How to Calculate Chargeable Weight

Most couriers account for both weight and volume when charging for shipments. This article will explain how the two are used and compared to determine the cost of your shipment.

What Are Volumetric Weight and Actual Weight?

Volumetric Weight and Actual weight are two key calculation methods couriers use to calculate shipping costs.

Actual weight or dead weight is simply the weight of the shipment measured in kilograms (kg) or pounds (lb).

Volumetric weight, also known as dimensional weight, is a measuring method that uses the length, width, and height to calculate a parcel's overall size and, similar to actual weight, is measured in kilograms or pounds.

Volumetric weight = (height x width x length) / dimensional factor

This dimensional factor, also known as the cubic divisor, is set differently by each courier. Most couriers use 5000 (metric units) or 139 (imperial units) as the dimensional factor.

Calculation Methods

The calculation method is determined by how the chargeable weight is calculated. Based on the shipping cost rules set by the courier, Easyship will use one of three different calculation methods to calculate the chargeable weight.

The calculation method and chargeable weight are visible in the cost breakdowns and shipment details. Below we go through the three calculation methods and the conditions that apply the method.

What Is Chargeable Weight and How Is It Calculated?

Chargeable weight is the pricing method used (higher than the actual and volumetric weight) to calculate the shipping cost of your parcel.

Example 1:

A parcel's dimensions are 50cm x 50cm x 40cm, weighs 5kg, and uses UPS Worldwide Express to ship.

Actual weight = 5kg

Volumetric weight = (50x50x40)/5000 = 20kg

Chargeable weight = 20kg

As the volumetric weight is higher than the actual weight, the chargeable weight is the volumetric weight.

Example 2: 

A parcel’s dimensions are 20cm x 15cm x 5cm, weighs 20kg, and uses FedEx International Priority to ship.

Actual weight = 20kg

Volumetric weight = (20x15x5)/5000 = 0.3kg

Chargeable weight = 20kg

As the actual weight is higher than the volumetric weight, the chargeable weight is the actual weight.

Weight Brackets

The exact chargeable weight and shipping cost are determined based on the weight bracket the chargeable weight falls under. If the chargeable weight is between two ranges, the courier will round up to the next weight bracket to determine the cost.

Weight bracket ranges are generally in 1lb or 0.5kg increments. The Chargeable Weight in Easyship will show you the weight used based on the shipment's weight bracket.

For example, the service UPS SurePost’s weight brackets go up in 1lb increments. A shipment using UPS SurePost with a weight of 3.2lbs and uses actual weight as the calculation method, the chargeable weight will be 4lbs

Why Do Couriers Use Volumetric Weight?

Many couriers consider both volumetric and actual weight to calculate shipping costs because it better represents the true cost of delivering your package. The larger the parcel is, the more room it takes up on a vehicle or aircraft, therefore, the more it costs to transport. If an item is large but light, the price will be based on the size rather than the weight.

Do All Couriers Use Volumetric Weight?

Not all - some postal couriers only consider the shipment's actual weight when charging you. However, they have other restrictions, like maximum parcel size. If you exceed these, the couriers may not accept your parcel, or they might upgrade the service and adjust the price accordingly. 

Why Is It Important to Provide Accurate Weight and Dimensions?

The courier will almost always measure the dimensions and weight of each parcel during transit. This is an automatic process, using very accurate laser measurements.

If there is a difference between what they measure and what you declared on Easyship, you may be charged extra according to the changes in shipping costs. If the parcel is bigger/heavier than declared, you will be charged to make up for the difference. This works the other way too; if the parcel is smaller/lighter than declared, you will receive an appropriate partial refund.

Weighing and measuring your parcel as accurately as possible is the best way to limit shipping charge adjustments.

Advanced Explanation

Chargeable weight, like actual weight, is measured in kilograms or pounds. It is the value used to calculate shipping rates for a given courier service. Chargeable weight is different from actual weight when the courier services account for the length, width, and height of the parcel, in addition to its weight.

The density of a parcel is what determines how chargeable weight is calculated. High-density parcels are relatively heavy and small. For these, the actual weight is used as chargeable weight—no change. Low-density parcels are relatively light and bulky. These are rounded up to a minimum chargeable weight for the box’s size. This minimum value is sometimes called dimensional weight or volumetric weight.

The line between high-density and low-density varies by courier service. SF Express domestic shipments, for example, use a threshold of 200 kg/m³. Any box less dense than that will be rounded up to a minimum chargeable weight for its size. In general, international courier services set the bar a bit higher, so parcels are more likely to be rounded up to a minimum value.

Minimum chargeable weight = (height x width x length) x threshold density

Note: Couriers actually describe the dividing line between high-density and low-density parcels in different terms. For a given service, they may define a dimensional factor used to calculate a parcel’s minimum chargeable weight (aka volumetric weight). This factor is equal to one divided by the value that separates high-density from low density.

DIM factor = 1200 kg/m³ = 5,000 cm³/kg

Typical Density Thresholds

An Example

Imagine you want to send a care package to your cousin, who just started university in Dublin. You have one box of books and one box of pillows. You’ve selected USPS Priority Mail Express, which only applies minimum chargeable weights to parcels larger than one cubic foot.

 

The box of books is below the volume threshold, so it will be charged according to its actual weight. Even if the courier service set no volume threshold, the box is also above the density threshold- it would still be charged according to its actual weight.

CWbooks = AWbooks

The box of pillows is both above the volume threshold and below the density threshold, so the minimum chargeable weight applies. We calculate this value by multiplying the box volume by the density threshold.

CWpillows = 4 ft³ 12.5 lbft³ = 50 lb >AWpillows

You can think of the same calculation in terms of volumetric weight and DIM factor.

DWpillows = 4 ft³ 139 in³lb = 50 lb >AWpillows

Sometimes, a picture is worth a thousand words. If you plot actual weight vs. volume, the division between high-density and low-density (i.e. the DIM factor) is a straight line. Any parcel above the red volume threshold and left of the blue density threshold will have its chargeable weight calculated according to the formula above. This formula is equivalent to tracing a horizontal line from the dot representing the box of pillows all the way right to the density threshold.