Free Simple Interest Calculator - Easy Interest Calculations
Calculate simple interest instantly using the I = PRT formula. Best free simple interest calculator 2025 for loans, investments, and financial planning.
Quick Answer
Simple interest is calculated only on the original principal using the formula I = P × R × T, where I is interest, P is principal, R is annual rate (as decimal), and T is time in years. Unlike compound interest, simple interest does not earn interest on interest. Calculate instantly at practicalwebtools.com.
Key Facts about Simple Interest Calculator:
- Simple interest formula: I = P × R × T (Principal × Rate × Time)
- Interest is calculated only on original principal, not accumulated interest
- Common for short-term loans, car loans, and some bonds
- Simple interest grows linearly; compound interest grows exponentially
- $10,000 at 5% simple interest for 3 years = $1,500 interest
- Total amount = Principal + Interest = P × (1 + RT)
- Auto loans often use simple interest calculation
Why Use Our Simple Interest Calculator?
Quick and easy interest calculations:
Instant Calculation
Calculate simple interest in seconds.
Total Amount
See principal plus interest combined.
Flexible Time Periods
Calculate in years, months, or days.
Simple Formula
Easy to understand I = PRT calculation.
No Signup Required
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Calculations stay on your device.
How to Simple Interest Calculator in 3 Easy Steps
Calculate in 3 steps:
Enter Principal
The original amount of money.
Set Rate & Time
Annual interest rate and time period.
Get Results
See interest earned and total amount.
Simple Calculations, Clear Results
Understand basic interest concepts easily
Calculate short-term loan interest quickly
Compare to compound interest to see the difference
Plan for simple interest investments
Common Use Cases for Simple Interest Calculator
Perfect for:
Frequently Asked Questions
Everything you need to know about our simple interest calculator
What is simple interest?
Interest on principal only: I = P × R × T.
Simple interest is calculated only on the original principal amount. The formula is I = P × R × T where P is principal, R is annual rate as decimal, T is time in years.
What is the difference between simple and compound interest?
Simple: on principal only. Compound: on principal plus past interest.
Simple interest is calculated only on principal. Compound interest is calculated on principal plus accumulated interest, growing faster over time.
Which loans use simple interest?
Auto loans, some personal loans, and short-term loans.
Auto loans, some personal loans, and short-term loans often use simple interest. Mortgages and credit cards typically use compound interest.
How do I convert annual rate to monthly?
Divide annual rate by 12 for monthly rate.
For simple interest monthly calculation, use I = P × (R/12) × T, where T is now in months. Or calculate annual interest and divide by 12.
Still have questions? Try the tool yourself!
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