U.S. · buy now, pay later
Buy now, pay later true cost calculator.
Add up the checkout payment, installments, interest and late fees for a pay-in-four plan or a financed purchase.
A typical pay-in-four plan charges no interest: 25% at checkout and three more payments two weeks apart. Its cost shows up as fees: a $400 purchase with one $7 late fee costs $407. A financed plan is different: $1,200 at 30% APR over 12 months costs $1,403.81, or $203.81 more than the price.
Your numbers
Result
How this is calculated
For pay-in-four, the calculator splits the price into a 25% down payment and three equal payments, adds interest of zero, and adds any late fees you enter. For an installment plan it uses the standard level-payment formula at your APR: payment = price × r ÷ (1 − (1 + r)−n), where r is APR divided by 1,200 and n is the number of months. Total cost is the price plus interest plus late fees.
The CFPB describes the pay-in-four product as typically a four-installment, no-interest loan with a 25% down payment and the remaining three installments due at two-week intervals (The Buy Now, Pay Later Market, December 2025). In the same report, four lenders that charge late fees assessed one on 4.1% of loans in 2023, at an average of $9.99 per fee in inflation-adjusted dollars. Lenders that offer longer installment loans publish APR ranges and set your rate after an eligibility check: Affirm's site, for example, says 0% to 36% APR, checked on October 26, 2026.
Worked example
Pay in 4, $400 purchase, one late payment with a $7 fee. Down payment: $400 × 25% = $100. Three payments of $100 follow, two weeks apart. Interest is $0, the late fee is $7, so the total is $407, which is $7 (1.8%) over the sticker price.
Installments, $1,200 at 30% APR for 12 months. The monthly payment is $116.98, interest totals $203.81, and the total paid is $1,403.81, 17.0% over the price.
Limits of this estimate
It does not model returns, refunds, delayed first payments, promotional zero-interest installment offers with deferred interest, or fees other than the ones you type in. Always confirm the terms in your loan agreement.
Sources
Primary sources opened and checked on October 26, 2026. Figures are as published on that date and are not a prediction of your own terms.
Common mix-ups
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Often assumedPay in 4 never costs anything extra, because it is interest-free.
What the source saysThe CFPB describes pay-in-four as typically no-interest, but four lenders that charge late fees assessed one on 4.1% of loans in 2023, averaging $9.99 per fee in inflation-adjusted dollars. [1]
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Often assumedEvery buy now, pay later offer is a four-payment, no-interest plan.
What the source saysThe CFPB report covers only pay-in-four products and notes that most firms offering them also offer other point-of-sale financing, such as installment loans, which its data does not include. [1]
Checked against these sources on .
Frequently asked questions
Does buy now, pay later charge interest?
The pay-in-four product described by the CFPB is typically a no-interest loan. Longer installment loans offered by the same companies can carry interest: Affirm publishes a 0% to 36% APR range and sets your rate after an eligibility check.
What does pay in 4 actually cost?
Usually the price itself, split into a 25% down payment and three more payments two weeks apart. The extra cost comes from late fees and from spending more because the payments feel small.
How common are BNPL late fees?
For four lenders that charge late fees, 4.1% of loans were assessed a late fee in 2023, down from 7.0% in 2019, at an average of $9.99 per fee assessed in inflation-adjusted dollars (CFPB, December 2025).
Is an installment plan with an APR the same as a credit card?
The arithmetic is different. An installment loan has a fixed payment and a set end date, so the interest is known up front. Use the credit card calculators to compare it with revolving debt.
How do I compare BNPL with a credit card?
Run this calculator for the BNPL cost, then run the credit card payoff calculator with your card APR for the same purchase and months. Compare the totals.
Not financial advice
This page is general information, not financial, legal or tax advice. Your loan, card or plan terms control and may differ from the examples. Confirm anything that matters with your lender, bank, insurer or a qualified adviser before you act. Everything runs in your browser; nothing you enter is sent anywhere.