An extra payment option can bring an extra cost. Before adding buy now, pay later, ask what each completed order leaves after product costs, delivery, ads and the payment fee. Higher checkout revenue alone does not answer that question.
Stripe’s BNPL documentation explains the payment flow: customers pay over time while the merchant receives the purchase amount under the provider’s arrangements. That does not make the method free. Check the pricing for your country and payment method, plus your own agreement and settlement rules. The rates below are chosen examples, not quotes from a provider.
Start with one order
Take a $50 product order. Its product cost is $25, shipping and packing cost $5, and advertising cost $8. There is $12 left before the payment fee. Tax, refunds, overhead and owner pay are excluded from this simple comparison.
| Cost or result | Option A | Option B |
|---|---|---|
| Product revenue | $50.00 | $50.00 |
| Product, delivery and ad cost | $38.00 | $38.00 |
| Chosen payment fee | 3% + $0.30 | 6% + $0.30 |
| Payment fee on this order | $1.80 | $3.30 |
| Contribution after these costs | $10.20 | $8.70 |
The customer paid the same amount. The second payment option leaves $1.50 less on the order. For 100 otherwise identical orders, contribution falls from $1,020 to $870.
How many extra orders cover the difference?
Divide the contribution you want to preserve by the contribution per order under the alternative: $1,020 ÷ $8.70 = 117.24 orders. Since an order is a whole event, the store needs 118 orders in this example. That is 18 more completed orders than the original 100.
On a continuous-rate basis, $10.20 ÷ $8.70 − 1 is about 17.24%; a minimum threshold rounded up to two decimal places is 17.25%. Keep the whole-order target separate from that percentage. Neither calculation shows that offering BNPL will produce the extra orders.
Use the order profit calculator to compare your own costs. Enter sales of $5,000, 100 orders, product cost of $2,500 and ad spend of $800. Open other costs: set delivery to $500, fees to $180, refunds, recovered cost and return handling to zero. The result is $1,020. Compare it with $330 in fees to get $870. Check all the remaining assumptions before using either figure.
What can make this comparison wrong?
Customers might switch from one payment method to another without creating a new sale. Order values may change. A different product mix may change product cost. Ad cost per order may rise. A larger basket can require a more expensive shipment.
Returns also matter. Read the provider’s refund terms instead of assuming that every original fee returns with the customer’s money. Our return-cost guide separates a refund from the costs that remain. Keep a matched order cohort so later refunds are not compared with unrelated current orders.
Test contribution, not a checkout slogan
Record the payment method, completed order value, fees actually charged, returns and fulfillment costs. Compare similar periods or a properly designed experiment. A change in conversion rate may reflect a promotion, a traffic-source change or stock availability. Avoid assigning every change to the payment button.
Check payout timing as well as contribution. An amount approved at checkout is not necessarily available in your bank that minute. Cash flow and profit answer different questions.
The decision is yours: does the extra contribution from genuinely additional orders cover the additional cost and work? A provider’s average uplift claim cannot settle that for your store. Ask for the fee schedule, enter your figures and keep the result tied to those assumptions.