Shipping label cost higher than checkout rate (Shopify Shipping / Canada Post) – started in February

Payments + Shipping & Fulfilment
1

Hello,

I am posting here because I have been dealing with a persistent shipping issue with Shopify Support for over a month, and despite multiple conversations with support agents and a ticket escalation, I still have no clear explanation or solution.

I have been using Shopify Shipping with Canada Post for over a year without any issues, but since early February, the shipping label cost is frequently higher than what the customer paid at checkout, even when the package used is smaller and lighter than the default box used for the checkout rate calculation.

This makes absolutely no sense and is causing us to lose money on many orders.

My configuration

Default package used to calculate checkout rates:

14 × 10 × 8 in
0.64 lb

Actual package used when purchasing the label (most common box):

10 × 8 × 4 in
0.3 lb

So the checkout rate is calculated with a larger and heavier box, but when I buy the label with a smaller and lighter box, the cost is often higher.

Example (recent order)

Customer paid at checkout:

$10.93
Package: 14 × 10 × 8
Weight: 2.55 kg

Actual label purchase:

$11.90
Package: 10 × 8 × 4
Weight: 2.39 kg

So:

Smaller box
Lower weight
Higher label price

Important details

This behavior did not happen for more than a year using the exact same setup.

The problem started suddenly in February.

Shopify support has provided several explanations that do not apply to the situation, including:

• weight changes
• dimensional weight rules
• taxes
• carrier pricing rules

However none of these explanations match the actual data.
I even confirmed that taxes are added afterwards when Shopify invoices the labels, so this does not explain the difference either.

Eventually support escalated the issue to developers, but the final response I received was that everything is working as expected, which contradicts the real numbers.

Why this is a problem

Because Shopify calculates the checkout rate automatically, we rely on those numbers to cover shipping costs.

If the label ends up costing more than what the customer paid, we lose margin on every affected order.

My questions to the community

  1. Has anyone experienced shipping labels costing more than the checkout rate recently?

  2. Did something change in Shopify Shipping or Canada Post integration around February?

  3. Is there any way to ensure that checkout rates match the actual label cost when using Shopify Shipping?

At this point I’m mainly trying to understand what changed, since this setup worked perfectly for more than a year.

Any insight would be greatly appreciated.

Thank you.

2

At checkout, Shopify gives an estimated rate based on your default package, product weight, destination, and the carrier rate available at that moment. But when you buy the label, Canada Post rates it again live, and that can include updated surcharges, zone adjustments, minimum billable thresholds, or service-level pricing changes. That’s why a smaller and lighter box can still sometimes cost more.

Since your setup worked for a long time and only changed around February, it does sound like something may have shifted either in carrier pricing or in how rates are being returned now.

When support says it is “working as expected,” they usually mean the carrier returned a valid live rate at label purchase. That does not always mean checkout and label pricing will stay perfectly aligned, so technically the system can be working while still creating a cost gap for merchants.

In your example, the label looks like it should be cheaper, but if that destination falls into a different pricing threshold, the final billed rate can still come back higher.

A practical way to check is to test a few orders using the exact same destination, service, weight, and box size at checkout and again when buying the label. If there is still a difference, then it points more to a checkout estimation mismatch than to your packaging setup.

3

Have you completed an order and immediately printed the label and saw a difference? How about after 1 hour? 5 hours? 1 day? Is the same order different for different areas? Why not test multiple options to see where the flaw is? What about different package size/weight? You can do your own rates, you can literally get the rates directly from Canada Post, you could do flat rates. You can do anything you want. You’re not stuck. You can change anything and everything.

No reason to do nothing if you think there is a major problem. And you can test and test and test.

5

Let me know if you find out anything. I just had the unpleasant experience of the customer’s calculated shipping being $39.67 and my quote for the exact same Canada Post shipping service for the exact same weight and dimensions come in at $54.44. That’s a 37% discrepancy that can’t be explained away with rate fluctuations in the short time period between the order and the shipping. I got the same vague explanations that didn’t make sense.

6

I’m dealing with the exact same issue and have been fighting with Shopify support for over two months now.

Here’s my situation: I deliberately configured a larger default box (14×10×8 inches) in my Shopify settings to ensure the checkout rate is always higher than my actual label cost — a standard practice to protect shipping margins. This worked perfectly until February 2026. Since then, the system has been doing the opposite: I’m consistently paying more for labels than what my customers paid at checkout.

I’ve spoken with over 10 different agents across two tickets (#64143718 and #64874858). The responses ranged from “you’re not losing money” (contradicted by my own invoice) to “a $1-2 difference is expected” to the suggestion that I should add handling fees to make my customers pay more — essentially asking me to pass on the cost of their platform issue to my customers.

I strongly suspect there’s been a bug in Shopify’s Canada Post integration since February 2026, and despite two months of back-and-forth with over 10 different support agents, no one has been able to provide a concrete explanation or fix.

8

I’ve been noticing these issues too, and this week they seem much worse than usual. When buying my Canada Post labels, Shopify is no longer showing the discount amount. Comparing it to my personal Canada Post shipping account, the price was about the same, even though my own account has always been roughly 25% more expensive than Shopify’s rates.

9

I just got another order where the customer paid $18.64, I went to buy a shipping label within an hour of recieving the order, and I am getting charged $24.28 … exact same box dimensions, weight, shipping service, origin and destination…there is literally no reason why the rate could be $5.64 higher in a 10 minute time frame between receiving the order and generating a shipping label.

10

I dont buy my labels via Shopify but does it give you guys a break down?

Basic Cost
Fuel Surcharge
Tax

etc?

If Shopify shows that then you can kinda figure out whats happening. When I buy labels threw Canada Post, it tells me the break down.

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