What is triggering higher shipping cost for small USPS Ground Advantage packages

[blizzard2]

I ship mostly small light packages using USPS Ground Advantage. In the past I knew to be careful when listing larger packages as they might trigger dimensional weight or other high shipping costs if measurements weren't precise.

Lately I've noticed that even a large bubble envelope can trigger higher shipping costs, and I can't figure out why and what the new rules are! 

For example, bubble envelope, USPS Ground Advantage, package size 11 x 13 x 2 ebay shipping label cost $8.57; but package size 11 x 13 x 3 label cost $9.02. Not a big difference so I have't been concerned. But it would be helpful to be aware of what's triggering the added postage! Any ideas? Thanks!

[ebooksdiva]

USPS did increase costs in July. Increases vary by weight and zone. 

https://community.ebay.com/t5/Announcements/July-2024-USPS-Rate-Changes/ba-p/34538677

[dolcetreasures]

Yeah the prices are getting absolutely out-of-hand. 

[robbie31415]

The reason you are seeing price differences is for packages over 1 lb may be assigned to cubic pricing.

Your first example falls under tier 2 and your second one falls under tier 3.

This site has some information to help you understand and it has an easy cubic calculator for you.

https://www.pirateship.com/usps/ground-advantage-cubic

[neocurio]

If only they would offer first class with tracking!

[blizzard2]

Yes, I did see the changes from July. But this is happening when there are no differences in the weight or zone.  The example I gave is for the exact same weight (2 pounds) and zone and date shipped, the only difference is the slight increase of 1 inch in package thickness. I don't think it's an eBay error, I think it's some actual change to USPS Commercial rates, but I can't figure out what the new rules are. Anything I've found related to package size doesn't apply to small packages like this. 

[tobaccocardyahoo]

Ebay now offers cubic pricing for GA and Priority

You may be getting cubic pricing on your shipments with small dimensions at the same weight. This is not the same as dimensional price charges, it is a much smaller amount.

[nobody*s_perfect]

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@blizzard2 wrote:

Yes, I did see the changes from July. But this is happening when there are no differences in the weight or zone.  ... the only difference is the slight increase of 1 inch in package thickness. ...

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Cubic rates are based on package volume, in increments of .1 cubic foot.  Your package that's 11 x 13 x 2 has a volume of 0.165 cubic foot, so it ships at the rate for .2 cubic foot.  But increase the thickness by just one inch to 11 x 13 x 3, and the volume increases to .248 cubic foot so it ships at the .3 cu ft rate.