Simple Interest Calculator
Calculate simple interest using SI = P × R × T ÷ 100. Supports years, months, days, and multiple currencies. Free global simple interest calculator.
How to Use
Step-by-step guide to get the most from this tool
- 1
Select currency
Choose INR, USD, EUR, or GBP for your calculation.
- 2
Enter principal and rate
Set the loan or investment amount and annual interest rate.
- 3
Set time period
Enter duration in years, months, or days.
- 4
Review results
See simple interest, total amount, formula breakdown, and interest growth chart.
Features
What makes this tool stand out
Multi-currency
INR, USD, EUR, and GBP support.
Formula shown
See the exact SI calculation breakdown.
Flexible time units
Years, months, or days.
Growth chart
Visualize interest accumulation over time.
Instant results
Live calculation as you type.
Free & global
No signup, works worldwide.
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Frequently Asked Questions
Quick answers to common questions
What is simple interest?+
Simple interest is calculated only on the principal amount, not on accumulated interest. Formula: SI = P × R × T ÷ 100, where P is principal, R is annual rate (%), and T is time in years.
How is simple interest different from compound interest?+
Simple interest stays constant each period. Compound interest earns interest on interest, growing faster over time. Use our Compound Interest Calculator to compare both.
Can I calculate SI for months or days?+
Yes. Select months or days as the time unit. The calculator converts to years automatically (months ÷ 12, days ÷ 365).
When is simple interest used?+
Simple interest is common in short-term personal loans, some car loans, student loans, and bonds. Many Indian microfinance and informal loans use simple interest.
What currencies are supported?+
Our calculator supports INR (₹), USD ($), EUR (€), and GBP (£). Select your currency from the dropdown before entering amounts.
Is simple interest better for borrowers?+
Yes. Simple interest results in lower total interest than compound interest for the same rate and period, making it cheaper for borrowers.
How do I convert monthly rate to annual?+
Multiply monthly rate by 12 for approximate annual rate. For precise calculations, use the annual rate directly in this calculator.
What is the Rule of 72?+
For compound interest, money doubles in approximately 72 ÷ rate years. Simple interest does not follow this rule since interest does not compound.