Installments and buy now, pay later in Payments & Stripe

Why flexible payment options matter for your checkout

Users abandoning carts at the payment step is a problem every e-commerce team knows too well. One of the most effective levers we've found to reduce that friction is offering installments and buy now, pay later (BNPL) options. When customers see they can split a $500 purchase into four interest-free payments, conversion often jumps noticeably. In this post, we'll walk through how to integrate Klarna, Afterpay, and Affirm via Stripe—three of the largest BNPL providers—so your customers have the flexibility they want and your business captures sales you'd otherwise lose.

Understanding Klarna, Afterpay, and Affirm via Stripe

Stripe bundles several BNPL partners into its Payment Methods ecosystem, making integration simpler than wiring each provider separately. Each has a slightly different checkout experience and eligibility model, but they all share a common principle: the provider finances the purchase and takes on credit risk.

Klarna is the largest BNPL provider globally and offers everything from pay-in-4 to longer financing terms. Klarna handles its own underwriting, so approval depends on factors like payment history and geographic location. The customer journey typically involves a brief form and instant approval or decline.

Afterpay (now part of Square) focuses on a simple pay-in-4 model with payments due every two weeks. It appeals to younger demographics and fashion-forward merchants. Afterpay charges merchants a percentage fee per transaction—typically 4–8%—but the customer sees no interest.

Affirm sits between BNPL and traditional installment loans. It offers customers multiple repayment plans, from 3 months to 48 months, and markets itself as transparent around interest rates. Affirm also performs its own credit assessment.

From an integration standpoint, Stripe lets you accept all three through a single Payment Element or by explicitly offering each as a separate payment method. This gives you flexibility in how you present them to customers.

Higher conversion for large carts

The real business case for BNPL emerges when average order value (AOV) climbs. A customer hesitating at $80 rarely needs financing, but a $400 furniture purchase or $600 electronics bundle suddenly becomes approachable in four installments.

We've seen conversion uplift of 10–25% on high-ticket items when BNPL options are visible at checkout. This is especially pronounced during seasonal peaks—holidays, back-to-school, home renovation season—when customers are already stretched and willing to pay in pieces.

To see measurable impact, measure baseline conversion at different price tiers before and after BNPL launch. Our recommendation: enable Klarna and Afterpay for carts above $200 at minimum; Affirm works well for carts $300+. A/B testing the visibility of each method (e.g., highlighting "Pay in 4" prominently) also drives engagement.

Here's a simplified checkout flow that conditionally shows BNPL:

async function determineAvailablePaymentMethods(
  cartTotal: number,
  customerCountry: string
): Promise {
  const methods = ['card'];

  if (cartTotal >= 200) {
    if (['US', 'GB', 'DE', 'NL', 'SE'].includes(customerCountry)) {
      methods.push('klarna');
    }
    if (['US', 'AU', 'NZ'].includes(customerCountry)) {
      methods.push('afterpay_clearpay');
    }
  }

  if (cartTotal >= 300 && customerCountry === 'US') {
    methods.push('affirm');
  }

  return methods;
}

async function createPaymentIntent(
  cartTotal: number,
  customerCountry: string
) {
  const paymentMethods = await determineAvailablePaymentMethods(
    cartTotal,
    customerCountry
  );

  const paymentIntent = await stripe.paymentIntents.create({
    amount: cartTotal * 100,
    currency: 'usd',
    payment_method_types: paymentMethods,
    metadata: {
      order_id: `ORD_${Date.now()}`,
    },
  });

  return paymentIntent;
}

This logic ensures you're not surfacing BNPL options to customers below the threshold where they matter, reducing friction and keeping your checkout clean.

The provider takes credit risk

One of the biggest operational advantages of BNPL is that you are not the lender. Klarna, Afterpay, and Affirm each perform their own underwriting and absorb default risk. This means your business doesn't need to maintain credit scoring infrastructure or handle collections if a customer fails to pay.

From a cashflow perspective, when a customer chooses BNPL at your checkout, Stripe settles the full order amount to your merchant account immediately (minus the BNPL provider's fee). The customer's installment obligations are between them and the provider—not your responsibility.

