Simple Interest Calculator
Interest and total amount on the flat simple-interest basis used for short-term and informal loans.
Inputs
365 days = 1 year
Formula
- SI = P × R × T / 100 (T in years)
- T = days / 365
- Amount = P + SI
- Equivalent compound rate = ((A/P)^(1/T) − 1) × 100
Simple interest is charged only on the original principal, never on accumulated interest. It is used for short-tenure bridging finance, trade credit and many informal loans. Because a flat rate ignores the repayments already made, a 'flat 10%' loan repaid monthly costs nearly twice that in reducing-balance terms.
Step-by-step calculation
- 1
Time in years
365 / 365
1.0000
- 2
Simple interest
100,000 × 12 × 1.000 / 100
₹12,000.00
- 3
Amount
100,000 + 12,000
₹112,000.00
Assumptions
- 365-day year
- No compounding and no intermediate repayments
Tips
- Always convert a quoted flat rate to a reducing-balance rate before comparing with a bank loan.
Warnings
- Flat-rate vehicle and consumer loans understate the true cost — ask for the reducing-balance APR.
Standards & references
- Simple interest convention (Actual/365)
Frequently asked questions
What does the Simple Interest Calculator do?
Interest and total amount on the flat simple-interest basis used for short-term and informal loans. The Simple Interest Calculator on OneCalcApp returns the result instantly as you type, together with the formula and the substituted values.
How do I use the Simple Interest Calculator?
Enter your values in the input fields, choose the relevant units or options, and the Simple Interest Calculator recalculates automatically. You can copy, print or export the result.
Is the Simple Interest Calculator free to use?
Yes. The Simple Interest Calculator is completely free, needs no sign-up and has no usage limit on OneCalcApp.
How accurate is the Simple Interest Calculator?
It uses the standard formula SI = P × R × T / 100 (T in years) and full double-precision arithmetic, so results match a manual calculation to the displayed number of digits.
Does the Simple Interest Calculator work on mobile and offline?
Yes. The Simple Interest Calculator runs entirely in your browser on phones, tablets and desktops, and your inputs never leave your device.
Where can I find related tools?
OneCalcApp hosts 300+ calculators and converters, including the full Finance collection. Related tools are linked at the bottom of every page.
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