How Can You Calculate Pallet Rack Load Capacity?

9 November 2019

Too often it happens that supply managers underestimate the capacity they need when ordering a racking system, which, in turn, leads to overstocking. Knowing the pallet rack load capacity of your warehouse is necessary because of two substantial reasons:

  1. It will help you create and maintain a safe working environment.

  2. It will enable you to make the best inventory decisions every single step of the way.

There is nothing to guarantee that your employees will notice when a rack is overloaded, which is why a great deal of work place accidents take place. Your primary aim is to avoid the latter.

Specified Capacities and Assumptions

Most rack manufacturers will usually deliver a rack capacity table with their product. For the United States, these have to abide by the RMI/ANSI 16.1-2012. Under no circumstance should you purchase a racking framework from a company that cannot give you precise capacity information for each of the loading bays, as well as for the beams, based on the width and the spacing between the latter.

What’s more, these capacities assume certain usage conditions that have to be fulfilled. If either or more of them are not true, then the information in the table is more or less useless. Let’s briefly go over these hypotheses:

  • The industry standard is non-seismic use. You have to ask manufacturers directly for racks that are earthquake safe.

  • The numbers are almost always based on interior usage. If you intend to expose your racks to outside conditions, their integrity might be affected over time.

  • The capacity from one type of storage does not apply to another – if you get a selective racking catalogue, it’s for that kind of rack framework and nothing else.

  • The capacity is only true for installation in strictly upright condition.

  • The number also includes the weight of the rack, decks, frames, and any other accessories.

Calculating Pallet Rack Load or Upright Capacity

If you’re looking to find out what type of racking framework you should order, then you need to start your computation from your heaviest pallet weight. You take that number and multiply it by the number of pallet positions per level to find out the beam capacity or the maximum shelf load. If you intend to store just one, then no multiplication is necessary. For two, double it and so on.

For a pallet that is 1200 kg (2645 lbs.), your total rated capacity for each bay must be at least 2400 kg (5290 lbs.) if you want to store two pallets on each level. Alternatively, if your rack system’s total rated capacity for each bay is, for example, 4000 lbs., then your maximum unit load cannot exceed that number divided by the amount of pallets you intend to put on each shelf.

The maximum unit load is your heaviest loaded pallet. Usually, the greater upright capacity of your beams and the less space between racks, the more capacity you benefit from. If you want to know your upright capacity, then all you have to do is calculate how many levels you can afford to install within your clear height.

The latter is the compliant vertical distance you can use for storage purposes – your building might be 37 feet tall, but your clear height might just be 32 feet. Then, you have to calculate pallet frame capacity. For instance, if you assume 50 inches of space between one rack and the one above it, as well as 5 inches of thickness for the latter, your frame capacity is 60 inches.

In other words, if you have 32 feet of height to work with and you leave at least 80 inches for floor storage under the first level, then you can go 5 pallets high (6, if we’re also counting the ground ones).

Capacity Does Not Equal Density

Despite the greater capacity of certain rack systems, their superior numbers do not necessarily provide you with more density per square foot. If your warehouse layout is not suited to your operations, your inventory, or its turnover, you’ll lose value due to improper management of your density. You can also lose value by acquiring a capacity that far exceeds what you can hold in peak season.

Ideally, you want to discuss your needs with your manufacturer from the get-go, rather than place an order without giving it a second thought. Most companies that build these frameworks are experienced and well-suited to give you advice on a system that would work best for you.