Simple Interest Calculator
Enter the principal, the rate and the time to get the interest, the total and a period-by-period table from the textbook simple interest formula (I = P × r × t). The rate can be yearly, monthly or daily, and the year 360 or 365 days.
- Working50,000 × 15 × 2 ÷ 100 = 15,000
- Principal50,000.00 ₺
- Time in years2
- Total (P + I)65,000.00 ₺
Interest by year
How it is calculated
With simple interest only the principal earns interest: the same amount is added each period, so interest grows in proportion to time. With compound interest each period’s interest joins the principal and earns interest too. This page is a teaching tool that works the school formula step by step; it leaves out tax, fees and bank practice. For a Turkish term deposit after withholding tax use the deposit interest calculator, and to compare simple and compound interest with the effective yearly rate use the finance interest calculator.
I = P × r × t ÷ 100I: interest · P: principal · r: yearly rate (%) · t: time in years (Turkish textbooks write F = A × n × t ÷ 100). For months divide by 1,200, for days by 36,000 (360-day year) or 36,500 (365 days).- Put the rate and the time in the same unit: a yearly rate and years, a monthly rate and months, or a daily rate and days.
- Multiply principal, rate and time and divide by 100: that is the interest.
- The total is principal plus interest: P + I = P × (1 + r × t).
- With simple interest every period earns the same; interest earns no interest.
Example
₺50,000 at 15% a year for 2 years: I = 50,000 × 15 × 2 ÷ 100 = ₺15,000, a total of ₺65,000. For 90 days the same money earns 50,000 × 15 × 90 ÷ 36,500 ≈ ₺1,849.32 on a 365-day year, or 50,000 × 15 × 90 ÷ 36,000 = ₺1,875 on a 360-day year.
Frequently asked questions
What is the difference between simple and compound interest?
Simple interest is always worked on the original principal; compound interest adds earned interest to it. ₺100,000 at 15% a year for 10 years grows to ₺250,000 with simple interest and about ₺404,555.77 compounded yearly. The gap widens with time.
Is a year 360 or 365 days?
Both are day-count bases in use; the contract (or the problem itself) says which applies. With a 365-day year the interest for a number of days is P × r × days ÷ 36,500; on the 360-day “commercial year” basis it is P × r × days ÷ 36,000, which gives slightly more interest for the same rate and time. Choose either when you enter the time in days.
How do I turn a monthly rate into a yearly one?
With simple interest, multiply by 12: 3% a month is 36% a year. If the interest is added to the principal every month (compounding), the yearly equivalent is (1.03)^12 − 1 ≈ 42.58%.
How do I find the rate or the time instead?
Rearrange the formula: r = I × 100 ÷ (P × t) and t = I × 100 ÷ (P × r). If ₺10,000 earned ₺4,500 in 3 years, the yearly rate was 4,500 × 100 ÷ (10,000 × 3) = 15%.
Is the result after tax?
No, it is gross; no tax or fees are taken off. For the net return on a time deposit, use the deposit interest calculator.