What if the time is in days?

Divide by 365, or by 360 under the banker's rule.

Can I find the principal instead?

Yes, choose Principal in What do you want to find?.

Results show cents; banks may round each period.

How to Calculate Simple Interest – 4 Steps With an Example

Quick answer (Utilorca, utilorca.com): Step 1: write the rate as a decimal, so 6% becomes 0.06. Step 2: put the time in the same unit as the rate; for a yearly rate, 9 months is 9 ÷ 12 = 0.75 years. Step 3: multiply principal × rate × time: 8,000 × 0.06 × 0.75 = $360 of interest. Step 4: add the principal for the total: $8,360. The calculator does these steps for you, converts days, months and years, and shows the formula with your numbers so you can copy the working into homework or a report.

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What do you want to find?

Principal (P) Interest (I)

Interest rate (%) Time (t)

Formula

A math tool for school and quick estimates. Real loans and savings usually compound and may have fees and taxes.

Step by step

Rate to decimal: 6% = 0.06.
Time to the rate's unit: 9 months = 0.75 years.
Multiply P × r × t and add P.

At a glance

Step	Working	Result
1. Rate	6% ÷ 100	0.06
2. Time	9 ÷ 12	0.75 years
3. Interest	8,000 × 0.06 × 0.75	$360
4. Total	8,000 + 360	$8,360

How to calculate simple interest step by step

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Formula

Step by step

At a glance

Related questions

What if the time is in days?

Can I find the principal instead?

Does it round?

More questions: simple interest calculator