Financial

Simple Interest Calculator

Estimate non-compounded interest and final balance.

Inputs

Adjust the assumptions to match your scenario. Results update instantly.

PrincipalStarting amount of money before simple interest is applied.Annual rateAnnual simple interest rate used for the calculation.YearsLength of time that the principal stays invested or borrowed.

Results

Primary outputs and comparison insights are built from the current inputs.

Interest earned

$1,800.00

Total simple interest generated over the full term.

Final balance

$11,800.00

Principal plus the simple interest earned over the term.

Interest per year

$600.00

Average yearly interest at the selected simple rate.

How this calculator works

The Simple Interest Calculator helps you check short-term loans, invoice terms, and basic savings products that do not compound during the holding period. Enter principal, annual rate, and years to estimate interest earned, final balance, and interest per year. The calculator updates instantly and adds a comparison table plus chart so you can test the sensitivity of the result before you use it in a decision.

Quick guide

Jump straight to the section you need, then return to the calculator.

Inputs Outputs Assumptions Tips Formulas Examples Reference table Visual breakdown References

Inputs

Starting amount of money before simple interest is applied.
Annual simple interest rate used for the calculation.
Length of time that the principal stays invested or borrowed.

Outputs

Total simple interest generated over the full term.
Principal plus the simple interest earned over the term.
Average yearly interest at the selected simple rate.

Assumptions

Interest does not compound during the term.
The annual rate stays constant for the full period.

Tips

Use simple interest for notes, trade credit, and short loans.
If the product compounds monthly or daily, use a compound calculator instead.

Formula guide

Use these formulas to audit the output or explain it to someone else.

2 formulas

Simple Interest = Principal × Rate × Time

Final Balance = Principal + Simple Interest

Usage examples

Review a ready-made scenario, copy it, then tweak inputs to match your case.

Example

3 inputs3 outputs

Short loan estimate

Inputs

Example input Principal: $12,000.00
Example input Annual rate: 7%
Example input Years: 2

Outputs

Example result Interest earned: $1,680.00
Example result Final balance: $13,680.00
Example result Interest per year: $840.00

Simple interest is useful when the lender charges a flat annual rate without compounding inside the term.

Interest by annual rate

4 of 4 rows

Annual rate	Interest earned	Final balance
4%	$1,200.00	$11,200.00
6%	$1,800.00	$11,800.00
8%	$2,400.00	$12,400.00
10%	$3,000.00	$13,000.00

Use the scenario view to compare how rate changes total simple interest over the same time period.

Interest sensitivity

Highest: 10% ($3,000.00)Lowest: 4% ($1,200.00)

Sort

Annual rateInterest earned

Focus point

$1,200.00

Position

#1 of 4

Original order

Share of total

14.29%

Total: $8,400.00

PositiveNegative

Use the scenario view to compare how rate changes total simple interest over the same time period.

References

Basic finance formulas for simple interest
Consumer lending examples with non-compounded interest

FAQ

Common questions

What does the Simple Interest Calculator do?

What inputs do I need?

Typical inputs include Starting amount of money before simple interest is applied., Annual simple interest rate used for the calculation., Length of time that the principal stays invested or borrowed..

How are the results calculated?

We follow the formulas and assumptions outlined in the "How this calculator works" section. You will see outputs like Total simple interest generated over the full term., Principal plus the simple interest earned over the term., Average yearly interest at the selected simple rate..