This calculator shows what it costs to convert a credit card purchase you made at full price, and which has not yet appeared on a statement, into an installment plan. It applies the maximum contractual interest rates published by Turkey's central bank (TCMB) at the tier matching your statement balance, adds 15% BSMV and 15% KKDF on the interest, and produces a month-by-month payment plan.
What this calculator works out
The tool models a single full-price card transaction being spread over installments after the fact. It takes the transaction amount, the term you choose and the monthly rate to apply, then separates each installment into principal, interest, BSMV and KKDF so the total cost is visible rather than implied.
- Spreads the cash transaction amount over the term you enter and computes the monthly installment.
- Takes the monthly rate from the applicable TCMB maximum tier, or lets you enter your bank's own rate.
- Calculates 15% BSMV and 15% KKDF on the interest and builds them into the installment.
- Reports total repayment, total interest, tax and fund amounts and the cost ratio separately.
- Lists the month-by-month plan together with the remaining balance.
This tool is for a purchase where you did not choose installments at checkout — the transaction went through at full price. If you did choose installments at checkout and now want to increase the number of them, use the credit card additional installment calculator instead.
Four operations that look alike — which one is this?
There are four distinct installment operations on a credit card. They look similar from the outside, but they are different products under different rate ceilings. Picking the wrong one does not shift the result by a few lira — it changes the entire regime being applied.
- Choosing installments at the point of purchase: you select 3, 6 or 9 installments at the till or on the payment screen. This is usually interest-free under a merchant campaign. This tool does not calculate it.
- Increasing the installment count on an already-installmented transaction: spreading a purchase currently split over 3 installments across 8. Use the credit card additional installment tool for that.
- Converting a full-price transaction into installments afterwards: taking a purchase that went through as a single payment and splitting it into installments after the fact. THIS IS WHAT THIS TOOL CALCULATES.
- Restructuring card debt: binding the whole of your card debt into a new payment plan. That is a different regime, capped by the TCMB reference rate of 3.11% per month. This tool does not calculate it.
You enter a single purchase that went through your card at full price as one payment, with a settled amount. The tool spreads that amount over the term you select. What is modelled is one transaction — not your total card debt, not your other spending, and not the sum of several transactions.
The transaction amount is the size of the single purchase you are installmenting, and it becomes the principal of the plan. The card statement balance is your card's total debt at the statement date, and it is used only to select the TCMB rate tier. They are different quantities, and the tool never substitutes one for the other.
How the interest rate is determined
Credit card interest in Turkey is capped. TCMB publishes the maximum contractual and default rates that may be applied to card transactions, and no bank may exceed them. Since 1 January 2026 the maximum contractual rate is not a single figure but a tier that depends on the card's statement balance.
- Cards with a statement balance below 30,000 TL: maximum 3.25% per month.
- Statement balance between 30,000 TL and 180,000 TL: 3.75%.
- Statement balance above 180,000 TL: 4.25%.
- Cash advances: 4.25%.
The calculator selects the correct tier from the statement balance you enter and shows which tier it applied. The statement balance and the transaction amount are different figures, so the balance is required when the TCMB rate is selected and the transaction amount is never used in its place. Your bank may apply a rate below the ceiling, in which case you can enter it manually — and if you also enter the statement balance, your rate is checked against the legal ceiling.
If the rate you enter manually exceeds the TCMB maximum for your card's balance tier, the calculator does not produce a plan and says so explicitly. A bank cannot lawfully charge a contractual rate above the published ceiling.
How BSMV and KKDF affect the installment
Interest is not the whole cost. BSMV (banking and insurance transactions tax) at 15% and KKDF (resource utilisation support fund) at 15% are calculated on the interest amount. Neither is charged on the principal — only on the interest.
In practice this means that when 100 TL of interest is calculated, 130 TL is what you pay. The calculator does not leave this load outside the installment and bolt it onto the total at the end; it is built into each installment, so the monthly figure shown is the figure you actually pay.
Commercial loans are exempt from KKDF and carry BSMV at 5%. Personal credit card interest is taxed at the consumer rates. The same nominal rate is therefore materially more expensive on a personal card than on commercial credit.
How many installments are allowed?
The maximum installment count is not a single number. Under article 26 of BDDK's Regulation on Bank Cards and Credit Cards and the Credit Card Installment Limits and Prohibitions table, the ceiling depends on the transaction category. That is why the calculator has a transaction category field, and why it applies the limit belonging to the category you select.
- General transactions: a ceiling of 12 months.
- Domestic travel and accommodation: 18 months.
- Health, furniture and white goods: 9 months.
- Refurbished mobile phones 12 months, tablets 6, club memberships 6.
- Electronics 4 months; non-bullion jewelry and travel to the TRNC 3 months.
- Telecommunications, fuel, food and catering, alcoholic beverages, cosmetics, office supplies, direct marketing, purchases made abroad, foreign travel other than the TRNC, printed and bullion jewelry, and gift cards: installments are prohibited entirely.
If you do not select a transaction category the calculation still runs, but the result declares that category-specific installment eligibility and the maximum count have NOT been verified. In that state 12 months is only a mathematical assumption, not a legally verified limit: the maximum for your own category may be shorter, or installments may be prohibited outright. When you select a prohibited category the calculator produces no installment plan at all and states why.
Reading the result
- Monthly installment: what you pay each month, tax and fund included.
- Total repayment: the sum of every installment over the term.
- Total interest, BSMV and KKDF: the three components of the cost, separately.
- Cost ratio: the extra burden expressed as a percentage of the transaction amount.
- Installment plan: payment, principal, interest-plus-tax and remaining balance for each month.
The cost ratio is the quickest way to compare terms. A longer term lowers the monthly installment but raises the cost ratio; running two terms through the calculator shows that trade-off directly.
The results are estimates based on the assumptions you entered. Your bank may decline the request, apply a different rate below the ceiling, or add a separate transaction fee. Rely on your card statement and your bank for the binding figures.
Frequently Asked Questions
Can I convert a purchase I already paid for in full into installments?
Most Turkish banks offer post-transaction installment conversion for purchases that have not yet entered a statement period. It is a product the bank offers rather than a right you hold — acceptance depends on the bank and on which goods or services group the transaction belongs to.
Can the conversion be interest-free?
Installments chosen at checkout under a merchant campaign are usually interest-free. Converting a transaction afterwards is a financing operation and as a rule carries interest plus BSMV and KKDF. If your bank offers a reduced or zero rate under a campaign, enter that rate manually to see the result.
Which interest rate does the calculator use?
By default it uses the maximum contractual rate published by TCMB, taken from the tier that matches your card's statement balance. That is the legal ceiling your bank may apply; your actual rate may be lower and can be entered manually.
Why does it ask for the statement balance?
Because since 2026 the maximum contractual rate varies with the statement balance: different ceilings apply below 30,000 TL, from 30,000 up to and including 180,000 TL, and above 180,000 TL. The balance is what selects the right tier, and it is a different figure from the transaction amount — so the tool asks for it rather than substituting the amount.
How do I see the true cost of converting?
Look at the cost ratio row. It divides the combined interest, BSMV and KKDF by the transaction amount, summarising in a single number how much extra the installment plan costs you.