One of the questions we get asked every day is: “what is the right size of storage unit I require?”.

The answer to this will be different for every customer. It will be dependent on what you are looking to store and the reason you need the storage. The way to get an estimate of the size required is to first assess what you are looking to store at your home or office. Once you have made a list of these items then you can start to understand the actual requirement. We have a helpful Storage Unit Size Guide to help you once you know how many boxes you will be storing.

The other important thing to consider is, will you need access to the items that are in store. If you do, then you require more space for circulation. There are many guides online which will help you understand and assess how much space you need.

Another important point to consider is that you are only paying for the floor plate sq. ft. wherein fact a storage room is a cubic area. Therefore, if you can stack your possessions then you can utilize the space much more efficiently.

The most accurate way to understand your space requirement is to visit the storage facility and look at the various sizes of rooms. This will give you a great idea and is by far the best way of getting to book the right size. However, if you do not have time, then the next best way is to check out various size estimator guides online.

One of the main benefits of self storage is the numerous sizes that are available, therefore you only rent as much space as you need for as long as you require.

Standard Storage Unit Sizes

Let’s go through the different standard sizes of self storage units and generally what you can fit in them.


At the smallest end, you can rent a locker. These are generally one cubic metre. Clearly, you cannot fit much in them however if you’re just looking to store a few archive boxes then they are ideal.

15 Sq Ft

The next size up would be a 15 sq. ft. unit. This is like a walk-in wardrobe. If you’re just looking to stack boxes then a room of this size can normally hold around about 50 small boxes. Generally, the units are somewhere in the order of 8 ft. high and will be 5 ft. wide and 3 ft. deep.

20 Sq Ft

The size after that would generally be a 20 sq. ft. unit. This would be able to hold around about 60 small boxes. In terms of its dimensions, it would be 5 ft. wide 4 ft. deep and generally 8 ft. high although this will vary depending on the individual storage facility.

25 Sq Ft

A 25 sq. ft. unit is the same size as a standard garden shed. This would hold around about 75 small boxes and in terms of its dimensions would be 5 ft. wide by 5 ft. deep and generally again 8 ft. high although this may vary.

35 Sq Ft

A 35 sq. ft. unit would be capable of taking the contents of a small studio flat or a very small one-bedroom apartment. Generally, the dimensions are 7 ft. wide by 5 ft. deep and 8 ft. high.

40 Sq Ft

A 40 sq. ft. unit is the size of a large garden shed. Again, this would take the contents of a one bedroom flat. The dimensions would be 8 ft. by 5 ft. by 8 ft. high.

50 Sq Ft

One of the more popular sizes is 50 sq. ft. This is generally the size of a transit van and would hold the contents of a one bedroom flat. These units are generally 10 ft. with a depth being 5 ft. Therefore, it can accommodate beds, wardrobes and larger pieces of furniture.

75 Sq Ft

A 75 sq. ft. unit is the size of a Luton van. This will roughly take the contents of a two-bedroom flat or house. Its dimensions are generally 7.5 ft. wide by 10 ft. deep and again 8 ft. high.

100 SqFt

A 100 sq. ft. room is a similar size to a single garage and can take the contents of a 2-bedroom home. The dimensions are 10 ft. wide by 10 ft. deep and generally 8 ft. high

125 SqFt

A 125 sq. ft. room will hold the contents of a 3-bed home. The dimensions are generally 12.5 ft. wide 10 ft. deep and 8 ft. high.

150 SqFt

A 150 sq. ft. room will hold the contents of a 7.5-tonne lorry. These units are 15 ft. wide 10 ft. deep and 8 ft. high.

175 SqFt

A 175 sq. ft. unit will hold the contents of a 4-bedroom house. These units are 12 ft. wide by 15 ft. deep and 8 ft. high

200 SqFt

A 200 sq. ft. room is the size of a double garage and will hold the contents of a 4-bedroom house. The dimensions are generally 20 ft. wide by 10 ft. deep and 8 ft. high

250 SqFt

A 250 sq. ft. room will hold the contents of a 30-ft. articulated lorry. These units are generally 12.5 ft. wide 20 ft. long and 8 ft. high.

