Magento 2 Checkout: Stripe Payment Total Incorrect for Multiple Items

Below are a few areas to investigate and some suggestions for troubleshooting the issue:

1. Verify How Stripe Receives the Order Total

Since the amount shown on the final order placement page is coming from Magento but then sent via the Stripe integration, first double-check that the value passed to Stripe (typically via a PaymentIntent) is exactly what Magento calculated. In many Magento Stripe integrations the PaymentIntent is created before the order is placed, so any miscalculation there could affect the final amount.

• Confirm that the Magento module isn’t inadvertently multiplying the amount when creating the PaymentIntent.
• Check if the PaymentIntent amount (and its currency configuration) is set directly from the Magento quote total.

2. Review the Magento Stripe Module Version and Known Issues

There have been cases where new versions of the Stripe module for Magento introduced unexpected behavior (for example, in how incomplete PaymentIntents were handled). Review the extension’s release notes or support FAQs to see if others have experienced inflated amounts or similar miscalculations.

• Ensure you’re running a version of the module that is known to work well with Magento 2 and PHP 8.2.
• Look for any patches or configuration notes that mention multiple quantities or adjustments in totals when using Stripe.

3. Check Theme Customizations and Checkout Block Configurations

Since you’re using the SM Market Theme, there might be template or JavaScript customizations that affect how totals are calculated at checkout.

• Compare the checkout totals when using a default Magento theme versus your custom theme.
• Inspect the XML configuration related to the checkout and confirm that there is no duplicate block or JavaScript issue that could be summing the amount more than once.

4. Examine the Payment Flow in the Stripe Integration

With modern integrations using the PaymentElement or PaymentIntent, Magento sometimes creates an initial PaymentIntent with an "incomplete" status. That early PaymentIntent should exactly capture the order total. Look into the following:

• If the module re-creates or adjusts the PaymentIntent after order review, verify that it isn’t re‑calculating the amount by multiplying the quote’s line items.
• Review any custom code or overrides that hook into Stripe’s PaymentIntent creation process.

5. Review Server and Debug Logs

Both Magento and Stripe’s side of the integration may provide logs that help pin down the discrepancy.

• Check Magento logs (for example in var/log/stripe_payments_webhooks.log or Magento’s system/exception logs) for any errors or warnings during the checkout process.
• Log the PaymentIntent payload being sent to Stripe to ensure the amount value is correct.

Summary

The inflated total could be caused by:

• An incorrect amount calculation in the Magento Stripe module (possibly creating or updating the PaymentIntent incorrectly).
• A custom checkout override (via theme or module) that inadvertently multiplies cart totals.
• A mismatch between Magento’s quote total and the amount transmitted to Stripe.

By confirming the exact value passed to Stripe, reviewing the recent module version and theme customizations, and checking both Magento and Stripe logs, you can pinpoint whether the error lies in the calculation process or in the integration itself.

If after these steps the issue remains unclear, consider reaching out to the Magento Stripe module support with detailed logs and a description of the miscalculation.