Confused on a shipping option

[NovelNerd]

When I try to calculate a price for a box with priority shipping if it goes over the 12 inches mark on dimensions that jumps the price up rather high because it falls into the "large boxes" category. When I take that same box to the post office though they calculate it with priority and get the cheaper option based on the weight ect.  A good example I had a box that had a dimension that was lets say 14 inches, and sending priority according to my putting it into the usps website had the box at around $30 to ship. I took it to the post office, and they did it for around $15ish.

Why exactly does that happen? We both got the same calculations on the weight, but they did not measure my box even though it's obviously larger.  When people have gotten the boxes there has been no mention of extra fees or postage errors. I'm a bit confused on this.

[NoDivision]

Hm, I'm not sure. When I put in a box with the dimensions of 14x10x10, the prices were pretty much the same as with a box under 12", for both standard and priority. When I tried one at 20x10x10, the priority price jumped but the standard mail remained the same. So it really varies but just how large "large" is. If you have a truly very large package it may be that the people at the post office they are doing you a favor and not charging you for the size.

[ponylady]

I am not sure either 

I very rarely use USPS to print my labels. I know through Ebay it states "Up to 13 ounces and 84 inches in combined length and girth." for First Class and "Up to 70 pounds and 108 inches in combined length and girth. Girth is the distance around the thickest part of the package." for Priority LARGE Package. So I actually never have to plug in a dimension or have I been asked to? I guess because I have never shipped anything larger than that. 

The only explanation I have is that it could be maybe your not entering something correct?? I know on the rare occasion when I have used USPS's site, I was confused and ended up just taking it to the PO myself.

[NoDivision]

The cutoff for priority before it goes to "large package" size seems to be 48" around the widest point.

For example - I put in a package weighing 3 pounds going from louisville to beverly hills.

Entering it under regular package with no dimensions:
Priority: $15.25
Standard: $12.77

Entering it under large package using 12x12x12 (48"):
Priority: $15.25
Standard: $12.77

Entering it under large package using 14x10x10 (48"):
Priority: $15.25
Standard: $12.77

Entering it under large package using 16x8x8 (48"):
Priority: $15.25
Standard: $12.77

Entering it under large package using 13x12x12 (50"):
Priority: $36.50
Standard: $12.77

So, you can have dimensions over 12" and it still falls under regular pricing. The Standard Mail price doesn't change over 48", but the priority mail does. I think the limits that Ponylady lists from ebay are the overall limits of that postal method - as in if your package is over 84" total you can't use priority shipping and if it's over 108 inches you have to ship it a different way completely. But up to that point there are different price levels depending on size, and the cutoff for the first price level for priority seems to be 48" at the widest point.

So chances are if you enter it online to check a price and it's over those dimensions it will show you the more expensive price for priority, but I'm guessing that when you take it to the post office it depends on the postal worker. They might look at the box and think it's small enough and not measure it and just use the regular pricing.