A lot of warehouse managers see gravity flow racks and consider them just a means to an end – an easy way to move product back and forth through a warehouse while helping speed up delivery and picking times.

What they don’t expect, however, is that these racks can actually have a big impact on the way they store items, the way they pick items, and how their warehouse operates overall. Using gravity flow racks to store items is referred to as flow storage, while any other warehouse storage method where the items remain stationary on shelves is referred to as static storage as the products themselves are rarely if ever in motion after they’re received.

Neither of these approaches is inherently better than the other, it all depends on what you need to store and what your facility would accommodate. Let’s ask a few questions about what your warehouse does and how you can benefit from each approach:

How do you pick your items?

You can ask a million warehouse managers this question and get a million different answers, but there’s a few key terms it really boils down to. Each picks are a commonly used form of item picking that focuses on one item per picking job and/or carton, allowing you to more easily focus on the order at hand as well as the item in question. Carton flow can help with each picks by helping to naturally reinforce organization and proper product order by maintaining first-in-first-out (FIFO) picking and supports increased product density.

Otherwise, if you use case picks, you may be better off with static storage like pallet racks as they allow easier access to entire cases and don’t rely as much on FIFO planning.

How often do items need to be moved?

Speaking of FIFO, this can actually have a huge impact on which storage option you need. Do you deal in products that need to be moved by a specific date? You’re probably thinking food storage, and while this is a great option for making sure everything goes out by its expiration date, there’s plenty of benefits to using FIFO. Do you carry products with a hard-and-fast street date like video games, movies, or other consumer electronics? Or what about pharmaceuticals that need to be rotated for safety? Flow storage can help with faster-moving items that need to be handled with FIFO, whereas static storage is better for slower-moving items or items that aren’t as time sensitive, as they won’t be competing with other shelves for space as badly.

How many picks do you encounter per day, as opposed to items?

This is a metric that goes surprisingly misunderstood in many warehouses, but understanding how many individual picks an item gets as opposed to how many physical items you have of each SKU can help influence what goes where. If a product produces a large number of picks, it’s a good candidate to move onto flow storage as the speed and ease of access will help increase productivity. That said, it isn’t a be-all-end-all solution; flow storage takes up a lot more space and is much more costly, so it’s best saved for the faster-moving products that need the speed increase.

How much room do you have?

Finally, even if you have some products that could benefit from flow storage, you really need to figure out how much space you have and if this is a practical option. Don’t let your desire for flow storage take away from storage you need for other products or operations, and if you have limited space it might cause more problems than it solves, no matter how excited you are to see those crates rolling down the line.