Weight-based shipping rates not working: the four causes

RateGuard · Last checked 14 August 2026

A weight-based rate applies only when the cart's total weight falls inside a bracket you defined, so a product with no weight or a gap between brackets returns no rate rather than a wrong one. Both halves have to be right, and both fail silently. A weightless product counts as zero, which either drops the cart into your cheapest rate and undercharges you, or falls below your lowest bracket and shows the shopper nothing at all. A bracket that stops at 2 kg leaves every heavier cart with no option, which is why this usually surfaces the first time somebody orders three of something rather than at setup.

The two halves of a weight-based rate, and both have to be right

A weight-based rate is a bracket, from a minimum to a maximum, with a price. For it to apply, the cart's total weight has to fall inside that bracket, which means every product needs a weight and the brackets need to cover every weight a cart can reach. Missing either half returns no rate rather than a wrong one.

Settings → Shipping and delivery → the profile → the zone → the rate → “Based on order weight”

1. Products with no weight count as zero

A shippable product with an empty weight field is not skipped, it is counted as 0 kg. Two consequences, and they look nothing like each other.

• If your lowest bracket starts at 0, the cart drops into your cheapest rate. Checkout works and you undercharge, which is worse than an error because nothing tells you.
• If your lowest bracket starts above 0, say 0.1 kg, the cart matches nothing and checkout shows no shipping option at all.

Products → open a product → Shipping → Weight

Export the catalogue and sort on the weight column rather than checking by hand. Look for empty cells and for zeros, which are different problems with the same effect.

2. Brackets that leave a hole

Three shapes of hole, in the order they turn up.

1. No upper bound. Rates defined 0-2 kg and nothing above. Every cart over 2 kg gets nothing. This surfaces the first time somebody orders three of something.
2. A gap between brackets. 0-2 kg and 3-10 kg leaves everything between 2 and 3 kg with no rate. Brackets have to touch.
3. A lowest bracket that does not start at zero, which chains straight into the weightless products above.

Write your brackets out on one line and read them as a number line: 0-2, 2-10, 10-∞ is complete, 0-2, 3-10 is not, and 0-2, 2-10 is missing everything heavy.

3. The unit is a store-wide setting, and mixing it up is silent

Your store has a default weight unit, and a rate defined in kilograms against products entered in pounds is off by a factor of 2.2 in whichever direction hurts. Nothing warns you, because both numbers are valid.

Settings → General → Store defaults → Unit system and Default weight unit

4. Weight-based and price-based rates in the same zone

Both can coexist, and a cart that matches neither gets nothing while a cart that matches both is offered both. If a zone shows two options when you expected one, that is this, not a bug.

Written 14 August 2026. Admin paths reflect the Shopify admin as of that date; Shopify moves settings occasionally, and this page is re-checked when it does.