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Storage Unit Size Guide
How Big Is a 20x20 Storage Unit? Dimensions, What Fits, and Who It's For
Four hundred square feet, square. The dimensions of a real two-car garage, with what that means for vehicles, households and small businesses.
Compare Every Size
- 5x525 sq ft
- 5x1050 sq ft
- 5x1575 sq ft
- 10x10100 sq ft
- 10x15150 sq ft
- 10x20200 sq ft
- 15x20300 sq ft
- 10x30300 sq ft
- 20x20400 sq ft
- 10x40400 sq ft
- 15x30450 sq ft
- 20x25500 sq ft
- 20x40800 sq ft
Other Space Types
On This Page
- What a 20x20 Storage Unit Actually Is
- What Fits in a 20x20 Storage Unit
- What Does Not Fit in a 20x20 Storage Unit
- Who a 20x20 Storage Unit Is Right For
- How to Know If You Should Size Up or Down
- How to Pack a 20x20 Storage Unit Efficiently
- Climate-Controlled or Standard: Which 20x20 to Choose
- What a 20x20 Storage Unit Costs and How to Think About Value
- Frequently Asked Questions
- Reserve a 20x20 Storage Unit Near You
Section 01
What a 20x20 Storage Unit Actually Is
A 20x20 measures 20 feet on each side: 400 square feet of floor, a square 240 inches across. With 8-foot ceilings that gives you 3,200 cubic feet.
Those are close to the dimensions of an actual two-car garage, which is the most useful way to picture it. Most residential two-car garages run about 20 by 20 or 22 by 22 feet. If you can see your own garage, you can see this unit.
The square proportion is what makes it valuable. Every other large size we rent is longer than it is wide, which pushes you into a corridor layout whether you want one or not. A square floor lets you put things where they make sense.
The Floor, Drawn to Scale
Looking straight down, here is the floor at true proportion with one layer of 18-inch medium cartons across it. Thirteen fit in each direction, giving a hundred and sixty-nine per layer.
240 in / 20 ft wide · door on front wall
A hundred and sixty-nine medium boxes per layer. Five safe layers gives about 845 boxes, if the unit holds nothing else.
The Unit in Three Dimensions
Square footage undersells a unit this size, because what you are renting is volume. Both cutaways below show the same 20x20 at the same scale. The only difference between them is how the boxes are stacked.
Stacked five layers high
One layer on the floor
At this size the gap between those two drawings is enormous. Packing to head height rather than waist height is worth more square footage than most renters would ever pay for.
Section 02
What Fits in a 20x20 Storage Unit
Two Vehicles With Room to Use Them
A 15x20 fits two vehicles. A 20x20 fits two vehicles you can actually get into. At 240 inches of width, two at roughly 72 inches each leave eight feet to divide between the middle and the sides, which is full door clearance on both.
- Two full-size vehicles, including SUVs and standard-cab pickups within 20 feet of depth.
- A vehicle plus a boat on a trailer under about 18 feet overall.
- A classic car with room to work around all four sides, which nothing narrower allows.
- Six to eight motorcycles, ATVs or jet skis with access to each.
Check the Door, Not Just the Floor
Interior dimensions are only half the question. The roll-up door opening is narrower and lower than the unit itself, and at this size it is what actually decides whether a tall vehicle, a van with roof equipment or a trailer will go in. Confirm the door opening at the specific facility before booking anything close to the limits, particularly on height.
Storing a vehicle also carries requirements that storing goods does not: proof of current registration and proof of insurance. Motorised vehicles must be operable and free of leaking fluids. Towable trailers, including travel trailers, fifth wheels, pop-ups and utility trailers, do not need to be operable. Our vehicle storage page has the detail.
A Large Household, or Two Smaller Ones
Four hundred square feet takes a six to seven bedroom home outright, or the contents of two ordinary apartments stored separately down opposite walls with an aisle between. For families combining households, or storing for two relatives at once, the square floor makes that division practical rather than theoretical.
Shelving and Racking
A 20x20 has 80 linear feet of wall. Shelving along three walls gives 60 linear feet of run, and at five shelves high that is about 300 linear feet of shelf with a square working area in the middle. Sixteen to twenty pallet positions sit on the floor with room to move between them. Our business storage page covers commercial use.
