What is the 45-day interest-free period on credit cards and how can you use it smartly?

Most credit cards in India give users an interest-free period that can run up to 45 or even 50 days. This window exists because banks calculate interest only from the day a transaction is billed, not from the day you swipe the card. Each billing cycle has a fixed monthly date. Purchases made just after this date enjoy the longest interest-free runway, while transactions made closer to the bill-generation date get fewer days. The catch is simple but strict: the benefit vanishes the moment you fail to pay the entire outstanding amount by the due date. How the cycle actually works in practice

Imagine a billing cycle that runs from the fifth of one month to the fourth of the next. If you buy something on the sixth, it appears on the next month’s bill, giving you about 45 days before payment i