Simple Interest Calculator
Interest on the principal only, nothing compounding: enter the amount, annual rate and time — in years, months or days — and get the interest and total instantly.
Try it
Nothing leaves your deviceEnter the principal, rate and time, then press Calculate — the interest appears here.
How to use this calculator
- Enter the principal — the original amount being lent, borrowed or deposited.
- Set the annual rate as a percentage, then enter the time and choose its unit (years, months or days).
- Press Calculate to see the simple interest, the total amount and the exact formula used.
- Copy or reset. Grab the full result with Copy Result, or Reset to start a new scenario.
Useful information
Simple interest is the straightforward version: the same percentage of the original principal is charged or earned every period. No interest is ever added to the base, so the growth is a straight line instead of a curve.
The formula
I = (P × R × T) ÷ 100, where P is the principal, R the annual rate and T the time in years. For ₹50,000 at 8% for 2 years: (50,000 × 8 × 2) ÷ 100 = ₹8,000, making the total ₹58,000.
Converting time
The rate is annual, so time must end up in years: months ÷ 12, days ÷ 365. The unit selector handles that for you — 18 months becomes 1.5 years automatically.
Simple vs compound
Compound interest pays “interest on interest”, so over long periods it pulls ahead quickly. If your product compounds (most savings accounts, FDs and mutual funds do), use the Compound Interest Calculator instead — this tool intentionally keeps things linear.
Reminder: this is an estimate for planning. Actual products may compound, add fees or count days differently (e.g. 360-day years) — check the fine print for anything formal.
Frequently asked questions
What is the simple interest formula?
Interest = (Principal × Rate × Time) ÷ 100. The total amount to repay is Principal + Interest. Rate is annual and time must be in years.
How do I enter time in months or days?
Pick the unit next to the time field. Months are converted as ÷ 12 and days as ÷ 365, so 18 months counts as 1.5 years and 90 days as about 0.2466 years.
What is the difference between simple and compound interest?
Simple interest is always calculated on the original principal only. Compound interest is calculated on the principal plus previously earned interest, so it grows faster over the same period.
Where is simple interest typically used?
Short-term personal loans, some car loans, credit-card style billing before compounding kicks in, and certain savings or bond payouts. Always check the actual terms — the method varies by product.
Are my numbers stored?
No. The calculation runs entirely in your browser — your amounts are never sent to a server or saved by Jivora.