Does USPS Charge by Weight or Size? Dimensional Weight and Listing Fragile Items on Ebay

Usually, USPS charges by weight, but if you have a light, large package, they charge by size. This is called Dimensional Weight, and it’s important to understand if you’re selling large, light items on Ebay or other sites.

Dimensional weight, which is calculated based on the size of the box, is used instead of the actual weight on some lighter, large packages. If you’re selling big, fragile objects, you need to specify the dimensions of the package when you list the item.

I didn’t do this, and undercharged for shipping on a Pyrex bowl by around ten dollars. It could have been much worse. It could have cost $50!

So, for large, light items, like Pyrex bowls, it’s necessary to pre-pack the item before listing it. Here’s why, in detail.

They say that wise people learn from the mistakes of others. So here’s your opportunity to be wise.

The TL;DR:

  • Pre-pack and weigh all the larger, fragile items.
  • Add the cost of insurance to Priority Select Ground shipping.

What is Dimensional Weight?

USPS has a good website explaining Dimensional Weight, also called DIM weight.

The formula is Length x Width x Height / 194.

So for a 16 x 15 x 11 package:

( 16 x 15 x 11 ) / 194 = 14 lbs

However, it’s not that simple. There’s some fine print on the page that says, in different situations, different prices apply. Packages with a Girth + Length > 84 may pay a 20 pound rate, for example.

So, you can go to that page and try out different dimensions and weights, and see the postage.

Here are some dimensional weight postages for a package that weighs 6 pounds, going to a nearby state. The first one, I’m pretty sure, is a package that was smaller than the DIM Weight threshold.

12 x 12 x 10 = $13.77

16 x 15 x 11 = $24.94

13 x 13 x 13 = $22.37

17 x 13 x 10 = $22.37

19 x 15 x 10 = $26.22

36 x 15 x 8 = $33.31

That’s a difference of up to $20 for the same weight!

Here are some dimensional weights for a 4 pound package from California to Maine using Retail Ground:

19 x 14 x 10 = $19.60

16 x 14 x 10 = $19.60

14 x 14 x 10 = $19.60

Here are the prices for the same 4 pound package from California to Maine, using Priority Mail:

19 x 14 x 10 = $49.45

16 x 14 x 10 = $45.45

14 x 14 x 10 = $42.35

The Weight of Boxes and Packaging can be Significant

If you’re shipping a backpack, you don’t worry about the packaging weight: you should just use huge shipping bags.

If you’re shipping a glass bowl, then you worry a lot about packaging. You need to use box-within-a-box and pack the box with padding.

Boxes weigh between half a pound and two pounds, generally. Two boxes add considerable weight to the package.

So, go back to that USPS DIM weight calculator and add a couple pounds to your package.

Fragile Items Require More Packaging and Have a Larger Volume

Packing materials can weigh a lot. If you use crumpled paper, it’s going to weigh a lot: it’s made from trees! You’re packing the box with a puffed-up log.

That’s why all the companies use those air pillows. Air, while not weightless, is light. Plastic isn’t light, either, but there’s very little plastic.

The box-within-a-box packing method adds around 6 inches to each dimension of an object. So, if you have a 8 x 8 x 5 bowl, your mailing box will be 15 x 15 x 11.

You can cheat and go a little smaller, but not by much. You need two inches of clearance on each side of the object, or USPS insurance may refuse to cover it if they break it.

So, go back to that USPS DIM weight calculator, and add 6 inches to each dimension. You should see some big changes.

What does this mean for you?

You Must Pre-Pack Items

I haven’t done this, but I need to do this: I must completely pre-pack the large, fragile items.

In the meantime, I’ve inflated the dimensions and weight of several items I have for sale.  Once I have them packed, I can update the listings with accurate weights and dimensions.

I noted that pre-packing and accurate weight is important for international sales before, but it also applies domestically, because…

The Distance a Package Travels Matters

The more something weighs, the more it costs to ship. How much more can be huge.

A bowl sent from Los Angeles to Los Angeles may cost around $10.

Sending the same bowl to Bangor, Maine, could cost over $60.

My error cost me $10. It could have cost me $50 if it were to a distant state.

The customer sees a calculated shipping cost in the listing.

So, if you don’t add the dimensions to the listing, the customer may see a very low shipping cost, when it’s going to cost a lot more.

Ground or Priority Mail?

Ground is cheaper, but Priority Mail is safer. The package stays in the system a shorter time, so it’s less likely to be dropped. So, I always prefer Priority Mail.

However, the cost of Ground is a lot less, so I’m going to offer it. I just need to add the cost of insurance to the handling costs.

I’m trying to work out a formula for this, but I think it’s something like:

B = probability that a package will break (assume .20)
P = average postage cost (assume 30)
I = package insurance cost

C = I + B * P

Postage cost is not covered by insurance, so it won’t be recovered. You spread that loss over all your packages.

If the insurance is $2.10, and the postage is $20, then the extra handing fee to charge is 2.10 + .2 * 20 = $6.10.

(I know .20, or 1/5, of packages sounds like a lot of breakage, but I’ve been watching some reseller videos on YouTube, and some of the people say 1/3 of their items break.  I’m pretty shocked, because, so far, I haven’t had a broken item.)

Special Handling – Fragile?

“Special Handling – Fragile” is a special service for fragile items, sold at the counter for $10.35, that will cause your package to be processed by hand rather than through the normal automatic sorting.

Is it worth that? I think it depends on the item. At a $10 difference, if the item is small, using Priority Mail may make sense.

The Drop Test

Instead of worrying about whether something may break, I do some drop tests after I package the items.  I drop the box from two or three feet off the ground. If I hear anything moving around, I open up and re-pack the item.

If it breaks, then, better that it broke during the test, than during delivery.

As long as I package it and test it before selling it, the damage is limited to the time I spent packaging it (poorly) and the cost of the item.

What this Means for Sourcing

I’m already used to adding the cost of postage to heavy clothing items like pants: “will someone pay $8 for shipping this thing?”

I’m also used to adding the cost of postage for things like mugs and shoes: “will they pay $10 – $15 in shipping for this?”

Well, it’s even tougher with large, fragile items: “will they pay $15 to $60 in postage?”

On the $15 side, the answer is “yes”, if it’s an unusual item or an expensive item.  On the $60 it’s probably “no”, unless it’s an expensive object.  Is there a sufficiently large market on the West Coast and western states? Sometimes, yes.

Author: John

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