Simple Interest Calculator - Formula I = P × r × t (2026)
Calculate simple interest earned or owed using the standard formula I = P × r × t. Instant principal, rate, time, and end balance calculation.
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⚙️ Configuration & Inputs
$
%
years
📊 Results & Analysis
Total Simple Interest
$1,300.00
Ending Balance: $6,300.00
| Starting Principal (P) | $5,000.00 |
| Interest Rate (r) | 6.50% per year |
| Time Length (t) | 4.0 Years |
| Total Interest Earned / Owed (I) | $1,300.00 |
| Final Total Balance (A = P + I) | $6,300.00 |
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The Simple Interest Formula
I = P × r × t | Total A = P + I
Unlike compound interest—where interest accrues on accumulated interest—simple interest only calculates interest against the original principal amount. It is commonly used for short-term personal notes, automobile installment loans, and certificates of deposit (CDs).
Frequently Asked Questions
Simple interest calculates returns solely on the initial principal. Compound interest earns interest on both the principal and previous accumulated interest, causing exponential wealth growth over long horizons.