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In the summer of 2019, the US Postal Service changed the way it calculates shipping charges. The USPS has added new dimensional weight pricing. As a result, USPS shipping rates for some packages will increase substantially. The USPS shipping change happened during a relatively slow time of the year. During the busy holiday season, shippers may get an unwelcome surprise when they see the price tag for their USPS shipping.

How many gifts were returned to your ecommerce business after the 2018 holiday?

The USPS shipping change involves a different way to calculate the dimensional or DIM weight of packages. Here’s everything you need to know about the change to USPS shipping calculations and how to avoid DIM weight charges.

What Is DIM Weight Pricing?

Dimensional or DIM weight pricing is a formula that carriers use to determine the cost to ship a package. DIM weight pricing allows carries to incorporate the size of the packages they ship into their pricing structure. After all, the number of packages that can fit on one truck or in one container depends as much on the size of the box as its weight.

If your package is heavy or small, you don’t need to worry about DIM prices. You’ll pay for USPS shipping or shipping with other carriers based solely on the actual package weight. However, if you ship something relatively light in a large box, you may pay more than you expected to.  Read on for examples of how DIM weight pricing can affect your USPS shipping costs.

Changes to USPS Shipping Rates

The changes that the US Postal Service instituted in June 2019 affect only packages over 1 cubic foot in area. The new DIM pricing for USPS shipping applies to any box with a cubic area equivalent to or larger than 1,728 inches. To figure out whether your package falls into this category, multiply height x width x depth. If your total equals or exceeds 1,728 (the number of inches in a cubic foot), your USPS shipment is subject to DIM weight pricing. USPS charges are always the greater of actual weight or DIM weight.

USPS shipping dimensional weight mailboxes

Note that DIM weight pricing doesn’t affect the costs for USPS flat rate shipping. You can still ship any weight for a fixed price, if your items fit into a flat rate box or envelope.

How to calculate DIM weight charges for USPS shipping

To calculate USPS shipping DIM weight charges, the formula is:

H x W x D/166 = DIM weight

USPS shipping for holiday ornaments dimensional weight

For example, let’s say you need to ship a box of holiday ornaments that weighs 2 pounds. Your box is 24” x 12” x 6”. Start by multiplying 24x12x6. If the total is at least 1,728, then calculate the DIM weight.

24 x 12 x 6 = 1,728

(24x12x6)/166 = 10.4

In this example, the USPS shipping DIM weight of your package is higher than the actual rate. You pay for the DIM weight, rounded up to the nearest pound. Your shipping cost would reflect the 11 pound DIM weight rather than the 2 pound actual weight.

USPS shipping books dimensional weight

What if you shipped books in the same sized box? The total weight of your package is 15 pounds. In this case, you would pay the USPS shipping cost for the actual weight of 15 pounds.

What if you could ship your holiday ornaments in a slightly smaller box? If your box is 24 x 10 x 6, that’s 1,440 cubic inches. The box comes in under a cubic foot. In this case, your parcel isn’t subject to DIM weight charges on USPS shipping. You’ll pay to ship 2 pounds.

Who Needs to Worry About DIM Weight Pricing?

If you use USPS shipping, you need to be aware of this USPS DIM weight pricing change. If your packages are smaller than 1 cubic foot or you ship heavy objects, your USPS shipping costs probably won’t change. However, if you send light objects in large boxes, DIM weight pricing could be a factor in your USPS shipping costs.

USPS shipping dimensional weight pricing

Some examples of products that are likely to be affected by DIM weight pricing are things that are more bulky than heavy. This could include products like a lightweight bike helmet. Fragile products, such as glass items or delicate sculptures, can also get hit with DIM charges. These items may need extra packaging to keep them safe during USPS shipping, so you might end up with a lightweight object in a large box.

DIM weight pricing

DIM Weight and the Major Carriers

Both of the other major carriers, UPS and FedEx, also use DIM weight pricing. So, you won’t be able to escape DIM weight charges by switching from the USPS. However, the carriers have different DIM factors, and that can affect what you pay for oversize packages.

Let’s look at the example from above, the box of ornaments that weighed 2 pounds. Using the DIM factor of 166 for USPS shipping, you had to pay for 11 pounds. FedEx has a DIM factor of 139. The lower the DIM factor, the higher your costs. 

The formula to ship the ornaments by FedEx looks like this:

(24x12x6)/139 = 12.4

Thus, you would pay for 13 pounds if you shipped that package via FedEx.

UPS uses two DIM factors: 139 for daily rates and 166 for retail rates. Daily shippers are high volume UPS users. These shippers usually have a daily scheduled pickup. Retail shippers are everyone else. If you ship an occasional package by UPS, you will pay retail rates.

UPS has heavier DIM weights for its daily shippers than its retail shippers. However, UPS’s daily rates are lower than its retail rates, so a daily shipper might still pay a lower rate.

This illustrates another factor to consider when you calculate DIM weight shipping. Consider the rate that each carrier will charge you to deliver your package. The largest DIM weight may not always translate to the highest shipping cost. This is particularly true if one carrier starts out with a lower rate. Use Red Stag Fulfillment’s DIM weight calculator to compare carrier pricing.

Should You Ship by USPS?

USPS shipping is a still a great option, especially around the holidays. Plus, if you’re aware of DIM weight charges, you can take steps to mitigate them.

For example, instead of shipping 2 pounds of holiday ornaments in a large box, you could divide your USPS shipment into two smaller boxes. If each box is under 1 cubic foot, you might pay less to ship two small boxes than one large box. 

Another way to avoid or reduce DIM weight charges is to use the smallest possible box to ship your items. Using a huge box surrounded by a large amount of infill isn’t the only way to safely ship fragile products. Fulfillment companies have developed innovative ways to pack and ship orders in the smallest possible box. Products that fit snugly in a box that’s just the right size need less infill to ship undamaged. 

USPS shipping dimensional weight Red Stag box machine

Red Stag Fulfillment uses a box-making machine that calculates the exact dimensions needed for each order. Then the machine creates a custom box to fit the order exactly. That’s just one of the ways that an order fulfillment company can save you money. If you are an eCommerce seller, working with a fulfillment warehouse gives you the benefit of packing and shipping expertise and frees up your time to work on your business.