As the provider of secure storage services in Chicago, many clients ask us, "How big of a storage unit do I need?"

We get it - selecting from the many storage companies out there can be daunting, not to mention measuring your things and trying to visualize how they’ll fit into a storage unit.

To make it easier, we have compiled a useful storage unit size guide and provided some useful cost-saving advice so you make an educated decision on which unit is most suitable for your requirements.

5 Steps to Choosing the Perfect Storage Unit

With the right information and resources, you’ll be able to find a safe and secure storage unit that meets your budget and storage needs.

#1. Determine the Storage Unit’s Function

how to choose a storage unit

Determine what items you plan to store first. It would be impractical to rent a mini storage unit for a queen-size mattress or an average-size unit for a few boxes. If you need to store an entire household of items, you may need to rent multiple storage units.

A large unit could be suitable for a garage filled with things that need to be cleared out. Small storage units can also store seasonal items or a college student's belongings, or if you are merging two households or cleaning out an inherited house.

Once you know how many items need storage and their size, you can decide on the correct storage unit.

#2. Create an Inventory of Your Belongings

Before estimating the average storage unit size you need, it's important to take inventory.

Start by listing all the items you want to store, including furniture, electronics, appliances, books, artwork, clothing, and other items. Make sure to note the condition of each item on your list, such as if it's in good condition, average condition, or poor condition. This will help you determine the best storage solutions.

For instance, if you're looking to store the contents of a small study, your inventory may include things like a desk, chair, filing cabinet, boxes, shelves, office equipment, and so on.

#3. Double-Check Your Storage Options

Ensure you have used all the available storage space in your home.

It's worth taking five minutes to see if there are partly empty closets or unused corners of your garage or home to store smaller items. For example, many people forget about the cupboard located above the refrigerator or don’t make use of the empty space under their beds. Doing so could save thousands of dollars a year in storage costs.

#4. Calculate How Much Space You Need

To estimate the space you need for storing boxes, consider the dimensions of your largest and bulkiest items and the approximate number of boxes.

You can calculate the required space in two different ways:

1. To find your items' total square foot measurements when stacked together, multiply the length and width of the things or add each item's measurements individually.

  • For example, if the pile comes out to 8 feet by 8 feet, you will need a storage unit of at least 64 square feet.

2. To calculate the total cubic footage of your items, you can either multiply their length, width, and height when stacked together or add each item's measurements individually.

  • For example, if the pile is eight by eight by 8 feet, you would need a storage unit of at least 512 cubic feet.

Generally, a small storage unit has an area of 50 square feet (400 cubic feet), a medium storage unit has an area of 150 square feet (1,200 cubic feet), and a large storage unit has an area of 300 square feet (2,400 cubic feet). To give a basic estimate, a small unit should fit the contents of a single bedroom, while a large storage unit can hold up to five bedrooms' worth of items.

#5 If You’re Unsure, Opt for One Size Bigger

how to pick a storage unit

Having a storage unit that is too small for all your belongings can be dangerous!

Boxes should be stacked at most four high, and furniture should be stacked at most two pieces tall to avoid accidents when unpacking. It can also be difficult to access items in a too-small storage unit, increasing the chance of injury.

Additionally, a larger storage unit space might be worth considering, even if only a few more dollars a month. Sometimes, a bigger unit might be cheaper due to more availability, or you might be able to pay a lower rate for a non-climate-controlled rental. However, you should only do so if your items aren’t climate sensitive.

Standard Storage Unit Sizes

Below are storage space sizes (most storage units are typically eight feet high) with descriptions of items that can be stored in them and their common uses.

Sizes Common Dimensions (feet) Square Footage Cubic Footage What fits
Small 5x5 - 5x10 25-50 200-400 Up to one room
Medium 5x15 - 10x15 75-150 600-1,200 Up to three rooms
Large 10x20 - 10x30 200-300 1,600 - 2,400 Up to five rooms

Small Storage Units

  • 5’x5’ Units: A 5x5 storage unit is the smallest storage unit size - as "big" as a small coat closet. It is a great option for storing items you don't use often, such as seasonal clothing, bicycles, and small pieces of furniture.
  • 5’x10’ Units: These units are approximately the size of a small walk-in closet. They can comfortably store small pieces of furniture, such as sofas, chairs, chests of drawers, and even a full or queen-sized box spring and mattress. Businesses will find these units a great option for storing company supplies and records.

