The duration ladder: pick by months, not by product
The technique
Price the same ₹50,000 at each duration, then choose
People compare a card's monthly rate with a loan's annual rate and conclude nothing, because 3.5 and 14 are not in the same units. Put both on the same ₹50,000 for the same number of months and the comparison becomes arithmetic, and the arithmetic flips at a specific month.
Here is ₹50,000 by how long it will be outstanding. The card figures assume an illustrative 3.5 percent a month plus 18 percent GST on the interest. The loan figures assume an illustrative 14 percent reducing-balance rate and a 2 percent processing fee plus GST, which is ₹1,180 on ₹50,000 and is deducted before the money arrives.
| Money back in | On the card | As a loan | Instrument |
|---|---|---|---|
| Up to 45 days, cleared by the due date | ₹0 | ₹3,241 (six months at 14%) | Card |
| One cycle past the due date, then cleared | ₹2,065 | ₹3,241 | Card, if the balance then goes to zero |
| Three months, a third cleared each month | ₹4,130 | ₹3,241 | Loan, or card only with a dated paydown |
| Twelve months | ₹24,780 with the balance held flat | ₹5,052 (twelve months at 14%) | Loan, or card EMI conversion |
- The crossover is in the second month. One cycle on the card costs ₹2,065 and the shortest sensible loan costs ₹3,241 all in, so a single missed cycle with a certain clearance is still a card problem, not a loan problem
- By month three the card has cost ₹4,130 even with a third of the balance cleared every month, against ₹3,241 for a six-month loan whose EMI is fixed and whose interest falls every month. From here the loan is cheaper, and the gap widens with every month the money stays out
- The card's own arithmetic is what moves it: a flat ₹50,000 balance costs ₹2,065 every month it is carried, so after 2.45 months of flat balance the card has already cost what a 14 percent loan costs for a full year






