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Simple Interest Calculator

Calculate simple interest and total amount

Principal Amount ($)
Interest Rate (%)
Time (years)
Compounding

Simple Interest Formula

Simple Interest (I) = P × r × t
Total Amount (A) = P + I = P(1 + r×t)
P = Principal, r = Annual rate, t = Time in years

Simple interest is straightforward - interest is calculated only on the original principal amount, not on accumulated interest.

Simple interest is different from compound interest. With simple interest, you earn the same amount each period on the original principal only.

Simple vs Compound Interest

The key difference is that compound interest earns interest on interest, while simple interest only earns on the principal.

Simple Interest

Interest only on principal. Same amount each period. Formula: I = P×r×t

Compound Interest

Interest on principal + accumulated interest. Formula: A = P(1+r/n)^(nt)

Advantages

Simple: predictable, easy to understand. Compound: faster growth over time.

Use Cases

Simple: short-term loans, savings bonds. Compound: investments, long-term savings.

Example: $1,000 at 5% for 5 years. Simple Interest = 1000 × 0.05 × 5 = $250. Total Amount = $1,250.

Applications

Savings Accounts Bonds Loans Investments Certificates

Frequently Asked Questions

What is simple interest?
Simple interest is calculated only on the principal amount. It does not compound - interest is earned only on the original investment, not on accumulated interest.
Simple vs compound interest?
Simple interest: I = P×r×t. Compound interest: A = P(1+r/n)^(nt). Compound earns interest on interest, so it grows faster over time.
How to calculate simple interest?
Simple Interest = Principal × Rate × Time. I = P × r × t. Total Amount = Principal + Interest.
When to use simple interest?
Simple interest is used for short-term loans, savings accounts, bonds, and certain types of investments. It provides predictable returns.

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