How to calculate Dimensional Weight?
Hisuper HernándezShare
When shipping packages, you might encounter a situation like this: your package weighs 10 kg, but you're charged 20 kg. This is because logistics companies compare the volumetric weight with the actual weight and charge rates based on the greater of the weight.
If your shipments are lightweight but take up a lot of space, you'll be charged by volumetric weight. It's essential to know what volumetric weight is and how to calculate it. This will affect your freight costs.
In today's post, I explain volumetric weight in a practical way. Let's get started!
What is volumetric weight or DIM weight?
Volumetric weight = Weight per volume = Cubic weight = DIM weight = Dimensional weight
Volumetric weight is the virtual weight of the shipment, calculated by converting volume. It is used to charge shipping rates for lightweight but oversized goods.
Suppose there are two batches of goods: 15 kg of ironing equipment and 15 kg of clothing. The latter takes up much more space. To transport goods with the same gross weight, a higher charge should be made for the one that takes up more space, as the carrying capacity for transport equipment is limited. This is similar to paying more for additional seats when booking airline tickets.
Logistics companies would then measure the package size of the garments (60 x 50 x 40 cm) to calculate the total volume and convert it into volumetric weight (24 kg) to charge fees and cover the additional operating cost.
Volumetric weight vs. actual weight
Actual weight is the total actual weight of the merchandise, including packaging. In other words, it's the gross weight shown on the scale.
Compare the actual weight with the dimensional weight and you will find that,
- Actual weight ＞ volumetric weight. Freight will be charged based on actual weight. These products are called heavy or high-density products.
- Actual weight < volumetric weight; freight will be charged based on volumetric weight. These lightweight but large products are called lightweight or low-density products.
Therefore, it is clear to us that to calculate the cost of freight, known as billable weight or invoice weight, the higher of the two is used.
Generally, lightweight products are invoiced by volumetric weight. Common examples include clothing, comforters, shoes, handbags, suitcases, hoodies, stuffed animals, paper goods, etc.
When a batch of goods is composed of heavy and light products, the billable weight will be the total actual weight or the dimensional weight of that batch, whichever is greater.
What is the formula for calculating dimensional weight?
There are two ways to calculate dimensional weight: one is the total shipment volume / DIM factor, and the other is the total shipment volume in CBM * conversion rate. You can choose the method that best suits your situation. Let's analyze each one separately.
Formula 1: Dimensional Weight = Total Shipment Volume / DIM Factor
Formula to calculate the total volume of the shipment
To calculate the volume of your shipment, you must determine whether your packaging boxes are regular, irregular, or cylindrical. This affects the calculation of the package's volume.
1. For regular packages such as cubic and cuboid boxes,
Total shipping volume = (Length × Width × Height) x Quantity
Note: If the normal box swells and bulges due to the extrusion of the cargo, as shown in the following image, it will be calculated according to the longest side of the box.
Before packing your goods, measure the external dimensions of the box: Length — 15 cm; Width — 30 cm; Height — 20 cm.
Due to extrusion of the cargo or any protruding parts, please measure the package: Length — 18 cm; Width — 33 cm; Height — 22 cm.
Here the volume = L x W x H = 18×33×22
2. For irregular packages,
Total shipment volume = (Maximum length x Maximum width x Maximum height) x Quantity
3. For cylindrical packages,
Total shipment volume = (π x r² xh) x Quantity
Quick Tips
- Round each measurement to the nearest whole number. For example, 5.8 would be considered 6.
- Logistics companies measure all packages at their longest or longest point. This may be larger than the size marked on the boxes, as packages can become deformed during loading, transport, and unloading. However, the measurement deviation will not be significant; 1-2 cm is normal.
