When your package is large but not that heavy, it could get charged based on its dimensional weight (or DIM weight) instead of its actual weight 🙈
This typically happens when you ship large but lightweight packages, such as wreaths, handbags, or stuffed animals that take up valuable cargo space in the back of trucks and planes. However, it can also happen with smaller lightweight packages, depending on their size and which service you use.
What is dimensional weight?
Understanding dimensional weight (DIM): Dimensional weight, or DIM, is a pricing method where carriers charge based on how much space a package takes up rather than its actual weight 📦
How DIM is calculated: Carriers calculate dimensional weight using your package’s dimensions. If the package meets certain criteria, they charge whichever is higher: the dimensional weight, or the actual weight of your shipment.
Pirate Ship automatically calculates and applies your package's DIM weight
We automatically display DIM weight pricing if it applies: If your package details trigger dimensional weight pricing when making labels or comparing rates, our software will automatically display those prices. In other words, Pirate Ship does the work for you 😉
This means there is no need for you to calculate the DIM Weight of their package and try to factor it in yourself. Our system already does this.
When does DIM weight apply?
The specific criteria for when DIM weight applies changes slightly from carrier to carrier.
USPS
With USPS, you'll be charged DIM weight pricing if your shipment meets all the following criteria:
Its dimensional weight is greater than its actual weight
Its volume is greater than 1 cubic foot (1,728 cubic inches)
You're using weight-based Priority Mail, Priority Mail Express, or USPS Ground Advantage (DIM weight doesn't apply to international USPS shipments)
If you meet none or only some of these criteria, you'll be charged based on your shipment's actual weight 🎉
UPS
All UPS services, both domestic and international, are potentially subject to dimensional weight pricing.
When using UPS Ground or 3 Day Select, you'll be charged for DIM weight if:
Your shipment's dimensional weight is greater than its actual weight
Its volume is greater than 1 cubic foot (1,728 cubic inches)
For all other UPS services, including all international services, you'll only be charged for DIM weight if:
Your shipment's dimensional weight is greater than the actual weight
Reminder: Pirate Ship calculates DIM weight for you
You don't need to calculate DIM weight: As a reminder, Pirate Ship automatically calculates and charges for DIM weight pricing any time it applies. You don't need to do any math if you don't want to, but in case you do, the next section sheds light on how to calculate DIM weight.
How to calculate DIM weight
The DIM weight formula: To determine a package's DIM weight, carriers utilize the following formula:
(Length x Width x Height) / 166 or 139
The result (rounded up to the nearest whole pound) is the DIM weight of the package. Once this is determined, carriers apply DIM weight pricing based on the criteria listed in the section above.
Why are there two different divisors?
Domestic DIM weight divisor: Both USPS and UPS use 166 as their DIM weight divisor for domestic shipments.
International DIM weight divisor: For international UPS shipments, use 139 as the divisor in the DIM weight equation (the only exception is UPS Standard parcels going to Canada; UPS uses 166 as the DIM weight divisor for those shipments).
DIM weight pricing can come as Carrier Adjustments to your account
DIM weight and Carrier Adjustments: Even though Pirate Ship automatically calculates DIM weight pricing, there may be situations when DIM charges are applied to your account as Carrier Adjustments.
Carrier Adjustments happen when UPS and USPS determine that your package has different weights and/or dimensions from what you entered when you purchased your label. They then charge you (or, in rare cases, credit you) for the difference in postage after you ship your package.
Learn more about carrier adjustments that get applied to your account.
How can I avoid DIM weight pricing?
Here are some strategies to avoid DIM weight pricing:
Optimize packaging size: Use the smallest packaging possible for the item you're sending
Cutting boxes: See if you can cut your box down to a smaller size
Use multiple boxes: If possible, separate the items being sent into multiple, smaller shipments
Use the "Box in a Bag" method: If the box can fit inside of an envelope or poly mailer with room to spare, see if you can find a lower rate through the "box in a bag" trick
The "box in a bag" method is a strategy of putting your box inside a loose-fitting poly mailer to qualify for USPS Priority Mail Cubic rates