Start by measuring what you actually own

The most reliable way to pick a storage unit size is to measure the items you plan to store, not guess at how much space they will take. Most people underestimate volume by 30 to 40 percent because they do not account for the air around objects or the way boxes stack unevenly.

Go through your home room by room and write down what is leaving: furniture dimensions (length, width, height), the number of boxes, appliances, sports equipment, or anything else. If you have a couch that is 84 inches long, 36 inches deep, and 32 inches tall, write those numbers down. If you have 50 moving boxes, measure one box and multiply. This takes an hour but saves you from renting a unit that is too small or paying for space you do not use.

Once you have a list, add 20 percent to your total volume as a buffer. Storage units are rarely packed wall-to-wall; you need room to walk, to access items in the back, and to shift things around without damage.

Key Takeaways

  • Measure your actual items rather than guessing, because most people underestimate how much space they need by 30 to 40 percent.
  • Common sizes are 5x5 (25 square feet, holds a studio apartment), 10x10 (100 square feet, holds a one-bedroom), and 10x20 (200 square feet, holds a two-bedroom or small house).
  • Add 20 percent to your calculated volume to account for walking space and the way items actually stack in a real unit.
  • Visit the facility and walk inside a unit the size you are considering, because square footage alone does not show you ceiling height or how shelves and aisles affect usable space.

Standard storage unit sizes and what they hold

Storage facilities offer units in standard sizes, and knowing what each one typically holds helps you narrow down your choice. A 5x5 unit (25 square feet) holds the contents of a studio apartment or a small bedroom — roughly 50 to 75 moving boxes, a bed frame, a dresser, and a few chairs. It is the smallest option most facilities offer and works for seasonal items, holiday decorations, or overflow from a small space.

A 10x10 unit (100 square feet) is the most common size rented. It holds the contents of a one-bedroom apartment — typically 100 to 150 boxes, a bed, a couch, a dining table with chairs, a dresser, and several shelves. If you are storing furniture from one bedroom plus a living room, this is usually your size.

A 10x20 unit (200 square feet) holds a two-bedroom apartment or the contents of a small house — roughly 200 to 300 boxes, multiple bedroom sets, a full living room, a kitchen table, and appliances. Many people use this size when downsizing a house or storing items during a renovation.

Larger sizes like 10x30 (300 square feet) and 20x20 (400 square feet) exist but are less common. Before you assume you need a bigger unit, visit the facility and walk inside one the size you are considering. Ceiling height, the placement of support beams, and the width of the door all affect how much you can actually fit.

Account for how you will arrange items inside

The way you pack a unit changes how much fits. If you stack boxes floor to ceiling in neat rows, you use space efficiently. If you leave furniture in the middle of the floor with boxes around it, you waste 20 to 30 percent of your space. Before you commit to a size, think about your packing strategy.

Furniture should go against the walls. Boxes stack on top of each other, but only up to about 5 feet high if you want to reach the top safely and without crushing the bottom boxes. Appliances like refrigerators and washing machines take up floor space but do not stack, so they eat into your usable area. If you have several large appliances, you may need a bigger unit than your box count alone suggests.

Shelving units, which you can bring in yourself, multiply your usable space. A 4-shelf unit that is 36 inches wide and 18 inches deep takes up 6.5 square feet of floor space but holds the equivalent of 15 to 20 boxes per shelf. If you plan to use shelves, you can often fit everything in a smaller unit.

Consider climate control if you are storing sensitive items

Climate-controlled units cost more — usually 30 to 50 percent more per month — but they maintain a steady temperature and humidity year-round. You need climate control if you are storing wood furniture (which warps in heat and humidity), electronics, photographs, documents, artwork, or anything that degrades in extreme temperatures.

Standard (non-climate-controlled) units work fine for metal items, plastic storage bins, tools, and seasonal decorations. However, if you live in a region with very hot summers or very cold winters, even standard items can suffer. A leather jacket or a wooden dresser left in a 120-degree unit for three months can be permanently damaged.

Climate-controlled units are also smaller in total capacity because the cooling system takes up space. A climate-controlled 10x10 may feel slightly smaller than a standard 10x10, so account for that when you measure.

Visit the facility before you rent

Never rent a unit based on the website or a phone call. Visit the facility, walk inside an empty unit the size you are considering, and bring your measurements with you. Stand in the middle and imagine your furniture arranged. Open and close the door to make sure it swings the way you need. Check the ceiling height — some facilities have low ceilings that prevent you from stacking boxes as high as you planned.

Ask the staff about the access hours. Some facilities are open 24/7; others close at 6 p.m. or on weekends. If you need to retrieve something on a Sunday, a facility that closes at 5 p.m. on weekends will not work for you. Also ask whether the unit has a door that locks from the inside (so you can lock it while you are inside) or only from the outside.

Check the lighting inside the unit and in the hallways. Poor lighting makes it harder to find things and increases the risk of damage when you are moving items in or out. A facility with motion-sensor lights or bright overhead fixtures is easier to work in than one lit only by a small window.

Account for future growth or downsizing

If you are storing items temporarily — during a move, a renovation, or a separation — think about whether your needs will change. If you are moving into a smaller apartment and storing furniture you might sell later, you may need less space in six months. Renting a slightly smaller unit now and upgrading later is often cheaper than paying for unused space.

If you are storing a business inventory or items you plan to add to over time, rent a unit slightly larger than your current needs. Moving everything to a bigger unit mid-contract is disruptive and costs money. A 10x15 instead of a 10x10 gives you room to grow without the expense of relocating.

Compare prices and contract terms across facilities

Storage unit prices vary widely by location, season, and facility. A 10x10 unit in a rural area might cost $60 per month, while the same unit in a city costs $150 or more. Call at least three facilities in your area and ask for their current rate for the size you need. Ask whether the first month is discounted, whether there is a deposit, and whether the price is locked in or can increase.

Some facilities offer a first month free or 50 percent off if you sign a six-month or one-year contract. Others raise the price after the first month. Read the contract carefully and understand what you are paying for. The cheapest facility is not always the best deal if it has poor security, limited access hours, or a location that is inconvenient for you.

Frequently Asked Questions

What size unit do I need for a one-car garage worth of stuff?

A one-car garage is roughly 150 to 200 square feet. A 10x10 unit (100 square feet) holds about half that volume, so you would likely need a 10x15 or 10x20 depending on what is in the garage. Measure your actual items first — a garage full of lightweight boxes takes less space than one with heavy tools and equipment.

Can I fit a car in a storage unit?

A standard car is about 15 feet long and 6 feet wide. A 10x20 unit is 10 feet wide, so a car does not fit. You would need a 20x20 or larger, and even then the car takes up most of the space. Most facilities have separate outdoor parking for vehicles, which is cheaper than an indoor unit.

What happens if I rent a unit that is too small?

You will either have to leave items behind, rent a second unit, or upgrade to a larger one mid-contract. Upgrading usually costs more because you lose the discount on your original contract and pay a higher rate for the new unit. Measure carefully the first time to avoid this.

Is a 5x5 unit big enough for a bedroom set?

A bedroom set (bed frame, mattress, dresser, nightstand) fits in a 5x5, but there is little room for anything else. If you also have boxes, a desk, or other furniture, you need at least a 10x10. A 5x5 works best for seasonal items or a single room's worth of boxes, not mixed furniture and boxes.

Do I need to buy insurance for my storage unit?

The facility's insurance covers the building, not your items. You need renter's insurance or a storage-specific policy to cover theft or damage. Ask your renter's insurance provider whether your policy extends to storage units, or ask the facility for a list of insurers they work with.