What is volumetric weight?

#ecommerce packaging

Volumetric weight determines how carriers price your shipments based on package size rather than just mass. Understanding it is one of the most direct ways to reduce your logistics and packaging costs.

In this article, we’ll cover:

What volumetric weight is and why carriers use it
How to calculate volumetric weight using the DIM factor formula
How volumetric weight compares to actual (gross) weight
Carrier DIM factor differences and how they affect your costs
How to reduce your shipping costs by optimising your packaging
Frequently asked questions about volumetric and dimensional weight

What is volumetric weight in shipping?

Volumetric weight is a method for calculating the chargeable weight of a package based on volume rather than gross weight. It takes into account the total space a package occupies in a delivery vehicle, not just its weight.

Carriers use this figure because a large, lightweight parcel takes up space that could otherwise carry revenue-generating freight. By pricing on whichever is greater, the volumetric weight or the gross weight, carriers ensure each cubic centimetre of vehicle capacity earns its keep.

This pricing model applies across all transport modes. Whether your goods travel by lorry, ship or plane, the same logic holds. It also applies to return shipments. If you offer free shipping and returns, the same pricing applies to every item returned. If your volumetric weight is high relative to the gross weight, you could be making a loss on each return.

How to calculate volumetric weight: formula and examples

The volumetric weight formula is straightforward. Multiply the length, width and height of your package in centimetres, then divide by the DIM factor.

The DIM factor explained

The DIM factor (also called the dimensional factor) is a divisor set by each carrier to convert cubic size to a comparable weight figure. For centimetre measurements, most carriers use a DIM factor between 5,000 and 7,000. For inch measurements, the equivalent figure is typically 305.

The formula written out in full:

Volumetric Weight (kg) = (Length cm x Width cm x Height cm) / DIM Factor

The carrier then charges whichever is greater: the volumetric weight or the package’s actual gross weight.

Step-by-step volumetric weight calculation

Here are two worked examples using a DIM factor of 5,000.

Example 1: Light and bulky package

Dimensions: 50 x 30 x 30 cm

Gross weight: 3 kg

Calculation: (50 x 30 x 30) / 5,000 = 45,000 / 5,000 = 9 kg volumetric weight

Because 9 kg is greater than 3 kg, the carrier charges are based on volumetric weight. You pay for 9 kg of freight even though the package weighs only 3 kg.

Example 2: Heavy and compact package

Dimensions: 30 x 30 x 20 cm

Gross weight: 10 kg

Calculation: (30 x 30 x 20) / 5,000 = 18,000 / 5,000 = 5.4 kg volumetric weight

Because 5.4 kg is less than 10 kg, the carrier charges on the gross weight. You pay for 10 kg.

Volumetric weight calculation quick-reference table

Package type	Dimensions (cm)	Gross weight	Volumetric weight (DIM 5,000)	Charged on
Light and bulky	50 x 30 x 30	3 kg	9 kg	Volumetric weight
Heavy and compact	30 x 30 x 20	10 kg	5.4 kg	Gross weight

Volumetric weight vs actual weight: which are you charged?

The rule is simple. Carriers charge on whichever figure is higher.

If your package is light but large, it will be charged based on its volumetric weight.
If your package is small and heavy, it will be charged based on its gross weight.

This is the core of the dimensional weight pricing model. It exists because a lightweight parcel that fills half a pallet is just as costly to a carrier as a dense, heavy one. Pricing on gross weight alone would make oversized, lightweight freight unprofitable to transport.

When gross weight takes priority

Gross weight takes priority when the actual weight of the package exceeds its calculated volumetric weight. Dense goods, such as machinery components, bottled liquids or metal parts, typically fall into this category. For these shipments, the freight density is high enough that the carrier recovers its costs solely through the weight charge.

For most e-commerce packaging, however, the opposite is true. Clothing, homeware, electronics accessories and similar goods often ship in boxes far larger than the product inside. This is where volumetric pricing has the greatest impact on your costs.

Carrier DIM factor policies: how they differ

Different carriers apply different DIM factors, so the same package can have a different chargeable weight depending on who ships it. The table below shows typical DIM factors used by major carriers. Always check directly with your carrier for their current rate, as these figures can change.

Carrier	Typical DIM factor (cm)	Notes
UPS	5,000	Standard for international parcels
FedEx	5,000	Applied to express and economy services
Royal Mail	Varies by service	Some services use volumetric pricing bands rather than a single DIM factor
DHL	5,000	Standard international metric
General freight	5,000–7,000	Range varies by contract and volume

The DIM factor range of 5,000 to 7,000 means a carrier using 7,000 will produce a lower volumetric weight from the same package than one using 5,000. If you’re negotiating a contract, the DIM factor is a lever worth discussing alongside the per-kilogram rate.

Why does volumetric weight exist?

