Sri Lanka: a capped rate and a 5% minimum
Sri Lanka is one of the few markets here where the regulator caps credit-card interest outright. The Central Bank of Sri Lanka sets a maximum rate on card balances, and the ceiling has sat around 28% in recent years. It is not a permanent number: the Central Bank reviews it and has moved it with policy rates, so check the current direction before trusting an older figure, and treat the 28% the calculator opens on as the recent norm rather than a fixed law.
Issuers typically require 5% of the balance a month, with the month's interest taken from within that payment and a flat floor of about Rs 1,000 on small balances. Against a capped rate the 5% works: at 28% a year the interest is a little over 2.3% a month, so most of the first payment still reaches the principal, which is why Sri Lankan minimum payments clear a card in years rather than the decades an American 1% minimum takes.
The cap applies to interest, not to the other charges on the account. Annual fees, late fees and cash-advance charges sit outside it and outside this calculator.