This is a crucial operational simplification. Traditional merchant financing or direct lending to customers requires fraud detection, identity verification, credit bureaus, and collection workflows. BNPL providers handle all of that.

That said, you should still monitor chargeback and dispute rates on BNPL orders. If customers frequently dispute BNPL charges claiming non-delivery or quality issues, that's a signal your logistics or product quality needs attention. Stripe's dashboard will surface chargebacks separately by payment method.

Here's how settlement typically flows:

Check fees and availability by country

BNPL economics are driven by provider fees, and those fees vary significantly by method and region. Before launch, confirm both the merchant fee structure and which geographies each provider actually serves.

Klarna fees typically range from 2% to 8% depending on region and risk profile. In some markets (UK, EU), fees are more competitive; in others (US), they tend higher. Klarna is available in ~50 countries, but not all payment plans are offered everywhere.

Afterpay fees sit around 4–8% of order value, again varying by country. Afterpay operates in US, UK, Australia, New Zealand, and parts of Europe. They're particularly strong in ANZ markets and among Gen Z customers.

Affirm fees range from 2% to 10% depending on plan length and merchant category. Affirm is primarily US-focused, though they've begun expansion to Canada and pilot programs elsewhere.

To check current fees and regional availability, log into your Stripe Dashboard and navigate to Settings > Payment Methods. Each provider lists the countries where they operate and typical commission ranges. That said, your account manager or sales contact can often negotiate better rates with volume.

Here's a quick reference checklist before go-live:

• Confirm which BNPL methods Stripe supports in your merchant country.
• Verify each provider's availability in your target customer geographies.
• Request your actual fee schedule from Stripe (it may differ from published rates).
• Calculate AOV impact: If your average cart is $150 and you add Klarna at 5% fee, that's $7.50 per BNPL transaction. Run P&L: if BNPL lifts conversion 15% on a cohort, does that 15% uplift offset the fee cost?
• Check whether each provider has minimum/maximum purchase amounts or customer age restrictions.
• Confirm refund workflows: Does a refund void unpaid installments, or does the customer still owe?

For a real-world example: you're launching a homewares store targeting US and UK customers. Klarna serves both markets. Afterpay serves both. Affirm serves only the US. Your US cart average is $320; UK is $280. You'd enable all three in the US and Klarna + Afterpay in the UK, then monitor fee burn against incremental revenue.

Common mistakes

Assuming BNPL is free to enable. It's not. Each transaction incurs a 2–10% fee. If you enable BNPL without understanding your unit economics, you can end up paying more in fees than you gain in incremental AOV or conversion. Model this in a spreadsheet before launch.

Showing BNPL to every customer regardless of cart value. A customer with a $20 cart doesn't need financing. Cluttering your checkout with four payment methods when only one or two make sense creates decision fatigue and actually lowers conversion. Use the conditional logic above to surface options only when they're relevant.

Not testing refunds and disputes. BNPL refund flows can be complex. If you refund a $200 Afterpay purchase mid-payment schedule, what happens to the customer's remaining installments? Test this end-to-end before launch to avoid customer service chaos. Stripe's test environment supports BNPL; use it.

Neglecting regional restrictions. Some BNPL methods require the customer's billing address to match their provider's service area. Affirm won't approve a Canadian customer even if you integrate the code. Always check Stripe's payment method availability per country before showing options to a user.

Over-optimizing for BNPL instead of core payment stability. BNPL is a conversion lever, but only if your primary card flow is solid. Don't spend two weeks tuning Klarna logic if 3DS authentication on Visa is still broken. Ship fundamentals first.

Key takeaways

• BNPL providers (Klarna, Afterpay, Affirm) handle credit risk and settlement; you get paid immediately by Stripe, and the provider manages installments and default.
• BNPL conversions lift most on high-ticket carts ($200+), especially seasonally. Use conditional logic to surface these methods only above AOV thresholds.
• Fees range from 2–10% per transaction and vary by provider, region, and plan length. Model the math before launch to confirm BNPL lifts revenue above fee cost.
• Regional availability matters. Affirm is US-only; Klarna and Afterpay serve multiple countries. Always check country availability before integrating.
• Test refunds and edge cases in Stripe's test environment. BNPL flows differ from card payments, especially around partial refunds and dispute handling.