Quick answer
Free shipping usually fails because the cart does not match the exact shipping profile, zone, rate condition, discount condition, or customer/product eligibility. Multiple shipping profiles are a common source of confusion.
Symptom
The store advertises free shipping, but checkout still charges shipping or does not show the free shipping rate.
Most likely causes
- Products are in different shipping profiles. Shopify can combine rates from multiple profiles, which surprises merchants.
- The cart does not meet the rate condition. Price/weight thresholds may not match the cart as expected.
- The free shipping rate exists only in one zone. The customer’s address may not be covered.
- Discount eligibility does not match. Customer, product, collection, usage, or purchase-type rules may exclude the order.
- Shipping discount vs shipping rate confusion. A free shipping rate and a free shipping discount are different setups.
Quick checks
- Confirm whether free shipping is a shipping rate or a discount.
- Check the cart subtotal, discount rules, and whether taxes/shipping are being included or excluded as expected.
- Open the shipping profile and confirm every product in the cart belongs to a profile with the free shipping rule.
- Test with one product at a time, then mixed carts.
- Test the customer address in the target zone.
Theme, app, or code checks
- If only mixed carts fail, investigate multiple shipping profiles.
- If only one product fails, check which profile it belongs to.
- If only discount-code free shipping fails, check discount eligibility and combinations.
- If subscription products are involved, check whether the discount applies to subscription and/or one-time purchases.
When to stop guessing
Stop tweaking the banner copy and test the actual checkout math. If free shipping works for one product but not mixed carts, the problem is likely profiles/rate combination logic, not the theme.
Prevention checklist
- Use one shipping profile where possible if the rules can be expressed cleanly.
- Test free shipping with every product type before advertising it sitewide.
- Document whether promotions use free shipping rates, automatic discounts, or discount codes.
- Check mixed-cart behavior before launching campaigns.