Credit Card Interest Calculator

Credit cards charge interest on any balance you don't pay in full by the due date. Rates are high — often 30–48% per year in India — and the cost compounds quickly. The design is deliberately generous at the front: buy today, pay later, and if you clear the statement in full you pay nothing. The trap is that the moment you carry a balance, that same card becomes one of the most expensive loans available.

How the interest is charged

Most cards charge interest daily but post it monthly. The daily rate is:

Daily rate = annual rate ÷ 365

Your balance each day earns that fraction, and at month end it is added to your balance. From then on, you pay interest on the interest — that's compounding.

The quick monthly estimate is:

Monthly interest = balance × (annual rate ÷ 12)

Example

A ₹50,000 balance at 36% per year:

Monthly interest = 50,000 × 0.36 ÷ 12 = ₹1,500/month

If you pay ₹5,000/month, each month the interest is added, then your payment is deducted:

Month 1: 50,000 + 1,500 − 5,000 = ₹46,500
Month 2: 46,500 + 1,395 − 5,000 = ₹42,895
... and so on until zero.

Run it through the calculator and the balance clears in about 13 months, having cost roughly ₹10,338 in interest. A ₹50,000 purchase paid over thirteen months ends up costing about ₹60,338 — a 20% mark-up that the EMI-style "3% per month" marketing language never shows you.

The interest-free window — and how you lose it

Most cards give a grace period of around 45–50 days from purchase to payment, provided you had no outstanding balance in the previous billing cycle. Once you carry a balance, the grace period typically stops applying — new purchases start accruing interest immediately from the transaction date. Two consequences: paying "only the minimum" extends the interest-free window to nothing, and clearing last month's statement while buying this month creates a balance that is never fully paid off.

The trap

If your payment is less than the monthly interest, the balance never shrinks — you pay interest forever. Your card's "minimum due" is often exactly this kind of payment. Paying it keeps you trapped in debt. On the example above, a minimum payment of 5% of the balance (about ₹2,250) hovers above the ₹1,500 monthly interest, so the debt crawls for years.

Getting out faster

• Pay in full and on time — the only way to owe zero interest.
• Snowball order: tackle the smallest card first for motivation.
• Avalanche order: tackle the highest-rate card first to save the most money — usually the better financial choice.
• Balance transfer to a lower-rate card can help, but transfer fees (typically 2–3%) only beat a 36% rate if you clear the balance quickly.

Pay the full statement balance by the due date and you pay zero interest. If you can't, pay as much as possible and treat the card as closed.