To limit free shipping by weight, add the condition Cart weight Is at most 20 kg next to your cart value condition, and set the rates to Free. Shopify’s own free shipping discount has no weight condition. Its only minimums are a purchase amount or a number of items. RM: Advanced Free Shipping checks the cart weight in g, kg, oz or lb, alone or together with cart value, products and location. It costs $9.90 USD every 30 days, with a 7-day free trial, billed by Shopify.

What the customer gets

In this example the offer is free shipping over $100, up to 20 kg. The rates are Standard $8.90 and Express $24.90.

  • A $120 cart weighing 6 kg: both conditions pass. Standard and Express are free. The customer pays $120.
  • A $120 cart weighing 28 kg: it’s over 20 kg, so it doesn’t qualify. With Standard, the customer pays $120 + $8.90 = $128.90.
  • An $80 cart weighing 3 kg: it’s under $100, so it doesn’t qualify. With Standard, the customer pays $80 + $8.90 = $88.90.

The weight is each product’s weight in Shopify, times the quantity. Two 4 kg planters and one 2 kg bag of soil weigh 10 kg.

Set it up

  1. In the app, click Create Shipping Discount. Under Discount method, choose Automatic discount, and enter a Title such as “Free shipping over $100”.
  2. In Conditions, click Add condition. Keep Cart total, set Is at least and enter 100.
  3. Click Add condition again and choose Cart weight. Set the operator to Is at most.
  4. Choose kg first, then enter 20. The unit starts on g (grams), and 20 g is not 20 kg.
  5. In Discount setup, set Delivery type to Shipping, Which rates to All shipping rates and Discount value to Free.
  6. Click Create discount.

Both conditions sit in the same rule group, so both must pass.

The Create shipping discount page with Automatic discount selected, a Cart total Is at least $100 condition, and Discount setup set to Shipping, All shipping rates, Free

The screenshot shows the $100 condition. Add the Cart weight condition under it with Add condition.

Variations

  • Free shipping on light parcels only: use just Cart weight Is at most 2 kg, with no cart value condition.
  • A shipping credit for heavy orders: in a second discount, use Cart weight Is greater than 20 kg and Cart total Is at least 100, with Fixed Amount Off 15. With live carrier rates, a $42.00 heavy Standard rate drops to $27.00.
  • Free Standard under 20 kg, Express at full price: set Which rates to Choose specific rates and select Standard.
  • Free shipping under 5 lb in the US: choose lb, enter 5, and add Shipping country Is one of United States.
  • Light parcels, or any cart over $150: open the ⋯ menu on Conditions and choose Add rule group. Put the weight in one group and Cart total Is at least 150 in the other.

Good to know

  • To count every product, give every product a weight. Products with no weight set count as 0, so a cart full of unweighed items passes “Is at most 20 kg”.
  • To mix units, do nothing. Products weighed in g, kg, oz or lb are converted to the unit you picked.
  • To leave oversized items out by product, not weight, use Product collection Does not contain with a collection such as “Oversized”. See free shipping except oversized items.
  • To test it, turn on Test mode, check out with the shipping first name ABC123, and try a cart just under and just over 20 kg.

Install RM: Advanced Free Shipping from the Shopify App Store.