When sending a package to customers, a shipper is trying to accomplish several goals: get it to the customer on time, get it to the customer in good condition, and get it to the customer at a reasonable price. The world of shipping is incredibly complex, and determining the cost to ship each package sometimes seems to require a PhD. Instead of just measuring the package size and weight to know determine the price, one other factor major carriers use is dimensional weight pricing. FedEx dimensional (DIM) weight has changed in the last few years.

Here’s what you need to know about FedEx dimensional weight and ship rates.

Calculating Dimensional Weight

Dimensional weight determines a package’s density rather than just its actual size or weight. That DIM weight reflects the amount of space the package will occupy in transit, compared to its physical weight. Think about it in terms of package volume, the space it takes in the truck or plane, in addition to the weight of that volume.

The simplest way to understand a package’s dimensional weight calculation is to weigh the physical package, including its contents and packaging materials. Physical weight pricing does not involve measuring the package in any way – it’s purely how many pounds the package weighs on the scale.

The dimensional weight calculation uses a formula to determine the DIM weight. That formula rounds each measurement to the nearest whole inch. If it is less than half an inch, the number will be rounded down, and if it’s more than half an inch, it will be rounded up. This is the DIM weight formula:

DIM weight = package length in inches x package width in inches x package height in inches / DIM divisor

The DIM divisor is a set number specific to each carrier (though it can be the same number). It is considered the base weight of 1 cubic foot of space, or 1,728 cubic inches. Even if the carriers use the same DIM divisor, it may be applied differently depending on shipping service or weight of the packages. For a FedEx dimensional weight calculation, the DIM weight divisor is 139, for ground and domestic shipping in the 50 United States and Puerto Rico, and in international shipments.

The DIM weight is used as the billable weight if it’s higher than the physical weight. FedEx recommends these steps to determine which weight would be used.

  • Calculate the DIM weight, or cubic size, by multiplying the length, height and width in whole inches. Then divide that by 139.
  • Calculate the actual weight of the packages using a scale, increasing fractional numbers to the next whole pound.
  • Compare the DIM weight to the actual weight, and the larger one would be used for rate calculation.
  • For multiple packages in the shipment, include the total billable weight of the packages.

For example, if you are shipping a package that is 20 x 12 x 6 inches, the cubic volume is 1,440 cubic inches, and it’s divided by 139 for a dimensional weight of 11 pounds (rounded up). The DIM weight will be used as a billable weight unless the actual package weight is 12 pounds or more.

Pros and Cons of DIM Weight

Carriers want to maximize space on their vehicles. Using DIM weight as the pricing factor encourages shippers to reconsider their packaging, so they are increasing their efficiency and using less space. The practice discourages shippers from including too much lightweight packaging materials or air in their parcels, if possible. Carriers can then fit more packages in their vehicles. Shippers can potentially decrease shipping costs by increasing packaging efficiency.

The good news for your company is if it ships high-density goods, you may be paying less than you would pay with strictly weight-based pricing.

Of course, the use of dimensional weight has not had a net zero effect in pricing. Prices have gone up, as e-commerce has greatly increased the quantity of shipping in the United States and abroad. While FedEx has been using DIM pricing for air express for a while, it introduced dimensional weight for freight and ground shipping in late December, 2014. Experts estimated that shippers who didn’t adjust their packaging would see shipping cost increases of 5 to 25%. Those shipping lightweight but bulky packages would be hit the hardest.

How Dimensional Weight Use Differs Between FedEx® Services

FedEx services used DIM weight differently, and the FedEx Service Guide spells out the rules.

FedEx Express

Any shipments in the customer’s own packaging will use DIM weight. It also can apply to FedEx packaging. A minimal billing weight applies for all FedEx Express shipments. For U.S. shipments, applying dimensional weight is on a per-package and a per-shipment basis. For shipments to Puerto Rico and international destinations, DIM weight applies per shipment. If the DIM weight is higher than the actual weight, DIM weight will be used.