There are numerous other sizes that self storage facilities provide. Generally, this is dictated by the type of building and its configuration. Therefore, in some cases, you may find some odd sizes or even rooms with structural columns running through them. These are great if you’re looking for cheap storage because often they are discounted.

Room Location

Many self storage facilities in the UK are conversions of old buildings, for example, warehouses and factories. Therefore, another consideration you need to think about is the location of the room within the building. If you need regular access to your unit then you will want to be located close to the door. But if you are just putting your goods into storage and you will not actually access the facility until they are removed, then you do not need to have the convenience of being close to the entrance. You could store your goods in a unit which is some distance away from the door. The benefit is, it is often cheaper to do this.

Therefore, when you are inquiring about your storage unit, ask the staff whether they have a different price for the same size storage room subject to where they are located within the building.

Also, if you are shown a unit that has some kind of obstruction, such as a structural column or anything else which reduces the actual usable space, for example, the height of the unit is restricted, then always ask for a discount. These units are harder to rent, and the company would be keen to have these rented and will probably be negotiable on price.

Drive Up Storage Units

Some storage facilities also offer outside storage. This may be in a shipping container or a purpose-built external drive up self storage unit. With shipping containers, there are generally two standard sizes. These are 20 ft. long by 8 ft. wide and 8 ft. high, equating to 160 sq. ft.

The largest shipping container is 40 ft. long, 8 ft. wide and 8 ft. high. This is 320 sq ft. Although shipping containers and drive up storage units are very convenient to load and unload, you should think about whether they are ventilated and insulated.

A shipping container when built would not have any ventilation. Therefore vents have to be installed into the sides or back of the unit when it is converted into a storage unit.

The other important consideration is that the ceiling should be insulated. If the ceiling is not insulated then there is often a problem with condensation, particularly in the colder months.  This will produce moisture within the unit and create issues with your goods getting damp and becoming moldy.

Also, if you are taking an outside unit, be careful to look for signs of leaks and damp. You will be able to see evidence of this with watermarks on the ceiling or floor of the unit. If these are evident, asked the staff whether there has been a problem and has it been resolved.

Other Considerations

Don’t forget when you are renting a self storage unit it is not just the sq. ft. on the ground, you’re renting the height of the unit. Many facilities have been converted from old buildings and the ceiling heights can be very high. Standard heights are around about 8 ft.

Also, in a self storage facility, the doors should always open outwards. If they open inwards then you will be paying for space which you cannot use, because you need to be able to open the door. Most self storage facilities will have doors that open out, however, in old buildings where they have just turned old offices into self storage rooms, the doors may well open inwards.

Also, when looking at the size of a storage unit look at the type of door the unit has. There are two types of door in self storage facilities, one being a swing door and the other a roller shutter door. Just think about what you’re actually storing and whether it will go through the door and how convenient this is. For example, if you have large furniture it may be necessary to have a wider door aperture. Therefore you will require a unit with double swing doors or possibly a large roller door.

Another consideration if your storage is inside a building, is the access, i.e. do you need to take your goods in an elevator or around several corners to get to your unit. Both these things cause inconvenience when moving in and out.

Also, look at the trucks and trolleys that are available to customers to help them move. These are generally supplied by the company. However, it is worth noting how many there are because if you were, for example, moving in on a Saturday, this is a busy time and there will be a high demand for these pieces of equipment from other customers.

Also, look at the age of them, i.e. are they falling to pieces. This again will have implications on the smoothness of your move into the facility and should be part of the decision you make on where to store.

The answer to the question, “What Is the Right Size of Storage Unit For You?” will be determined by doing some homework. But this is time well spent and will pay dividends on move-in day.