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Dimensional weight can affect what your business pays to ship lightweight, bulky packages. Learn how dimensional weight works, how to calculate it, and which formulas apply to Purolator, UPS, FedEx, Canpar, DHL and GLS shipments.
Knowing how to calculate dimensional weight is important when shipping packages because couriers may price a shipment based on the space it occupies, not only its actual scale weight. A lightweight but oversized box can therefore cost more to ship than its physical weight alone might suggest.
Dimensional weight, also called DIM weight, is calculated using the package’s length, width, and height along with the dimensional divisor that applies to the courier and service selected. Because those divisors can vary by carrier and service type, using the correct formula is essential when estimating shipping costs.
What Is Dimensional Weight?
Dimensional weight is a calculated shipping weight based on the amount of space a package occupies in a courier’s delivery network.
Couriers generally compare the package’s dimensional weight with its actual weight when determining the applicable billable weight. This is why accurate package dimensions are just as important as accurate scale weight when creating a shipment.
A large box containing a lightweight product, for example, may have a dimensional weight that is significantly higher than its actual weight.
When creating a shipment through FlagShip’s online shipping system, enter the package’s actual dimensions and weight accurately so the system can calculate the available courier rates based on the shipment information provided.
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Sign up for a free FlagShip account to compare discounted rates from multiple couriers in one place.
Quick Summary: How to Calculate Dimensional Weight
Dimensional weight helps couriers account for the amount of space a package occupies, not just how much it weighs. Here are the key points businesses should know:
- Measure accurately: Record the package’s length, width, and height after it has been fully packed.
- Use the correct divisor: Dimensional-weight divisors vary by courier and, in some cases, by service type.
- Calculate DIM weight: Multiply length × width × height, then divide by the applicable courier divisor.
- Check the service: Air and ground services can use different formulas, particularly with Purolator, UPS, DHL and GLS.
- Avoid unexpected adjustments: Incorrect dimensions or weight can result in billing adjustments after the courier measures the package.
How to Calculate Dimensional Weight
The basic dimensional-weight calculation is:
Dimensional Weight Formula
Length × Width × Height ÷ Dimensional Divisor = Dimensional Weight
The divisor depends on the courier, service type, and whether your package measurements are entered in inches or centimetres.
For example, if a courier service uses a divisor of 139 for measurements in inches:
Length × Width × Height ÷ 139
If the corresponding metric divisor is 5000:
Length × Width × Height ÷ 5000
Always use the divisor that applies to the specific courier and service you are shipping with.
Dimensional Weight Formulas by Courier
The following dimensional-weight formulas apply to the courier services listed below:
| Courier | Service | Formula – Inches | Formula – Centimetres |
|---|---|---|---|
| Purolator | Air Services | L × W × H ÷ 115 | L × W × H ÷ 4100 |
| Ground Services | L × W × H ÷ 139 | L × W × H ÷ 5000 | |
| UPS | Domestic Air Services | L × W × H ÷ 115 | L × W × H ÷ 4100 |
| All Other Services | L × W × H ÷ 139 | L × W × H ÷ 5000 | |
| FedEx | Domestic Air Services | L × W × H ÷ 139 | L × W × H ÷ 5000 |
| Ground Services | L × W × H ÷ 139 | L × W × H ÷ 5000 | |
| Canpar | Air Services | L × W × H ÷ 139 | L × W × H ÷ 5000 |
| Ground Services | L × W × H ÷ 139 | L × W × H ÷ 5000 | |
| DHL | Air Services | L × W × H ÷ 139 | L × W × H ÷ 5000 |
| Ground Services | L × W × H ÷ 166 | L × W × H ÷ 6000 | |
| GLS | Air Services | L × W × H ÷ 115 | L × W × H ÷ 5000 |
| Ground Services | L × W × H ÷ 139 | L × W × H ÷ 6000 |
Important Note for Purolator Shipments
If your shipment is not a long haul, such as Toronto to Montreal, even though the quote may say Express, the shipment will travel by ground and the Ground Service dimensional-weight rate will apply.
For a long-haul shipment, such as Toronto to British Columbia, you may have the option to choose Ground or Express. If you choose Express and the shipment travels by air, the Air Service dimensional-weight rate will apply.