FedEx Ground

For FedEx Ground, applying dimensional weight is for all shipments on a per-package basis. If the DIM weight is higher than the actual weight, DIM weight will be used. If the package weighs more than 150 pounds, a prorated per-pound rate will be used. Package dimensions and shape may change during transit, which can affect the package’s dimensional weight and surcharge eligibility. If the package dimensions change during transit, FedEx may make appropriate adjustments to the bill of lading, or shipping charges, at any time.

FedEx Home Delivery

If the residential delivery package has a DIM weight greater than 70 pounds, it’s handled the same as a FedEx Ground package with the same DIM weight shipped under the same circumstances. There are also FedEx Home Delivery fees for residential delivery, and other related shipping charges.

FedEx Express Freight

DIM weight is only applied on a per-freight handling unit. If the DIM weight is higher than the actual weight, DIM weight will be used. A minimal billable weight applies.

FedEx International Priority Freight

DIM weight is used on a per-shipment basis.

FedEx International Economy Freight

DIM weight is used on a per-shipment basis.

FedEx SmartPost

SmartPost, a joint service offered with the U.S. Postal Service, uses DIM rating.

The higher weight (DIM or actual weight) will be used as the billable weight to calculate ship rates for import-rated international shipments to the U.S., and U.S. export shipments.


How to Lower FedEx® Dimensional Weight Prices

Shippers are smart to consider pricing of their shipping services, and determine how to lower FedEx ship rates they’re paying. The system can seem unfair if paying for DIM weight when the physical weight rate is lower. Spending some time determining how to decrease those costs can pay off in both the short run and the long run, especially if shipping dense packages.

It’s time to make friends with the FedEx DIM weight calculator, which helps you determine the DIM weight so you can better understand your options.

Step back and evaluate what you’re shipping.

  • If you’re shipping lightweight items, can you decrease the packaging sizes?
  • Can you ship the items in multiple boxes or send the item unassembled?
  • Can you rearrange the parts inside to better utilize the space?
  • Can you vacuum seal the contents to reduce the air inside?

The goal is to decrease the package sizes as much as possible, without sacrificing package integrity. Play around with the box size, as even decreasing it by an inch might decrease the shipping cost. Using different filler material, that doesn’t bulge or expand, can help as well. After all, the larger your package volume, the larger its dimensional weight. Maybe you can use bubble or poly mailers instead of boxes, which lowers the weight and packaging sizes.

FedEx and their Package Testing and Design Lab can even help you find better packaging solutions, at no cost to you.

If you can’t shrink your package down to a reasonable DIM weight, consider the goods you’re shipping. It may be a better business practice not to sell certain items if the shipping costs are not going to be profitable for your business. Consider changing the mix of goods you sell to goods with better DIM weights and fewer FedEx surcharges, unless the customer is willing to pay the higher prices. Explaining to customers how DIM weight works may make them more willing to pay the higher prices.

Negotiating Ship Rates

One other way to lower shipping costs is to negotiate pricing with FedEx. Some companies do this themselves, however professionals with a greater understanding of the total market can usually get better pricing. Some of the factors which a shipper may be able to negotiate with FedEx include:

Cubic threshold: If you can increase the cubic threshold, you can increase the space you need without raising costs.

DIM factor: The 139 divisor might be negotiable depending on your shipping volume and other variables. The larger the denominator, the number below the line, the smaller the DIM weight output will be. FedEx’s 2015 divisor was 166. Since then, it’s dropped to 139, costing its customers more money.

Incentives: If the DIM weight factors can’t be changed, the carrier may be willing to negotiate on other discounts and services, like surcharges.

FedEx is only one carrier using DIM weights for pricing. Increasingly, freight companies are using them as well, especially for LTL (less-than-truckload) shipments. DIM weight pricing is not going away any time soon, so it’s important to get the best pricing you can by evaluating your shipping factors, and negotiating the best prices.


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