Choosing size is the biggest concern when you’re renting a storage unit. You don’t want a unit that’s too small, but you also don’t want to waste money on one that’s too big. How do you figure out which size is right for you?! 

If you’re interested in any of our storage units across our facilities, we offer a free storage space calculator that estimates what size makes the most sense for you. It’s easy to use, though we appreciate you might want to make more accurate calculations. 

That’s why we made this guide! It will walk you through the steps required to calculate how much storage space you need in a unit. We’ll also talk about your specific storage needs to help you come to the right conclusion. By the end, this guide will assist you in picking out the ideal storage unit in the perfect size – and for the best price! 

How To Calculate Your Storage Space Needs

Storage units are usually split into three size-based categories: 


  • Small Units – They can be anywhere from 1m² to 9m²  
  • Medium Units – Typically around 10.8m² up to 13.5m² 
  • Large Units – Anywhere from 18m² upwards

There’s a key thing to note here; storage units are given in metres squared, rather than the volume of the unit. Essentially, this tells you the amount of floor space you’ll have to store your items. 

Keeping that in mind, calculating your storage space needs is as simple as seeing how much floor space you require. The best idea is to put your items in boxes and then organise them in a space. Get some measuring tape out and work out the total area covered in m². For example, if you have a collection of boxes that takes up 12m², you know that a medium unit is likely enough for you. 

Moreover, consider any special items you wish to store. If you’re trying to store a car in a unit, you’ll need one that’s big enough to do this. A large 18m² unit is enough for most cars while a 27m² one is ideal for campers. 

We also think it’s worth thinking about the vertical storage space. You can stack boxes on top of one another to take advantage of the extra space above your items or you can install shelving racks to keep smaller things in the room too.

Keep Your Storage Usage In Mind

The calculation above will help you work out a rough estimate of how much floor space you require. Before you jump to conclusions, think about the intended storage usage. Specifically, how long do you wish to keep your storage unit? 

If you only need it in the short term, then it’s more cost-effective to purchase as small a unit as possible depending on your needs. It doesn’t matter if things are crammed in there as it’s a temporary solution while you move house or deal with renovations. 

However, if you have long-term storage needs, we recommend sizing up. If your calculations show that 15m² will be more than enough, it’s better to opt for the next size up. Why? Because your storage space needs may grow over time. This is especially true if you need business storage. You might begin with the need for a small unit, but within a year you gradually store more items and discover that a large unit makes more sense. Going for a large one from the beginning saves you from transferring your items from one unit to another. 

Think About Any Special Requirements

Not all storage units are made the same. Some come with special features, such as climate control or improved accessibility for vehicles. As a result, the size of the unit you need may depend on your special requirements. 

As an example, what if you need to store items at a controlled temperature? Small units might not have climate-control functionality, so you’d need to rent the smallest possible unit with this feature. The same goes for units that can be accessed by cars or vans – if this is a necessity for you, then you have to pick a size that a) gives you the space you need and b) lets you drive right up to it for loading/unloading. 

It’s Better To Have Too Much Space Than Not Enough

If you’re ever debating between two storage unit sizes, the best approach is to opt for the larger one. As mentioned before, it gives you room to store more items if required. Additionally, it’s better to pay for a bit more space than not having enough. At the very least, it gives you more room to store items that you don’t use at home – which could free up space in your garage or around the house!