Simple Interest Calculator

The classic I = Prt. Simple interest ignores compounding — common in short-term notes and some auto loans.

Principal

Annual rate

Time

years

Interest earned/owed

$1,800.00

How the Simple Interest Calculator works

The calculation follows the standard method used across the US — no shortcuts, no hidden assumptions. Here is exactly what happens behind the scenes:

365 vs 360 day counts?

Consumer loans typically use actual/365; some commercial notes use 360, quietly raising effective cost ~1.4%. Check your note.

Why would anyone use simple interest?

Transparency and early-payoff fairness: interest accrues strictly on outstanding principal daily, so paying early always saves full future interest.