Deposit Interest Calculator
Calculate the gross interest return on your time deposit, 15% withholding tax and net earnings using simple or compound interest.
The Interest the Bank Advertises vs. What You Actually Receive
The most common mistake in deposit interest calculations is assuming the gross rate advertised by the bank equals the actual return. In Turkey, individual time deposits are subject to 15% withholding tax deducted at source. For a 100,000 ₺ deposit at 45% annual interest for 90 days, the gross earnings are approximately 11,096 ₺, while the net amount you receive is approximately 9,432 ₺. This tool shows the full picture.
What Is the Deposit Interest Calculator and Why Do You Need It?
A time deposit is a savings instrument where money deposited in a bank for a set period is returned with interest at the end of the term. The calculator takes the annual interest rate banks typically advertise, applies it to the number of days and principal amount to compute gross interest, then deducts 15% withholding tax to show net earnings and the effective annual return.
For short-term deposits (32 or 90 days) the effective annual return appears lower than the bank's stated annual rate — because only that period's earnings are annualised and the compounding effect is not fully reflected.
How to Use It? Step by Step
Required Inputs
- Principal amount (₺)
- Annual interest rate (%)
- Term (in days; e.g. 32, 90, 180, 365)
- Interest type: simple or compound
Formula / Logic
Simple interest: gross earnings = Principal × (Annual Rate / 365) × Number of Days. Compound interest: gross earnings = Principal × [(1 + r)^(days/365) − 1]; in this method earned interest is periodically added to the principal, yielding a higher total return. In both cases, 15% of gross interest is deducted as withholding tax.
Example Scenario Table
| Scenario | Gross Interest | Withholding (15%) | Net Interest |
|---|---|---|---|
| 100,000 ₺ — 45% annual — 90 days (simple) | ≈ 11,096 ₺ | ≈ 1,664 ₺ | ≈ 9,432 ₺ |
| 250,000 ₺ — 50% annual — 180 days (simple) | ≈ 61,644 ₺ | ≈ 9,247 ₺ | ≈ 52,397 ₺ |
| 500,000 ₺ — 40% annual — 365 days (compound) | ≈ 200,000 ₺ | ≈ 30,000 ₺ | ≈ 170,000 ₺ |
| 50,000 ₺ — 45% annual — 32 days (simple) | ≈ 1,973 ₺ | ≈ 296 ₺ | ≈ 1,677 ₺ |
* Values in the table are approximate calculation results.
This tool is for informational purposes only. For precise results, consult a professional or financial advisor.
How to Interpret the Results?
The tool gives four key outputs: gross interest, withholding tax, net interest and effective annual return. Net interest is the amount you actually receive — compare this figure to the inflation rate to assess whether real return is positive or negative.
Effective annual return lets you correctly compare deposits with different terms. Look at this rate to see what a 90-day versus 365-day deposit actually yields on an annual basis. For short-term rolling deposits, the compounding effect can bring effective return close to the bank's stated annual rate.
Tips for Accurate Results
- Banks generally advertise the annual simple interest rate. Use the compound interest option only when the bank explicitly states it.
- Withholding tax is fixed at 15%; however, some government bond instruments may have a different rate. This calculator only handles standard deposits.
- To see whether your net return keeps up with inflation, also use the inflation calculator.
- When entering the term in days, checking with your bank is best; some banks offer standard terms such as 30, 60, 90, 180, 270, 365 days, while others also offer 32-day options.