Buy Now Pay Later True Cost Calculator

Last updated July 2, 2026

Buy Now Pay Later services — offered by companies like Affirm, Klarna, Afterpay, and others at point of sale — present as interest-free installment payment options, but the true cost varies enormously depending on the specific program and whether payment terms are met. Genuine 0 percent BNPL programs charge no interest when payments are made on schedule, making them a legitimate short-term financing option for borrowers who would otherwise charge a purchase to a high-APR credit card. The cost comes from fees charged to the retailer and built into the product price — a subsidy that consumers pay indirectly — and from penalty rates and fees when payments are missed.

The more expensive BNPL products — particularly those offered for larger purchases over longer terms — frequently carry interest rates of 15 to 36 percent APR, disclosed in percentage terms that many consumers don't translate to dollar amounts before accepting. A $1,200 purchase financed over 12 months at 24 percent APR costs $163 in interest — the equivalent of adding 13.6 percent to the purchase price. The consumer Financial Protection Bureau's 2022 report on BNPL found that borrowers who use these services frequently are more likely to carry revolving credit card debt, overdraft bank accounts, and carry delinquencies — suggesting that BNPL often adds to total debt burden rather than replacing it. The true cost calculation requires knowing the actual APR, not just the number and size of payments.

For any BNPL service, the key cost question is whether the APR is truly 0 percent or whether interest accrues on the purchase price. For 0 percent offers, ensure you can make every payment on schedule — the penalty terms for missed payments often include retroactive interest at high rates for the full purchase amount. Calculate the total dollar cost, not just the monthly installment, and compare that to paying with savings or a lower-rate credit card.