A practical guide for importers, ecommerce sellers, creators shipping samples, and small teams comparing courier or freight quotes. It explains the difference between actual weight, dimensional weight, volumetric weight, CBM, and chargeable weight.
The short answer
Shipping weight is not always the weight you see on a scale. For courier and many air freight services, carriers usually compare actual weight with dimensional weight. The higher number becomes the chargeable weight estimate.
Dimensional weight = Length x Width x Height / divisor
For many air express estimates, use centimeters and a divisor such as 5000.
Example: a carton measuring 50 x 40 x 30 cm has a dimensional weight of 50 x 40 x 30 / 5000 = 12 kg. The same carton has a CBM of 50 x 40 x 30 / 1,000,000 = 0.06 CBM. CBM and kilograms are different units, so do not mix them.
Actual weight vs dimensional weight vs chargeable weight
Actual weight
Actual weight is the packed package weight measured on a scale. For sourcing from China, this should include the product, inner packing, carton, foam, inserts, labels, and any protective material.
Dimensional or volumetric weight
Dimensional weight turns package volume into a billing weight. It exists because a large but light carton uses aircraft, van, warehouse, and sorting space.
Chargeable weight
Chargeable weight is the number used for a cost estimate. It is commonly the higher of actual weight and dimensional weight, sometimes rounded up according to carrier rules.
Step-by-step workflow
- Ask the supplier for packed carton dimensions, not only product size.
- Ask for gross weight per carton and number of cartons.
- Confirm the divisor from the courier, air freight agent, or forwarder.
- Calculate dimensional weight for each carton group.
- Compare actual weight and dimensional weight.
- Use the higher number as the estimated chargeable weight.
- Check whether the quote has minimum billable weight, remote area fee, oversized fee, fuel surcharge, or pallet rules.
Practical China sourcing example
A buyer in the United States asks a Zhangjiagang supplier to quote a sample shipment. The factory says the sample box is 45 x 35 x 25 cm and weighs 3 kg after packing. With a 5000 divisor, the dimensional weight is 45 x 35 x 25 / 5000 = 7.88 kg. Even though the scale weight is only 3 kg, the quote may be based on about 7.9 kg or rounded higher.
This is why a buyer should ask for dimensions early, not only product weight. If the packaging can be safely reduced, the shipping quote may drop without changing the product itself.
Common mistakes
- Using product dimensions instead of final packed carton dimensions.
- Using net product weight instead of gross packed weight.
- Mixing CBM with dimensional weight.
- Using the wrong divisor for the shipping method.
- Forgetting to multiply by carton quantity.
- Ignoring pallet dimensions when goods are palletized.
- Comparing freight quotes without checking whether both quotes use the same divisor and rounding rule.
Which calculator should you use?
Use the main shipping calculator when you need one quick answer. Use the specialized tools when your search intent is more specific.
FAQ
Is shipping weight the same as package weight?
Not always. Package weight often means actual packed weight. Shipping weight may mean chargeable or billable weight after dimensional weight is compared with actual weight.
What divisor should I use?
Use the divisor from your carrier, courier, marketplace logistics rule, or freight forwarder. A 5000 divisor is useful for many cm/kg air express estimates, but it is not universal.
Does this work for sea freight?
The volume and CBM part is useful for sea freight planning. But sea freight often uses CBM, container space, minimum charges, port fees, and route-specific rules, so confirm with your forwarder.
Can packaging changes reduce shipping cost?
Yes. If dimensional weight is higher than actual weight, reducing outer carton size can sometimes lower the chargeable weight. Never reduce protective packaging so much that product damage becomes likely.
Disclaimer
This guide and the related calculators provide practical estimates for planning and communication. They are not legal, customs, tax, or freight advice. Always confirm final rates and rules with the carrier, freight forwarder, customs broker, or marketplace logistics provider.
More shipping weight articles
Use these practical articles when you need to understand why shipping weight, dimensional weight, carton dimensions, and chargeable weight affect the final quote.
Actual vs dimensional weightAsk supplier for carton dataCourier vs air freightFreight quote checklist