Does shipping cost by size or weight?

The Truth About Shipping Costs: Size vs. Weight (and Why It Matters to You)

Ever wondered why that lightweight but bulky box of pillows cost you more to ship than a much heavier package of books? The world of shipping can seem like a black box of confusing charges, but the underlying principles are fairly straightforward: shipping costs are determined by either the actual weight of the package OR its dimensional weight (DIM), whichever is greater.

While this might seem like a small detail, understanding the difference between these two calculations can save you a significant amount of money on shipping, especially if you frequently send packages that are large but not very heavy.

Let’s break it down:

1. Actual Weight: The Simple Part

This is exactly what it sounds like. You put your package on a scale, and that’s the weight. Most shipping companies will charge based on this weight, rounded up to the nearest pound or kilogram. This is generally the determining factor for smaller, denser packages.

2. Dimensional Weight (DIM): When Size Matters More

This is where things get interesting. DIM is a calculation that factors in the size of your package. Shipping companies understand that large, even if lightweight, packages take up valuable space in trucks, planes, and warehouses. This space could be used for other packages that generate revenue. To compensate, they use dimensional weight.

How is DIM Calculated?

The specific formula for calculating DIM varies depending on the shipping carrier, but the general principle remains the same:

• Measure the length, width, and height of your package in inches (or centimeters).
• Multiply those dimensions together (Length x Width x Height).
• Divide the result by a “dimensional factor” or “DIM divisor” (a number set by the carrier).

The dimensional factor is the key. It essentially tells you how many cubic inches (or centimeters) equal one pound (or kilogram). Common DIM divisors range from 139 to 166 in the US, but always check with your chosen carrier for their specific number.

The Important Comparison: Actual vs. Dimensional Weight

Once you’ve calculated both the actual weight and the dimensional weight of your package, the shipping company will use the higher of the two to determine your shipping cost.

Why is DIM Important for You?

• Avoid Unexpected Fees: Understanding DIM allows you to estimate your shipping costs more accurately and avoid nasty surprises at the checkout.
• Optimize Your Packaging: If your package has a low actual weight but a high dimensional weight, consider downsizing the box or using more compact packaging materials. Even small changes in dimensions can have a significant impact on your shipping costs.
• Compare Carrier Options: Different carriers may have different DIM divisors. Shopping around and comparing prices can reveal significant savings, especially for larger packages.

In Conclusion: Size Does Matter in Shipping

While weight is undoubtedly a key factor in determining shipping costs, don’t underestimate the influence of size. By understanding the concept of dimensional weight and taking steps to optimize your packaging, you can save money and ensure a smoother shipping experience. Before you ship anything, take a few minutes to measure your package and compare its actual weight to its dimensional weight. Your wallet will thank you!