Medium Storage Units

  • 5’x15’ Units: This type of storage is 25 square feet and is perfect for storing seasonal items or other items you don’t need to access frequently. Although it’s not recommended for larger furniture items, a five-by-five unit can hold a dresser or a twin-size mattress set, making it great for students who need short-term storage space.
  • 10’x10’ Units: This is the most popular standard storage unit size. 10’x10’ are about half the size of a standard one-car garage and offer 100 square feet of storage space. This is enough space to store the furnishings of a one-bedroom apartment, including appliances, furniture, and a dozen boxes and supplies. They can even fit the entire contents of a large family room.
  • 10’x15’ Units: If you need to store the contents of a small house, a large two-bedroom apartment, or even just 3 office spaces, a 10x15 storage unit is the ideal choice. Its 150 square feet of space is slightly larger than a 10x10, making it perfect for storing larger items such as furniture and appliances.

Large Storage Units

  • 10’x20’ Units: Looking for a way to keep your home uncluttered and store a lot of bulky items? A 10'x20' can store couches, wardrobes, double beds, kitchen appliances, and many boxes, making it ideal for moving families or even those staying put. Additionally, this size unit is large enough to store a car.
  • 10’x30’ Units: If you need to store a vehicle, whether a vintage car, campervan, pickup truck, or even a small boat, you should consider renting a 10'x30' space. This size is great for families who are moving, remodeling their homes, or leaving the country for an extended period of time. Businesses can also use the space to store tools, bulky equipment, and merchandise.

Extra-Large Units

how big of a storage unit do i need

What is the biggest storage unit? The biggest storage unit exceeds 300 square feet. These are most commonly used by businesses and organizations to store items such as inventory, materials, and equipment for extended periods of time. In certain circumstances, the largest storage unit size may also be used to store boats, trailers, and other vehicles, though, as we mentioned, a 10x30 unit will suffice.

Money-Saving Strategies for Storage Unit Rental

Accurately estimating the storage unit size you need saves time and money. Here are some more cost-effective tips for finding the best storage unit:

Compare the Costs

Storage units often cost more than your stuff. For example, if you rent a unit to store a dresser, queen bed, and a few bookshelves, it will probably cost about $150 per month—or nearly $1,800 per year. Unless sentimental or of high value, it’s sometimes cheaper to rebuy everything later.

Identify Your Biggest Items

If you don't have the time to make a thorough list of what you need to store, you can quickly determine the right storage unit size by measuring your longest and widest items. According to our storage unit size guide, anything bigger than 15 square feet usually requires a large unit.

Visit a Storage Facility

Check out the units in person to better understand how big they are and how many boxes you can fit in them. You can also see how secure their property is and what their surveillance is like. Visiting a facility and scoping it out can save you hundreds of dollars.

Inquire About the Size

Don't just rely on the sizes published on storage unit companies' websites. Instead, call nearby facilities and give them your estimated square or cubic footage. They may have more sizes available than what's listed online,

Talk to Several Companies

Talking to multiple storage unit companies may benefit you by allowing comparison of prices, services, and amenities; helping you choose a facility that fits your needs and budget; enabling you to negotiate better rates and terms; and giving you a better feel for customer service and atmosphere.

Consider Moving Containers

what storage size do i need

Moving containers are a great, budget-friendly choice and can be stored at your home for a small monthly fee. Their flexibility makes them an ideal choice for people on the go, or those who need a short-term storage solution.

You can rent for as long as you need, and you can even have the container picked up and moved to another location if necessary. This could potentially help you save money, as well as eliminate the hassle of having to transport your items to and from the storage facility.

Rules of Thumb

Approximately 10% of a living space corresponds to the required storage space.

In general:

  • A one-bedroom or studio apartment = five-foot by 10-foot or five-foot by 15-foot unit.
  • A two-bedroom apartment = 10-foot by 10-foot or 10-foot 15-foot unit.
  • A two-bedroom house = a 10-foot by 20-foot unit.
  • A three-bedroom house = 10-foot by 25-foot unit.
  • A four-bedroom house = 10-foot by 30-foot unit.
  • A standard car = at least a 10-foot by 20-foot uni.
  • A motorcycle = at least a five-foot by 10-foot unit.


Now that you know how to choose a storage unit, the next step is finding a trusted company to take care of your belongings. Alliance Moving & Storage provides residential and commercial customers with secure and reliable long-term and short-term climate-controlled storage units.

Our storage units are equipped with 24/7 video surveillance and situated in brightly lit areas, allowing you to access them during regular business hours. We are available to assist if you need a storage facility while changing locations.

Contact our Chicago storage company today!