What Is Shop Pay Installments Cost?
Shop Pay Installments cost is the processing fee a merchant pays when a customer chooses to split an eligible purchase into payments. The merchant receives the purchase amount upfront, less the fee; Affirm manages the customer’s installment repayments.
The fee is higher than standard Shopify Payments processing, so the decision is whether the added cost is offset by incremental contribution from orders that would otherwise be smaller or not happen. A conversion lift or higher average order value (AOV) is not automatically profit: subtract product, fulfillment, marketing, and payment costs before judging the return.
Shop Pay Installments Cost Formulas
Installment fee per order = (Order amount × Merchant fee rate) + Merchant fixed fee
Standard fee per order = (Order amount × Standard processing rate) + Standard fixed fee
Extra cost per installment order = Installment fee − Standard fee
Monthly installment fees = Installment order count × Installment fee per order
Blended effective rate = Total payment fees ÷ Total processed revenue × 100
To assess the sales lift, compare the additional contribution—not just additional revenue—with the extra processing cost:
Incremental contribution = Incremental revenue × Contribution margin
Net estimated benefit = Incremental contribution − Extra installment processing cost
ROI = (Net estimated benefit ÷ Extra installment processing cost) × 100
The calculator’s conversion-lift and AOV-lift inputs are estimates, not guaranteed results. Use your store’s analytics and contribution margin to decide whether the projected lift covers the fee premium.
How to Use This Calculator
- Enter
monthlyRevenue— total monthly sales, used to estimate the share processed through installments. - Enter
installmentPct— the percentage of orders expected to use installments. A reasonable starting assumption for eligible orders is often within the calculator’s 10–30% guidance. - Enter
avgOrderValue— the average value of installment orders. Shop Pay Installments is generally available for eligible orders between $50 and $17,500. - Set
merchantFeeandmerchantFixed— enter the installment percentage fee and fixed per-order charge. The provided default percentage is 5.9%; confirm your current rate in Shopify. - Set
standardRateandstandardFixed— enter your Shopify Payments card rate and fixed charge to make a like-for-like comparison. - Estimate
conversionLiftandaovLift— use conservative estimates from a test or past campaign data. These assumptions drive the estimated sales impact, not a promise of results. - Review the extra cost, blended effective rate, and estimated ROI — check whether added contribution is greater than the added fees before expanding promotion.
Step-by-Step Example
Suppose a Shopify store processes $30,000 in monthly revenue, with 20% of its sales using installments and an average installment order of $120. For this comparison, use a 5.9% + $0.30 installment fee and a 2.9% + $0.30 standard rate.
| Calculation | Arithmetic | Result |
|---|---|---|
| Installment sales volume | $30,000 × 20% | $6,000 |
| Estimated installment orders | $6,000 ÷ $120 | 50 |
| Installment fee per order | ($120 × 0.059) + $0.30 | $7.38 |
| Standard fee per order | ($120 × 0.029) + $0.30 | $3.78 |
| Extra cost per installment order | $7.38 − $3.78 | $3.60 |
| Monthly installment fees | 50 × $7.38 | $369 |
| Standard fees on the same sales | 50 × $3.78 | $189 |
| Extra monthly processing cost | $369 − $189 | $180 |
The installment transactions have an effective fee rate of 6.15% because the fixed charge is included. To justify the added monthly cost, the store needs more than that amount in incremental contribution after product and fulfillment expenses—not merely in extra sales revenue.
Interpreting the ROI: Revenue Is Not Profit
A conversion lift estimates how many more visitors complete an order; an AOV lift estimates how much more those orders are worth. The two effects can overlap, so avoid adding their percentages together unless your measurement method supports that calculation. Compare a test group with a similar group that does not see installments, and track conversion, AOV, refunds, and contribution margin.
Shop Pay Installments is available for eligible order amounts from $50 to $17,500, but eligibility does not guarantee customer approval or use. The CFPB’s research on buy now, pay later describes BNPL as a form of consumer credit, so merchants should treat its presentation as a financing option and avoid implying that every shopper will qualify.
