Interest Rate Calculator
Compute annual interest rate from principal and final amount, or compute final amount from principal and rate. Supports simple & compound interest.
No calculation yet — enter values and click Calculate.
- Simple: A = P × (1 + r × t)
- Compound: A = P × (1 + r/n)^(n × t) → r = n × ((A / P)^(1/(n t)) − 1)
- All rates shown as annual % (r × 100).
Result Details
Detailed step-by-step calculations and breakdown will appear here after running a calculation.
Compounding: Annual (n=1), Quarterly (n=4), Monthly (n=12), Weekly (n=52), Daily (n=365).
How the Interest Rate Calculator Works
The calculator determines the interest rate based on the principal amount, total interest earned or paid, and the time period. It uses standard financial formulas to compute the exact annual interest rate.
Required Inputs
1. Principal Amount
The original amount borrowed or invested.
2. Total Interest
The total amount of interest gained (investment) or paid (loan) over the selected time period.
3. Time Period
The duration in years, months, or days.
4. Compounding Frequency
You can select annual, monthly, quarterly, weekly, or daily compounding
Calculation Method
Simple Interest Formula
Used when compounding is not applied:
Interest Rate = (Interest ÷ (Principal × Time)) × 100
Compound Interest Formula
When compounding frequency is selected:
Rate = ( (A ÷ P)^(1 / (n × t)) − 1 ) × n × 100
- n = compounding periods
- t = time in years
Outputs Provided
1. Annual Interest Rate (%)
Shows the accurate yearly rate based on selected inputs.
2. Total Value at End
Displays the final amount including interest for compound calculations.
3. Comparison Chart
Shows simple vs compound interest difference over the selected period.
Use Cases
- Comparing investment growth
- Understanding loan rates
- Evaluating credit card or mortgage interest
- Checking returns for savings or fixed deposits
- Business and financial planning
Why Use This Calculator?
- Accurate simple and compound interest calculations
- Works for loans, savings, and investments
- Supports multiple compounding frequencies
- Gives clear breakdown of interest growth