---
title: "Simple Interest Calculator — I = PRT Formula (vs Compound Interest)"
description: "Calculate simple interest using I = P × r × t. Compare simple vs compound interest. Understand when each is used globally — Treasury bills, auto loans, savings accounts. Free."
url: "https://worldcalculators.org/calculators/simple-interest/"
canonical: "https://worldcalculators.org/calculators/simple-interest/"
---

# Simple Interest Calculator

Calculate simple interest using I = P × r × t. Compare simple vs compound interest. Understand when each is used globally — Treasury bills, auto loans, savings accounts. Free.

## Quick Answer

$10,000 at 5% for 10 years: Simple interest = $5,000 (total $15,000). Compound interest (annual) = $6,289 (total $16,289). Compound earns $1,289 more — with the gap growing exponentially over longer periods.

## Sources & Methodology

Simple interest uses I = P × r × t with no compounding, unlike the compound interest applied to most modern savings and loan products. Short-term instruments such as US Treasury bills are quoted on a simple-interest basis.

Source: https://worldcalculators.org/calculators/simple-interest/
Markdown mirror of the HTML page. Prefer this URL for RAG; the interactive calculator still lives on the HTML page.