Scenario 1
Savings account
$10,000 at 5% for 3 years → simple interest: $1,500 | compound: $1,608. Compound earns $108 more.
Trusted by freelancers and business owners
Interest Calculator
See exactly how interest grows your savings — or adds to your debt.
Adjust your inputs
Results update instantly as you type or drag.
1 – 10,000,000
$
Starting amount — what you save, invest, or borrow
0.0 – 100
%
0.1 – 50
Quick insights
Simple interest
$1,500
Final balance (compound)
$11,615
Quick answer
What is the difference between simple and compound interest?
Simple interest is calculated only on the principal. Compound interest is calculated on the principal plus accumulated interest — so it grows faster over time.
How it works
From inputs to result in four steps
A quick walkthrough of what this calculator does behind the scenes.
- 1
Enter your principal — the starting amount.
- 2
Set the annual interest rate.
- 3
Choose the time period in years.
- 4
See simple interest, compound interest, and final balance instantly.
Formula
The math behind the number
No black box — here's exactly how the result is computed.
Simple: I = P × r × t Compound: A = P × (1 + r/n)^(n×t)
With compound interest, your interest earns interest — that's why it grows faster the longer you wait.
Examples
Real-world scenarios
See how the numbers play out for typical use cases.
Scenario 2
Long-term investment
$10,000 at 7% for 10 years → simple: $7,000 | compound: $9,671. Compound earns $2,671 more.
Scenario 3
Credit card debt
$5,000 at 20% for 2 years → compound interest: $2,430. The cost of carrying debt is steep.
Related
Pair this with
Other calculators that work well alongside this one.
Business
Loan Calculator
Calculate your monthly loan payment, total interest paid, and total repayment amount for any loan.
Open calculatorBusiness
Profit Margin Calculator
Calculate gross profit, profit margin, and markup from your revenue and costs.
Open calculatorBusiness
Break-even Calculator
Find the number of units (or revenue) you need to sell to cover your fixed costs.
Open calculator