DIM Factor
A DIM factor, also known as a DIM divisor, is a number established by carriers to identify a shipment's allowable volume per unit of weight. The DIM factor varies based on different shipping methods and units of measurement. For international shipments, the most common DIM factors include:
| Using CM and KG | Using inches and pounds (Ibs) |
|---|---|
| 6000 — Air transport | 166 — Air Transport |
| 5000 — Express/Courier Shipping | 139 — Express Cargo/Courier |
In the express shipping industry, different carriers use different ratios for volume conversion. Currently, four major international express shipping giants, including FedEx, UPS, DHL, and TNT, use the DIM 5000 divisor.
Some express carriers use a divisor of 6000 or 7000. For example, Hong Kong DHL-6000 sets the number at 6000, which makes shipping low-density products more cost-effective. The higher the DIM factor, the lower the DIM weight, which generally means lower shipping costs.
Additionally, whether the shipment is domestic or international could influence the volumetric factor. For example, FedEx uses a volumetric factor of 166 for domestic packages measured in inches, while this value is 139 for international shipments.
Last but not least, DIM dividers are subject to change. We strongly recommend consulting with logistics service providers or supply agents for the most up-to-date and accurate information.
Formula 2: DIM Weight = Total Volume (CBM) * Conversion Ratio
To convert CBM to DIM weight, the ratio is:
Air transportation: 1 CBM = 167 KG
Express Cargo/Courier: 1CBM = 200KG
Ocean freight does not impose weight limits per unit of volume as strictly as express or air freight. Typically, for FCL ocean freight, it is only necessary to ensure that the cargo weight falls within the maximum payload of the containers . In the case of LCL ocean freight, , common conversion rates include:
- 1 cubic meter = 1000 kg
- 1 cubic meter = 750 kg
- 1 cubic meter = 500 kg
- 1 cubic meter = 363 kg
What conversion standards should you use? Contact us for answers, and our Jingsourcing experts will help you ship your products at the most cost-effective price.
Live example for calculating DIM weight and freight charges for courier or air shipments.
To determine the costs of shipping by courier or air, you need to calculate the DIM weight and compare it with the actual weight. The greater the weight, the billable weight.
Once you know the formula, calculating the DIM weight is easy. Here, I use two examples to show you how to calculate the DIM weight and shipping costs step by step.
Example 1: An English customer purchases a batch of diaper bags from China . This batch is packaged in 15 standard cardboard boxes, each weighing 7 kg. Shipping can be by air or through four major international express courier companies.
Step 1: Check the total gross weight
Total gross weight: 7kg * 15 = 105kg
Step 2: Measure the package and calculate the dimensional weight
You can usually find out the box size by asking your Chinese supplier directly, who will measure the package in centimeters. Here are the box measurements.
- L — 44.8 cm, which is rounded to 45 cm.
- W — 37.6 cm, which is rounded to 38 cm.
- Height — 35 cm.
Total shipping volume = (L*W*H) * quantity = (45 x 38 x 35) x 15 = 897,750 cm³ = 0.89775 m³
To calculate the DIM weight, you can divide the total volume (cm³) by the DIM factor or multiply the total volume (m³) by the conversion ratio.
If sent by express
DIM weight = 897,750 cm³ / 5000 = 0.89775 m³ x 200 = 179.55 kg.
Round up to the next half number 180 kg, as exchange rates change with every half kilogram.
If shipped by air
DIM weight = 897,750 cm³ / 6000 = 0.89775 m³ x 167 ≈ 150 kg.
Helpful Tips : For the same volume, the dimensional weight calculated for air freight is approximately 15% to 20% lower than for express freight. This is because the dimensional weight for air freight is divided by 6000, while for express freight, this figure is 5000.
Step 3: Determine the billable weight
- By express, DIM weight 180kg ＞ total gross weight 105kg.
- By air, DIM weight 150kg ＞ GVW 105kg.
In any case, the billable weight is the DIM weight.
Step 4: Calculate shipping costs
Freight costs = billable weight x freight rate.
Here we assume the freight rate is $6.5 per kg for express shipping and $5.5 per kg for air shipping.
