Try Our Dimensional Weight Calculator

Calculating Dimensional Weight

Dimensional weight since Amazon is basing the FBA fee off of item weight or dimensional weight whichever is greater – dimensional weight is easy to calculate but people just make it way too confusing – it’s simply:

L x W x H = X


Divide X by 139 to get Y


Round to the next whole LB (lot of ppl miss this part) – this is the weight that is used to calculate the FBA fee if using dimensional weight.

So How Do We Use This Info?

You work backwards to figure out if you can reduce your FBA fee by shrinking your dimensions slightly.

For example: If you have a product that weighs 2-3lbs but has the dimensions 16 x 9 x 3, your dimensional weight is 3.11 lbs (16*9*3 = 432 / 139 = 3.11) and because of that .11 lbs of extra dimensional weight, you’re bumped up to 4 lbs and the next pricing tier from $5.79 to $6.43 or $.64 more per unit or an 11% increase in fees.

So what do you do? You have to determine whether it’s reasonable that you can shrink your dimensional weight to 3 lbs or less by slightly reducing your dimensions L x W x H to equal less than 417 (which is just 139 * 3).

If you can shave just 1 or 2 inches off like 15.9*8.9* 2.8 = 396 / 139 = 2.85 lbs = bumped up to 3 lbs not 4 – note dimensional weight is a factor in calculating your storage fees too.

A group of people working on a laptop with a calculator while engaging in marketing management activities.

NOTE: 18 x 14 x 8 is the Standard Size and if you exceed these dimensions, you’re going to go into Small Oversized where the math is slightly different.

Sometimes people want to know when they sent in a particular SKU last, how many units were shipped in, etc. But they think the only way is to go through the FBA shipments and find the last shipment for that SKU.

It’s Much Easier and Faster Doing This:

Reports > Fulfillment > Under Inventory > Received Inventory > simply enter SKU and filter to date range wanted. It will identify all of the FBA shipments into the FC for that particular SKU