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Enter your principal, annual interest rate, and term to quickly calculate total interest and total balance using simple or compound interest.
Enter the interest rate value and select the rate period (annual, monthly, or daily) on the right.
Simple Interest: Interest is calculated only on the principal amount, without compounding.
Please enter principal, interest rate, and term to calculate interest.
Overview
Understand what the tool solves, how it works, and the boundaries of its data.
Enter an initial principal, a rate, its period (annual, monthly, or daily), a term (years, months, or days), and simple or compound interest. Results include interest, total balance, rate periods, and a model-based effective annual rate. The amount can use any currency or consistent unit; no currency conversion or symbol is applied.
Let P be principal, r the selected-period rate as a decimal, and n the number of periods. Simple interest is I = P × r × n; total is P + I. Compound total is P × (1 + r)n; interest is total minus P. The calculator treats a year as 12 months or 365 days; annual, monthly, and daily rate periods mean 1, 12, and 365 periods per year. Period counts may be fractional when units do not align.
Enter 4.5 for 4.5%, not 0.045. With a daily rate, enter the daily percentage; an annual rate is not automatically divided into daily rates. The effective annual rate for compounding applies the selected rate over the model’s periods per year.
Guide
Follow the workflow and verify inputs and outputs with practical examples.
Use a positive starting amount and nonnegative rate. Type the rate as a percentage number. Keep the amount unit consistent; no currency is selected or converted.
Choose annual, monthly, or daily for the rate, then years, months, or days for the term. A monthly rate means the entered percentage applies per month.
Simple interest applies the rate to the original principal. Compound interest adds each period’s interest to the balance before the next period.
Review interest, total balance, period count, and effective annual rate. Money values display to two decimal places.
Example: 10,000 at 4% annual interest for 2 years gives simple interest of 800 and total 10,800. Annual compounding gives interest of 816 and total 10,816, in the same units as the principal.
Use cases
See how the tool fits into real work and everyday tasks.
Use one starting deposit and a stated rate to see how simple and compound models differ over the same term. Keep units identical when comparing.
For a balance due in one payment under a fixed-rate assumption, estimate interest and total, then compare the assumptions with the account or loan agreement.
Enter offers separately using each stated rate period and term. First check whether fees, contributions, withdrawals, or scheduled payments are included.
Q&A
Find concise answers to common questions and confusing cases.
No. The entered percentage uses the selected rate period. Convert or confirm the quoted rate before entering it.
No. The model does not reduce the balance with scheduled payments or add fees, so it cannot produce a payment schedule.
No. The displayed rate reflects the interest and compounding model. APR can include lender fees and follows required disclosure methods.
A contract may use actual calendar days, changing balances, payment dates, fees, or different rounding. This calculator uses 12 months and 365 days for unit conversion and a single fixed principal.
Notes
Review scope, result limitations, and important precautions before use.
This is an estimate for one principal at a fixed rate under a simple or compound model. It does not model deposits, withdrawals, installment amortization, daily changing balances, fees, taxes, penalties, or institution-specific day-count and rounding. Do not treat it as a lender’s APR disclosure: APR includes applicable fees and may use a required cash-flow method. Check signed terms and payment schedules before making a financial decision. This is not financial advice.
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