- By express, shipping costs = 180 x 6.5 = $ 1,170
- By air, shipping cost = 150 x 5.5 = $825
Helpful Tips: Air freight is approximately 30% less expensive than express shipping. However, this does not mean that air freight is less expensive, as each shipment has a fixed cost. In practice, air freight is applied to loads over 500 kg, while express freight is applied to loads under 500 kg. Therefore, in this case, it is recommended to use express shipping, which is more cost-effective.
Example 2: An Amazon FBA seller receives a batch of shoes from China and needs to ship them to a warehouse in the western US. For this batch, 12 pairs are used per box, for a total of 40 standard cardboard boxes. Each box weighs 12 kg and measures: length: 49 cm; width: 42 cm; height: 39 cm.
In this example, we can still use the previous 4 steps for the calculation.
Actual weight: 12kg x 40 = 480kg
Calculation of total shipment volume: 49 x 42 x 39 x 40 = 3,210,480 cm³ ＝ 3.21048 CBM
Calculation of dimensional weight:
If sent by express
Gross weight (DIM) = 3,210,480 cm³ / 5000 = 3.21048 m³ x 200 = 642.096 kg. Rounded to 642.5 kg.
If shipped by air
DIM weight = 3,210,480 cm³ / 6000 = 3.21048 m³ x 167 ≈ 535.5 kg.
In any case, the billable weight is the DIM weight, which is greater than the actual weight.
As mentioned above, for loads over 500 kg, air freight is more cost-effective than express freight. Therefore, we only calculate air freight costs here.
Suppose the freight rate is $5.5 per kg for air transportation, air freight charges = 535.5 x 5.5 = $2,945.25
A bonus for you
In practice, you may hear carriers combine light and heavy packages into a single air shipment to maximize space and increase profits.
Suppose a carrier has reserved a space and collected a large quantity of heavy goods, and you need to ship a batch of large but lightweight items. In that case, the carrier will be happy to ship your products along with your heavy goods in the same shipment.
In this case, if you only ship heavy cargo, you'll waste a lot of space. But if you aggregate your cargo, you can use the available space, but it won't increase the billable weight much. Therefore, you only need to pay the airline a little more for shipping this batch of consolidated shipments, but they can charge you and other heavy cargo owners at the same time.
To receive your goods, the carrier typically offers you a 30% or 50% discount on their profit. Let's consider Example 2 and assume you agree to sacrifice 50% of your profit. This way, your billable weight is not 532 kg, but "532 - [(532 - 480) * 50%] = 506 kg." This is more economical for you.
Here you can use the following formula to obtain the final billable weight.
Final billable weight = DIM weight – [(DIM weight – actual weight) x percentage]
Live example for calculating DIM weight and freight charges for “Ocean Freight plus Courier.”
Typically, conventional LCL ocean freight is suitable for cargoes larger than 2 m3. Therefore, for Example 2, where the shipment is approximately 3.2 m3, LCL ocean freight is the most economical shipping method, regardless of delivery time .
However, if the Amazon seller can wait up to 25 days, it is recommended to use UPS Combined Ocean Freight. This solution is both cost-effective and faster than conventional ocean shipping.
In this case, we can still use the previous 4 steps to calculate the DIM weight and shipping costs.
Under the "ocean freight plus courier" shipping method, shipments are generally charged per kilogram, unlike the regular ocean freight CBM charge.
Let's assume here that the carrier offers a quote: $3.5 per kg.
Dimensional weight calculation : Total shipment volume / DIM factor = 3,210,480 cm³ / 6000 = 535.08 kg. Round up to 535.5 kg.
Since the DIM weight of 535.5kg ＞ the actual weight of 480kg, the ocean freight is charged by DIM weight.
Combined UPS Ocean Freight Shipping Cost : 535.5 x 3.5 = $1874.25
The end
By reading this, I think you'll better understand DIM weight and how it affects your shipping costs. If you have any questions, please leave a comment below.
To reduce the dimensional weight of a shipment and save money, we often simplify packaging or ship lightweight items along with other heavy items. Contact us if you need these services.
