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Adding Buy Now Pay Later to Your Online Store

Buy now pay later (BNPL) lets customers split purchases into installments, typically four interest-free payments over six to eight weeks. Merchants pay a fee of 4% to 8% per transaction to the BNPL provider, which is higher than standard credit card processing, but stores that add BNPL consistently report 20% to 30% higher average order values and 10% to 20% higher checkout conversion rates. The fee increase is more than offset by the revenue increase for products priced between $50 and $2,000.

Step 1: Decide If BNPL Fits Your Business

BNPL is not equally effective for every product type or customer base. Before investing time in setup, evaluate whether it matches your business:

Best product price range: $50 to $2,000. Below $50, splitting into four payments of $12.50 does not feel meaningful to most customers. Above $2,000, traditional financing options (credit cards, personal loans) are more commonly used and BNPL approval rates drop significantly because the providers take on more risk.

Best categories: Fashion and apparel, consumer electronics, home goods and furniture, fitness equipment, beauty products, and outdoor gear. These are categories where customers are motivated by the item but deterred by the single-payment price point. BNPL converts "I want it but not at that price right now" into a completed sale.

Best customer demographics: Millennials and Gen Z are the heaviest BNPL users. Approximately 45% of Gen Z consumers and 37% of millennials have used BNPL at least once. If your customer base skews younger (18-40), BNPL adoption will be higher. For customer bases that skew older or more affluent, BNPL adoption is lower but can still drive incremental sales.

Where BNPL underperforms: Grocery and consumables (too low-value and too frequent), luxury goods over $5,000 (customers use AmEx or store financing), B2B transactions (businesses use terms, not consumer installments), and digital products or services with immediate delivery (higher fraud risk and higher return rates with BNPL).

Step 2: Choose a BNPL Provider

Afterpay (Block/Square)

Afterpay splits purchases into four interest-free payments every two weeks. The customer pays the first installment at checkout and the remaining three automatically over six weeks. Afterpay pays the merchant the full purchase amount upfront (minus fees) within one to two business days.

Merchant fees are 4% to 6% per transaction plus $0.30. The exact rate depends on your category, volume, and negotiation. Afterpay's app has over 20 million active US users who browse and discover merchants through the app, providing a free marketing channel. Afterpay is strongest in fashion, beauty, and lifestyle categories. It integrates with Shopify, WooCommerce, BigCommerce, Magento, and Squarespace.

Klarna

Klarna offers three payment options: Pay in 4 (four interest-free installments), Pay in 30 (full payment deferred 30 days), and Financing (6 to 36 month plans with interest for higher-ticket items). This flexibility lets you offer installments for a $75 dress and financing for a $1,500 sofa under the same provider.

Merchant fees range from 3.29% to 5.99% plus $0.30, depending on the payment product and your volume. Klarna has the strongest presence in Europe, with over 150 million users globally. If your store sells to European customers, Klarna is the BNPL provider they are most likely to recognize and trust. Klarna integrates with Shopify, WooCommerce, BigCommerce, Magento, PrestaShop, and most major platforms.

Affirm

Affirm offers longer-term financing (3, 6, 12, 18, or 36 month plans) with interest rates ranging from 0% to 36% APR depending on the customer's creditworthiness and the merchant's subsidy arrangement. Merchants can choose to subsidize the interest (offering 0% APR to customers and paying a higher merchant fee) or pass the interest cost to the customer (paying a lower merchant fee).

Merchant fees range from 5.99% to 8% for 0% APR programs. Affirm is strongest for higher-ticket purchases ($200 to $10,000+) where the longer payment terms make a meaningful difference. It is widely used in electronics, furniture, home improvement, and fitness equipment. Affirm powers "Pay Monthly" options for Amazon, Walmart, and Peloton. It integrates with Shopify, WooCommerce, BigCommerce, and Magento.

Shop Pay Installments

If you are on Shopify, Shop Pay Installments is the simplest BNPL option. Powered by Affirm, it offers customers the option to split purchases into four biweekly payments (for orders $50 to $999) or monthly payments up to 12 months (for orders $150 to $17,500). The integration is automatic if you have Shopify Payments enabled. Merchant fees are comparable to Affirm's direct fees.

The advantage of Shop Pay Installments is zero setup effort for Shopify merchants. It appears automatically at checkout alongside Shop Pay's one-click payment, and the installment messaging can be added to product pages through Shopify's theme editor. The disadvantage is that it only works on Shopify.

Step 3: Apply and Get Approved

BNPL providers evaluate your business before approving you. They assess your product category (some categories like alcohol, firearms, and gambling are prohibited), your website quality (professional design, clear product descriptions, visible contact information), your return and refund policy, and your estimated monthly sales volume.

The application process for Afterpay, Klarna, and Affirm is online and typically requires your business name and legal entity, your website URL, your product category, your average order value and estimated monthly volume, and your return/refund policy URL. Approval takes one to five business days. Some providers require a minimum monthly sales volume (often $1,000 to $5,000) before they will approve your application.

Step 4: Install and Configure

On Shopify: Install the provider's app from the Shopify App Store (Afterpay, Klarna, or Affirm). The app adds the BNPL option to your checkout automatically. For Shop Pay Installments, enable it in Shopify Settings under Payments. No app installation required.

On WooCommerce: Install the provider's WordPress plugin (Afterpay Gateway, Klarna Payments, or Affirm for WooCommerce). Configure the plugin with your merchant credentials (provided during onboarding). The plugin adds the BNPL option to your WooCommerce checkout page.

On BigCommerce: Most BNPL providers are available as BigCommerce checkout integrations. Enable them through the BigCommerce control panel under Store Setup, then Payments. Configuration involves entering your merchant ID and API keys.

Step 5: Add Installment Messaging to Product Pages

The most effective BNPL implementations display installment pricing on product pages, not just at checkout. A product priced at $200 should show "or 4 interest-free payments of $50 with Afterpay" directly below the price. This reframes the purchase decision from "$200 now" to "$50 now," which is a fundamentally different psychological calculation.

All major BNPL providers offer JavaScript widgets that automatically calculate and display installment amounts based on the product price. These widgets update dynamically if the product has variants with different prices. Place the widget directly below the product price, above the "Add to Cart" button, where it gets maximum visibility.

Add similar messaging on the cart page, showing the installment amount for the total cart value. Some merchants also add BNPL messaging to category pages and promotional banners to raise awareness before customers reach the product page.

Step 6: Monitor Performance

After enabling BNPL, track these metrics to evaluate its impact:

BNPL adoption rate: What percentage of orders use BNPL versus card payments. Typical adoption rates range from 10% to 25% of orders. Higher adoption in fashion and lifestyle, lower in electronics and B2B.

Average order value (AOV) change: Compare AOV for BNPL orders versus card orders. Most merchants see BNPL AOV 20% to 30% higher than card AOV because customers are willing to add more items or choose premium options when they can spread the cost.

Checkout conversion rate: Compare conversion rates before and after adding BNPL. A typical improvement is 10% to 20% in overall checkout conversion, with higher improvements on mobile where BNPL eliminates the friction of entering card details.

Return rate: Some studies show BNPL orders have higher return rates than card orders, particularly in fashion. Monitor whether BNPL is driving genuine demand or enabling impulse purchases that get returned. If BNPL return rates are significantly higher, the net revenue impact may be lower than the gross numbers suggest.

Net revenue impact: Calculate the additional revenue from higher AOV and conversion, subtract the incremental processing cost (BNPL fees minus what you would have paid on card processing), and subtract the cost of any additional returns. The net impact is almost always positive for stores in the sweet spot of $50 to $2,000 products with younger demographics.