Simple Interest Calculator
By Hesaplayıcı
The simple interest calculator finds the final amount and the total interest when interest applies to the principal only. Enter the principal, the interest rate, the period of the rate and the term. Each year earns the same interest, because interest does not earn interest. The calculator shows every step and yearly and monthly balances.
Worked example: 10,000 at 10% a year for 5 years
Final amount
15,000
- Total interest
- 5,000
- Nominal annual rate
- 10.00%
- Effective annual rate
- 10.00%
- Term
- 5 years
Step by step
Nominal annual rate
r = rate × periods per year
r = 10% × 1 = 10.00%
Term
t = years + months/12 + weeks/52 + days/365
t = 5 + 0/12 + 0/52 + 0/365 = 5 years
Final amount
A = P × (1 + r × t)
A = 10,000 × (1 + 10% × 5) = 15,000
How to use
- Enter the principal.
- Enter the interest rate and choose its period: yearly, monthly, weekly or daily.
- Enter the Term and choose its unit: years, months, weeks or days.
- Press Calculate.
Formula
Simple interest uses A = P × (1 + r × t). A is the final amount, P the principal, r the annual rate as a decimal and t the term in years. The total interest is A − P, which is P × r × t.
A monthly rate is multiplied by 12, a weekly rate by 52 and a daily rate by 365 to get the annual rate.
Worked example
The worked example on this page runs the calculator’s first example step by step: the annual rate, the term in years and the final amount. When you calculate with your own values, the same steps appear in the result.
Limits
The calculator does not deduct tax, withholding or fees; it shows gross interest. For interest that earns interest, use the compound interest calculator. The rate stays the same for the whole term.
Frequently Asked Questions
What is simple interest?
Simple interest is calculated on the principal only. Interest does not earn interest, so every year earns the same amount.
How is simple interest calculated?
Simple interest uses the formula A = P × (1 + r × t), where A is the final amount, P is the principal, r is the annual interest rate as a decimal and t is the time in years. The total interest is P × r × t.
How is a monthly rate converted to a yearly rate?
A monthly rate is multiplied by 12. For example, 1% a month equals a nominal 12% a year. A weekly rate is multiplied by 52 and a daily rate by 365.
Calculation rules
- Simple interest applies to the principal only: A = P × (1 + r × t).
- A monthly rate is multiplied by 12, a weekly rate by 52 and a daily rate by 365 to get the nominal annual rate.
- In the term, 1 month is 1/12 year, 1 week is 1/52 year and 1 day is 1/365 year. The term is at most 100 years.
- Results are not rounded. The monthly breakdown has at most 1,200 rows.