How do I use the Simple Interest Calculator?

Enter the required values, then calculate. The Simple Interest Calculator shows results, formulas, and step-by-step work when available. No account is required.

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How it works

Simple interest is computed on the original principal only. It does not compound. The amount due is principal plus interest.

I = P r t · A = P + I · P = A / (1 + r t)

When to use

Use this tool when you need to: {principal} at 3% for 10 years earns {interest}. Use compound interest when earnings are reinvested.

How to use this tool

Enter your values in the fields above.
Review the formula and any mode options for your problem.
Read the result and the step-by-step solution.

{principal} at 3% for 10 years earns {interest}. Use compound interest when earnings are reinvested.

Frequently asked questions

What is the Simple Interest Calculator?: Simple interest is computed on the original principal only. It does not compound. The amount due is principal plus interest.
How do I use the Simple Interest Calculator?: Enter the required values, then calculate. The Simple Interest Calculator shows results, formulas, and step-by-step work when available. No account is required.
What formula does the Simple Interest Calculator use?: I = P r t · A = P + I · P = A / (1 + r t)

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Simple Interest Calculator

Enter principal, rate, and term to get total interest and the end balance.

How it works

What simple interest is

Interest is the cost of borrowing, or the return for lending. Simple interest is a fixed percentage of the original principal only. Later interest does not depend on interest already earned. Short-term loans and some coupon payments are quoted this way; most savings accounts and credit cards are not.

I = Prt and I = Prn

With an annual rate, I = P × r × t, where t is years (months count as twelfths of a year). With a rate per period, I = P × r × n, where n is the number of periods — for a monthly rate, n is the number of months. End balance is A = P + I.

Solve for any piece

The same formula rearranges. Principal is P = A / (1 + r t). Term is t = I / (P r). Rate is r = I / (P t). Switch tabs to hide the unknown. A zero rate means the end balance equals the principal; a zero rate cannot determine a unique term.

Simple vs compound interest

Compound interest charges interest on interest, so the balance grows faster. $10,000 at 5% simple for five years costs $2,500 of interest. Monthly compounding on the same quote costs more. Use this tool when the contract is simple interest. Convert quoted compound rates on the Compound Interest calculator, and grow a principal with Future Value.

How it works

Simple interest is computed on the original principal only. It does not compound. The amount due is principal plus interest.

I = P r t · A = P + I · P = A / (1 + r t)

When to use

Use this tool when you need to: {principal} at 3% for 10 years earns {interest}. Use compound interest when earnings are reinvested.

How to use this tool

Enter your values in the fields above.
Review the formula and any mode options for your problem.
Read the result and the step-by-step solution.

{principal} at 3% for 10 years earns {interest}. Use compound interest when earnings are reinvested.

Frequently asked questions

What is the Simple Interest Calculator?: Simple interest is computed on the original principal only. It does not compound. The amount due is principal plus interest.
How do I use the Simple Interest Calculator?: Enter the required values, then calculate. The Simple Interest Calculator shows results, formulas, and step-by-step work when available. No account is required.
What formula does the Simple Interest Calculator use?: I = P r t · A = P + I · P = A / (1 + r t)

Browse categories