BNPL Total Cost Calculator
Klarna, Affirm, and Afterpay each show their own numbers in their own app. Add the plans you're considering and line them up side by side: effective APR, total cost, and what you'll actually pay per installment. Nothing uploaded.
Cheapest Plan
Plan Comparison ?
| Provider | Total cost | Per installment | Effective APR |
|---|
Add a plan to see your comparison.
Learn more: what "interest-free" BNPL actually costs
How the effective APR is worked out here
The calculator turns a plan's disclosed fee into an annual rate with one formula: the fee divided by the purchase price, then scaled by 52 weeks over the plan length in weeks. If a plan charges no fee, the effective APR is 0% no matter how the payments are arranged.
Plan length does most of the work. A $24 fee on a $300 purchase reads 8.0% when the plan runs a full 52 weeks. Put the same $24 fee on a 12-week plan and the tool shows 34.7%, because the identical dollar cost is being annualized over a quarter of the time.
The figure has two limits worth knowing. It is not an amortized rate, since the formula treats the whole purchase price as outstanding for the entire plan while you actually pay it down installment by installment. It also ignores anything a provider charges later, so use it as a yardstick for comparing plans against each other rather than as a legal APR disclosure.
Installments and plan length are separate inputs
The installment count only changes the per-payment figure, which is the total cost divided by the number of installments. The week count only feeds the APR. Keeping them separate is what lets you model the common pattern of four payments spread across six weeks, where money comes out every two weeks.
A $300 purchase with no fee, split four ways over six weeks, comes to $300 total and $75.00 a payment at 0.0% effective APR. The same $300 with a $24 fee over 12 installments totals $324 and costs $27.00 a payment.
What the ranking uses, and what it leaves out
The comparison table sorts cheapest total cost first, and the "Cheapest" badge follows that dollar total rather than the APR column. For one purchase where every plan covers the same item, total cost is the honest measure. APR earns its place when the plans you are weighing run for different lengths.
Only the fees you type in are modeled. Late charges, deferred interest that starts after a promotional window, refund handling, and credit bureau reporting all sit outside the math, so a 0.0% row means the plan has no disclosed upfront fee and nothing more than that.
Rows are also independent of each other. Nothing is summed across plans, so if you are carrying several at once, add up the per-installment column yourself to see what leaves your account in a given cycle.
FAQ
Why does the same fee show a bigger APR on a shorter plan?
Because APR is annualized. A $20 fee on a $200 purchase shows 86.7% across a 6-week plan and 43.3% across a 12-week one, exactly half, since the fee is being stretched over twice the time. That is the gap a flat dollar figure hides.
Does a 0.0% effective APR mean the plan is free?
It means there is no upfront fee in what you entered. Missed-payment charges and any interest that starts after a promotional period are not part of this calculation, so a 0.0% row is only accurate for someone who pays every installment on time.
Should I pick the lowest total cost or the lowest APR?
Total cost, when you are buying one thing and every plan covers the same price. That is the dollar amount actually leaving your account, and it is what the table ranks by. Use the APR column to compare plans whose lengths or fee structures differ.