Have you ever wondered why your shipping costs are sometimes higher than expected? One reason could be the dimensional weight of your packages. If any outbound shipment includes boxes larger than one cubic foot (length x width x height exceeds 1,728 cubic inches), you may be wasting money on excess (DIM) weight.
This article explains DIM weights and how to reduce them to save on shipping costs.
DIM weights
Dimensional weight is a pricing method used by shippers to calculate the estimated weight of a parcel instead of the actual weight. This is a way for carriers to charge for the space your package takes up on their trucks and planes, regardless of its actual weight.
To calculate, multiply the length x width x height of your package by inches and divide that total by 139 for UPS, FedEx, and DHL ground shipments or 166 for USPS Priority Mail shipments.
For example, an 18 x 18 x 18 box that actually weighs 10 pounds equals 5.832 cubic inches divided by 139 equals 42 pounds DIM weight. Or, for USPS parcel postage, the DIM weight would be 5.832 divided by 166, which equals 35 pounds. In either case, if the DIM weight is greater than the actual weight, it becomes the billable weight.

The DIM weight calculation starts with the parcel size. These parcels are 216 cubic inches (3 x 12 x 6, left) and 720 cubic inches (10 x 12 x 6). Source: eFulfillment Service.
Reduction of DIM weights
Reducing DIM weights is important for traders and consumers. By reducing the DIM weights of your packages, you can:
- Save on shipping costs.
- Offer more competitive prices to your customers.
- Reduce your carbon footprint by using less packaging materials.
There are several ways to reduce DIM weights without compromising on shipping quality.
Choose the correct box dimensions. If you’re making orders in-house, keep a wide variety of larger storage boxes to choose the smallest option for your product. In my fulfillment center, for example, we stock 22 standard sizes.
Minimize packet sizes. Think about the arrangement of the items in the box. Try to reduce package sizes by rearranging items or using specially designed packaging. Take the time to fold, flatten, stack, consolidate, vacuum seal, or otherwise minimize the amount of cardboard needed.
Consolidate shipments. Combine multiple orders into one shipment whenever possible. This will help reduce the total DIM weight of packages and save money on shipping costs.
Choose a shipping service with a larger DIM weight divider. If possible, use a shipping service with a larger DIM separator to reduce the impact of package size on shipping costs. For example, the USPS denominator is 166 versus 139 for UPS, FedEx, and DHL. For an 18 x 18 x 18 carton, that’s a DIM weight of 42 vs. 35. Alternatively, ask your fulfillment provider to assign a higher DIM divider with discounted ship rates. Again, the higher the divisor number, the lower the calculated DIM weight.
Question and Answer
- What is DIM weight? Dimensional weight is a pricing method used by shippers to compare the billable weight of a parcel against its actual weight.
- Why is it important to reduce DIM weights? Reducing DIM weights helps save shipping costs, offers customers more competitive prices, and reduces the environmental impact of shipping.
- What are the strategies to reduce DIM weights? Choose the right box dimensions, optimize package contents, consolidate shipments and increase the DIM separator.
- Can reducing DIM weights improve customer satisfaction? Yes! Reduced DIM weights and lower shipping costs allow for more competitive pricing, increasing customer satisfaction.
- How can I continuously reduce DIM weights? If you do in-house, stock a wide variety of cardboard sizes, train your staff to minimize wasted cardboard volume, and use higher DIM dividers when possible. If you are outsourcing, ask your fulfillment provider to assign a higher DIM divider.