Your store still needs to handle normal order operations, including returns, customer service, and disputes about goods or delivery. For financial planning, track when payouts arrive alongside supplier and fulfillment bills; the SBA’s guide to managing business finances explains why cash-flow monitoring matters even when sales are growing. For other provider comparisons, use the Klarna, Afterpay & BNPL Fee Calculator.
Shop Pay Installments Benchmarks
Use these ranges as starting assumptions for testing, not as guaranteed results. Adoption depends on eligibility, product price, customer mix, how the option is presented, and the checkout experience.
| Store or order profile | Planning benchmark | What to test |
|---|---|---|
| Eligible orders across a store | 10–30% installment adoption | Compare adoption by product and traffic source |
| Orders around $100–$500 | Often a strong fit for installment messaging | Test whether conversion or basket value improves |
| Fashion, electronics, home goods, and fitness equipment | Often higher customer interest | Measure incremental contribution by category |
| Orders outside $50–$17,500 | Not eligible for installments | Keep standard payment methods clear |
The FTC’s advertising and marketing guidance is a useful reference when writing promotional claims: describe the offer accurately and do not present estimated savings or approval as guaranteed.
6 Tips to Test Installment Economics
- Change adoption from 12% to 18% in the calculator to see how much higher usage changes total fees; use a test result rather than assuming every eligible buyer will choose installments.
- Change your conversion-lift assumption from 8% to 15% and check whether the estimated incremental contribution clears the fee premium.
- Change AOV lift from 10% to 25% for a product category where customers frequently add accessories, then compare the result with actual basket data.
- Separate eligible from ineligible sales in your Shopify reports so orders outside the installment limits do not inflate your adoption estimate.
- Test placement in product details and checkout against a control group; prominent messaging may increase use, but only a controlled comparison shows whether it adds profitable orders.
- Include refunds and disputes in your review. Use the Chargeback Cost Calculator to estimate dispute exposure alongside payment fees.
- Compare alternatives before committing to a promotion. The Stripe Fee Calculator can help you assess another processor’s costs, while this calculator focuses on installment adoption and lift assumptions.
Frequently Asked Questions
How much does Shop Pay Installments cost merchants?
Shop Pay Installments charges merchants 5.9% + $0.30 per installment transaction under the fee assumption used here, roughly double a standard Shopify Payments rate in many cases. Customers pay 0% interest on four-payment plans, and the merchant fee funds that customer offer; enter your current Shopify rate to calculate the exact premium for your store.
Is Shop Pay Installments worth the higher fee?
It is worth testing when the additional contribution from higher conversion or larger orders exceeds the fee premium. BNPL adoption and sales effects vary by store, so compare a controlled test with your baseline and include product, fulfillment, refund, and marketing costs rather than treating estimated revenue lift as profit.
What are the order limits for Shop Pay Installments?
Shop Pay Installments is available for eligible orders between $50 and $17,500; orders outside that range show other payment options instead. The $100–$500 AOV range can be a useful starting point for testing, but customer eligibility and product category also affect adoption.
Do merchants get paid upfront with Shop Pay Installments?
Yes, merchants receive the purchase amount upfront, less the processing fee, while Affirm collects the customer’s payments over time. Affirm assumes the repayment risk for the installment plan, but merchants still need to manage ordinary returns, service issues, and disputes about the underlying order.
What percentage of orders use Shop Pay Installments?
A common planning range is 10–30% of eligible orders, with adoption varying by average order value, product category, and how clearly the option is presented. Measure your own eligible-order adoption in Shopify rather than applying a broad benchmark to every sale.
About This Calculator
Luis Dev Studio built this calculator for Shopify merchants comparing installment costs with standard payment processing and estimating possible ROI. For help interpreting your results or improving your store’s payment setup, contact us or review our Shopify services.
Updated by Luis Gonzalez · Jun 2, 2026