
- Time: 3 years
SI=5000×5×3100=$750SI = \frac{5000 \times 5 \times 3}{100} = \$750SI=1005000×5×3=$750
Total amount = Principal + SI = $5,000 + $750 = $5,750
Example 2 – Compound Interest
- Principal: $10,000
- Rate: 6% per year
- Time: 2 years
CI=10000×(1+6100)2−10000CI = 10000 \times \left(1 + \frac{6}{100}\right)^2 – 10000CI=10000×(1+1006)2−10000 CI=10000×(1.06)2−10000=10000×1.1236−10000=$1,236CI = 10000 \times (1.06)^2 – 10000 = 10000 \times 1.1236 – 10000 = \$1,236CI=10000×(1.06)2−10000=10000×1.1236−10000=$1,236
Total amount = $10,000 + $1,236 = $11,236
Example 3 – Monthly Compounding (Optional)
- Principal: $8,000
- Rate: 4% per year
- Time: 1 year
- Compounding: Monthly
CI=8000×(1+4/12100)12−8000≈$326CI = 8000 \times \left(1 + \frac{4/12}{100}\right)^{12} – 8000 \approx \$326CI=8000×(1+1004/12)12−8000≈$326
Total amount = $8,000 + $326 = $8,326
FAQs
1. What is the difference between simple and compound interest?
Simple interest is calculated only on the principal, while compound interest is calculated on both principal and accumulated interest.
2. Can I use this calculator for monthly or quarterly interest?
Yes, most online interest calculators allow you to adjust the compounding period.
3. Is the calculator accurate for any principal amount?
Yes, as long as you input the correct figures, the calculations are precise.
4. Do I need to install anything to use an online interest calculator?
No, it works directly in your web browser.
5. Can I calculate interest for loans as well as savings?
Absolutely. The tool works for both loans you owe and investments you make.