Sri Lanka Credit Card Interest & Minimum Payment Calculator

Sri Lankan credit card issuers compute finance charges using the average daily balance method, as disclosed by the Central Bank of Sri Lanka's Financial Consumer Relations Department and the tariff schedules of Commercial Bank, Sampath, HNB, NDB, DFCC, and the state-owned BOC and People's Bank card portfolios. The method has three components — a periodic finance charge, a regulator-policed rate ceiling, and a per-cycle minimum payment formula — and this calculator runs all three so you can see them side by side.

Step 1 — Periodic finance charge

The daily periodic rate is APR ÷ 365. Multiply it by the average daily balance during the cycle and by the number of days in the cycle:I = B × (APR ÷ 365) × cycleDays. With no new transactions and no part-payment during the cycle, the average daily balance equals the opening balance. The calculator also exposes a compound-daily cross-check formula (1 + APR ÷ 365)^cycleDays − 1 for readers who want to verify against the bank's effective rate disclosure — the two methods differ by less than 0.4% at 28% APR over a 30-day cycle, well within rounding noise on a real statement.

Step 2 — Regulator cap

Under Banking Act Direction No. 02 of 2021 the Central Bank caps the maximum permissible interest rate on credit cards at 36% per annum. The calculator validates your input against this ceiling and shows an amber warning banner if your APR exceeds it — the most common reason this happens in practice is a forex-billed balance which the issuer prices at the cap but lists separately on the statement, so the warning is informational, not an error. The calculator still runs the projection with whatever rate you entered so you can see the real-world consequence.

Step 3 — Minimum payment formula

The standard minimum is the greater of a percentage of the statement balance (typically 5%, sometimes 3%) or a rupee floor (Rs 1,000 at most issuers, Rs 500 at a few promotional tiers). The calculator treats both as inputs because the regulator does not prescribe a single formula — each issuer publishes its own. The minimum is applied to the statement balance after the cycle's finance charge is added, matching the way it appears on a statement.

Step 4 — Payoff projection

The loop iterates one cycle at a time. Each cycle accrues interest on the opening balance, applies the payment from the chosen plan (minimum only, fixed amount, or pay in full), and carries the remainder into the next cycle. The loop terminates the cycle the closing balance hits zero; if the chosen payment is below the cycle interest, it terminates with a "never clears" warning. The minimum-only plan is the slowest path and the one most cardholders accidentally fall into when budgets get tight.

The minimum-payment trap

A useful mental model: the minimum-payment percent on Sri Lankan credit cards is set just high enough above the cycle interest that the balance does slowly fall, but only barely. On a 28% APR card with the 5% minimum policy, the per-cycle interest rate is about 2.3% and the minimum payment is about 5.1% of the post-interest balance — so principal reduction is roughly 2.8% per cycle while the balance is large, and the floor of Rs 1,000 kicks in once the balance drops under about Rs 20,000. This is the mathematical reason a Rs 100,000 balance on minimums takes the better part of a decade and costs more in interest than the original spend.

What this tool does not cover

Cash advances and ATM withdrawals use a different rate structure — no grace period plus a fixed handling fee — and balance transfers, EMI / instalment plans, and reward points have issuer-specific terms that are not captured by a single APR. Foreign-currency transactions add a 1–3% mark-up that this calculator does not model. For loans use the Sri Lanka loan EMI calculator and for personal-loan consolidation maths compare the EMI calculator against the minimum-only output here — if the EMI is less than the minimum, consolidation is usually the cheaper path.

Three scenarios with end-to-end maths. Plug each into the calculator above — the cycle-1 numbers should match to the rupee, and the totals should match within Rs 5 (rounding differences accumulate over long horizons).

• CBSL — Banking Act Directions (incl. credit card interest cap, Direction No. 02 of 2021)
• CBSL — Financial Consumer Relations Department
• Commercial Bank of Ceylon — Credit Card Terms & Conditions
• Sampath Bank — Credit Card Tariff Schedule
• HNB — Credit Card Terms (minimum payment and late fees)

The CBSL ceiling and major issuer tariff schedules were last cross-checked on 2026-05-16. Page reviewed every January and after any CBSL Direction amendment.