Volumetric weight exists because delivery vehicles have two constraints: weight capacity and cubic capacity. A lorry might be able to carry 20 tonnes, but its cargo space could fill up with lightweight, bulky goods long before it reaches that weight limit.

The more efficiently a vehicle is loaded, the lower the carrier’s cost per parcel. If carriers priced purely on gross weight, a lorry full of pillow boxes or inflated mailers would be deeply unprofitable. Dimensional weight pricing balances the books by making sure every parcel contributes fairly to the cost of the journey.

This is also why the DIM factor exists. It converts a package’s three-dimensional size into a single weight figure. The carrier then charges on whichever figure, volumetric or gross, better reflects the true cost of carrying that parcel.

How to reduce shipping costs by optimising package dimensions

The most direct way to reduce your volumetric weight charge is to reduce the empty space inside your packaging. A box that fits your product closely results in a lower volumetric weight and lower shipping costs.

Here are four practical steps to get started.

Audit your current box range. Measure the dimensions of your most frequently shipped products and compare them to the boxes you’re using. A product that fits a 30 x 20 x 15 cm box, shipped in a 50 x 30 x 30 cm box, is generating unnecessary volumetric weight.
Use the right void fill. When you do need a larger box for protective reasons, use appropriate void fill to prevent movement. This protects the product without encouraging you to oversize the packaging further.
Review your packaging for returns. If you offer free returns, the volumetric weight of returned goods is a real cost. Consider whether your returns packaging can be right-sized or whether a returns-specific pack format could reduce that cost.
Negotiate your DIM factor. If you ship at volume, ask your carrier what DIM factor applies to your account. A higher DIM factor means a lower volumetric weight for the same package size.

Our packaging specialists can review your current packaging range and identify opportunities to right-size to reduce your chargeable weight. Contact us today to discuss your product range and packing operation.

Putting it into practice

Volumetric pricing affects almost every business that ships parcels. Whether you’re sending one box a day or thousands a week, understanding how your carrier calculates the chargeable weight gives you the information you need to reduce unnecessary costs.

The formula is simple: length x width x height, divided by the DIM factor. If the result is higher than your gross weight, that’s what you pay on. The fix is equally straightforward: reduce the size of your packaging and your volumetric weight comes down with it.

Speak to our Packaging Specialists on 0800 542 44 28 or at sales@rajapack.co.uk to find the right packaging for your products and shipping requirements.

Key takeaways

Volumetric weight is calculated by multiplying a package’s length, width and height in centimetres, then dividing by the DIM factor (typically 5,000 for metric measurements).
Carriers charge on whichever is greater: the volumetric weight or the actual gross weight of the package.
A light and bulky package will be charged on its volumetric weight; a heavy and compact package will be charged on its gross weight.
The DIM factor varies between carriers and can range from 5,000 to 7,000, so the same package may attract a different chargeable weight depending on your courier.
Reducing unnecessary empty space in your packaging is the most direct way to lower your volumetric weight and your shipping costs.

FAQ: volumetric weight and dimensional pricing

Volumetric weight is a pricing method carriers use to calculate a package’s chargeable weight based on its size rather than its actual mass. It ensures that large, lightweight parcels contribute their fair share to transportation costs.

How is volumetric weight calculated?

Multiply the length, width and height of your package in centimetres, then divide by your carrier’s DIM factor. For example, a 50 x 30 x 30 cm package divided by 5,000 gives a volumetric weight of 9 kg.

What is a DIM factor in shipping?

The DIM factor is a divisor used by carriers to convert a package’s cubic volume into a comparable weight figure. Most carriers use a DIM factor of 5,000 for centimetre measurements, though this can range from 5,000 to 7,000 depending on the carrier and service.

What is the difference between volumetric weight and actual weight?

Actual (gross) weight is the weight the package registers on a scale. Volumetric weight is a calculated figure based on the package’s dimensions. The carrier charges whichever is higher.

Does volumetric weight apply to return shipments?

Yes. If you offer free returns, the same dimensional weight pricing applies to all items returned. If your packaging is oversized relative to the product, you may be paying an inflated volumetric rate for returns and outbound deliveries.

How can I reduce my volumetric weight?

Use packaging that fits your product as closely as possible. Reducing the length, width or height of your box directly reduces the volumetric weight calculation. Our Packaging Specialists can help you identify the right box sizes for your range.

Which carriers use volumetric weight pricing?

Most major carriers, including UPS, FedEx, DHL and Royal Mail, apply some form of dimensional weight pricing. The specific DIM factor and the services it applies to vary by carrier, so it’s worth confirming the details with your account manager.

What DIM factor should I use to calculate my shipping costs?

Use the DIM factor specified in your carrier contract. If you don’t have a negotiated rate, 5,000 is the most commonly applied standard for metric (centimetre) measurements. For inch measurements, use 305 as the equivalent figure.