Dimensional Weight Divisors at a Glance
For a faster reference, the table below shows the dimensional divisors used in the formulas above.
| Courier / Service | Inches Divisor | Centimetres Divisor |
|---|---|---|
| Purolator Air | 115 | 4100 |
| Purolator Ground | 139 | 5000 |
| UPS Domestic Air | 115 | 4100 |
| UPS All Other Services | 139 | 5000 |
| FedEx Air & Ground | 139 | 5000 |
| Canpar Air & Ground | 139 | 5000 |
| DHL Air | 139 | 5000 |
| DHL Ground | 166 | 6000 |
| GLS Air | 115 | 5000 |
| GLS Ground | 139 | 6000 |
Example: Calculating Dimensional Weight
Suppose your packed box measures:
- Length: 20 inches
- Width: 15 inches
- Height: 10 inches
The package volume is:
20 × 15 × 10 = 3,000 cubic inches
If the applicable courier service uses a divisor of 139:
3,000 ÷ 139 = 21.58 lb
The dimensional weight is approximately 21.6 lb before any carrier-specific rounding rules are applied.
This demonstrates why entering accurate dimensions matters. A package can be physically lightweight while occupying enough space to produce a significantly higher dimensional weight.
Why Dimensional Weight Matters for Your Shipping Costs
Dimensional weight can have a direct impact on the cost of shipping bulky or lightweight products.
| Shipping Factor | Why It Matters |
|---|---|
| Oversized Packaging | A box that is much larger than the product inside can increase dimensional weight unnecessarily. |
| Incorrect Measurements | If package dimensions are entered incorrectly, the courier may remeasure the shipment and apply a billing adjustment. |
| Courier Selection | Different couriers and service levels can use different dimensional divisors, affecting the calculated DIM weight. |
| Service Selection | Air and ground services may use different formulas, so the selected service can affect dimensional weight. |
How to Reduce Dimensional Weight Charges
You cannot change a courier’s dimensional divisor, but you can reduce unnecessary dimensional weight by improving how your products are packed.
- Choose appropriately sized boxes: Avoid excessive empty space around the product.
- Measure after packing: Use the final outer dimensions of the ready-to-ship package rather than the dimensions of the product itself.
- Enter accurate measurements: Measure length, width, and height carefully before creating your shipment.
- Compare courier services: Different carrier and service combinations may produce different shipping costs. FlagShip allows businesses to compare available courier rates in one place.
- Review your packaging regularly: Businesses that ship the same products repeatedly may be able to reduce package size by changing box sizes or internal packing materials.
Using FlagShip to Calculate Your Shipping Rate
You do not need to calculate every shipment manually before obtaining a courier quote.
When creating a shipment through FlagShip’s online shipping system, enter the package’s actual weight and accurate dimensions. The system uses the shipment details to return available courier rates and services.
Because different carriers can apply different dimensional-weight formulas, comparing courier options can help your business evaluate the combination of cost, service, and transit time that works best for each shipment.
FlagShip provides access to Purolator, UPS, FedEx, Canpar, DHL and GLS through one account.
Frequently Asked Questions About Dimensional Weight
Dimensional weight, or DIM weight, is a calculated shipping weight based on a package’s length, width, and height. It helps account for the amount of space a package occupies in a courier’s delivery network.
Multiply the package length by its width and height, then divide the result by the dimensional divisor that applies to the courier and service being used: Length × Width × Height ÷ Divisor.
No. Dimensional divisors can vary by courier and service. For example, the formulas used for Purolator Air and Ground services differ, and UPS also uses different divisors for Domestic Air Services and other services.
Yes. Ground services can use dimensional-weight calculations. The applicable divisor depends on the courier and service being used.
If the courier measures a different package weight or dimensions than those entered when the shipment was created, the shipment may be adjusted based on the courier’s measurements and applicable rating rules. Accurate package information helps reduce the risk of unexpected billing adjustments.
When you enter the package weight and dimensions into FlagShip’s online shipping system, the shipment information is used to calculate and display available courier rates. Accurate dimensions and actual weight should always be entered when creating the shipment.
FlagShip provides access to Purolator, UPS, FedEx, Canpar, DHL and GLS, allowing businesses to compare available courier options through one account.
Accurately calculating dimensional weight helps businesses understand how package size can affect shipping costs and reduces the risk of unexpected courier adjustments.
With FlagShip, you can compare available courier rates, manage shipments through one platform, and access discounted business shipping options from leading couriers.
If you have any questions about dimensional weight or your shipment, contact our support team at [email protected] or call us toll-free at 1-866-320-8383.
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