Calculate buy now pay later payments for a Pay in 4 or custom plan, with total fees, total cost and estimated APR, or find the most you can spend.
Buy Now Pay Later Formula
With a down payment and equal later installments, the scheduled installment is:
M = (P - D) / n + f
Total purchase cost is:
For an APR estimate, the periodic rate r solves the present-value equation:
Variables:
- P is the purchase price
- D is the checkout down payment
- n is the number of later installments
- f is the fee added to each installment
- C is total cost including modeled fees
The calculator reports both a nominal annualized rate and an effective annual rate based on the chosen weekly, biweekly, or monthly frequency. Budget mode works backward from a maximum installment after subtracting per-payment and expected late fees.
BNPL Fee Reference
A plan advertised as interest-free can still have a borrowing cost when mandatory or realized fees are included.
| Plan feature | Effect on installment | Effect on total cost | APR effect |
|---|---|---|---|
| Larger down payment | Lowers later installments | Does not change cash price | Can change amount financed |
| Upfront fee | No change to later installment | Raises cost immediately | Often raises APR sharply |
| Per-installment fee | Raises each installment | Raises cost with every payment | Raises APR |
| Late fee | Usually added to a payment | Raises total cost | Raises realized borrowing cost |
Example Problems
Example 1: Four-installment purchase with fees.
A $1,200 purchase has no down payment, four monthly installments, a $20 upfront fee, and a $5 fee per installment. Each later installment is $1,200 ÷ 4 + $5 = $305. Total fees are $40 and total cost is $1,240. The calculator also solves for the rate implied by receiving $1,180 of net financed value and making the scheduled payments.
Example 2: Find an affordable purchase price.
You can pay $150 every two weeks for four installments, with a $3 fee in each payment and no late fees. The amount available for principal is ($150 − $3) × 4 = $588. Add any checkout down payment to estimate the maximum purchase price.
Frequently Asked Questions
Can a zero-interest BNPL plan have a nonzero APR?
Yes, when fees that are part of obtaining or using the credit reduce the net value received or increase required payments. Fee classification and disclosure rules vary by product.
Why does payment frequency matter?
The same fee charged over fewer days has a larger annualized effect. Weekly and biweekly plans complete more quickly than monthly plans with the same number of installments.
Should optional late fees be included?
Include them when estimating your likely realized cost, but distinguish that personal scenario from the provider’s required credit disclosure. Avoiding late fees can materially reduce the total cost.