Section 03
What Does Not Fit in a 20x20 Storage Unit
Beyond This Size
- Anything longer than 20 feet. The width is generous and the depth is not. Extended-bed pickups, motorhomes and larger boats are all out.
- Four vehicles. Two side by side is the practical limit; 20 feet of depth will not take two rows with access.
- Anything taller or wider than the door opening.
- A full business operation with forklift movement. A pallet jack turns here; a forklift does not.
Vehicles and Prohibited Items
- Vehicles without documentation. Proof of current registration and proof of insurance are required, and motorised vehicles must be operable with no leaking fluids.
- Flammable, combustible or hazardous materials: gasoline, propane, paint, solvents, fireworks, ammunition. This catches out contractors and equipment owners more than anyone, so drain fuel before storing.
- Perishable goods, or anything that attracts pests.
- Living things, including plants and animals.
- Anything illegal or stolen.
- Occupied or operational use. A storage unit is not premises. No working from inside it, no customers, no utilities.
Depth Is the Limit Here, Not Area
A 20x20 and a 10x40 are both 400 square feet. The 20x20 gives you width and caps you at 20 feet of length; the 10x40 gives you forty feet of length and caps you at ten feet of width.
If the thing you are storing is longer than twenty feet, no amount of square footage in this shape will help. Look at a 10x40, a 15x30, or a parking space sized by length.
Our full storage FAQs cover prohibited items in detail, and your rental agreement is the controlling document. At this size, where a unit may hold an entire inventory or a vehicle, read the agreement rather than relying on a general guide, including this one.
Section 04
Who a 20x20 Storage Unit Is Right For
Two-Vehicle Owners Who Want Access
The clearest case. Two vehicles with full door clearance on both, or one vehicle with working room all the way around it. For collectors and restorers this is the smallest size that behaves like a garage rather than a parking slot.
Households Combining or Downsizing
Two households merging, a parent moving in, or a large home going into storage while a build finishes. The square floor makes it practical to keep two sets of belongings separate and reachable.
Contractors Who Need to Work On Site
A work vehicle, racking on three walls, and a square floor with room to stage a job. Note that a unit is storage, not premises, so no operating from inside it, but staging and loading is exactly what the shape supports.
Businesses With Palletised Inventory
Sixteen to twenty floor positions, 300 linear feet of shelf, and a pallet jack that can turn. With month-to-month terms and 24/7 access, this replaces a small warehouse lease for a lot of growing operations.
Seasonal and Event Businesses
Landscapers, holiday lighting installers, caterers, event and rental companies. Equipment goes in during the off season and comes out in one trip, without paying for premises year round.
Section 05
How to Know If You Should Size Up or Down
Compare by Shape, Not Just Area
At this end of the range several sizes share square footage while behaving completely differently. A 20x20 is 400 square feet and so is a 10x40. One is a room, the other is a tunnel.
A 20x20 Is Right If Any of These Are True
- Two vehicles are going in and you need to open the doors
- You want to work around all four sides of something
- You are storing two households, or one very large one
- You need pallet positions and room to turn a pallet jack
- Nothing you own exceeds 20 feet in any direction
Choose Something Else If Any of These Are True
- Anything you are storing is longer than 20 feet, which wants a 15x30 or 10x40
- You need three or more vehicles, which wants a 20x40
- A 15x20 is meaningfully cheaper and tighter clearance is acceptable
- Your household is four bedrooms or fewer, which fits a 10x20 for considerably less
- You are storing one vehicle and nothing else, which wants a parking space
Check Two Units Against One
The price per square foot curve flattens at the top of the range, so a 20x20 is not always cheaper than two 10x20s at the same facility. It is worth ten minutes to price both. Two units also let you separate what you need from what you do not, which on a long rental can be worth more than the difference.
Our storage size calculator builds a recommendation from an item-by-item inventory.
Section 06
How to Pack a 20x20 Storage Unit Efficiently
A square floor is the easiest large unit to lay out and the easiest to waste, because there is no wall forcing you into a sensible arrangement.
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Plan the Layout Before Anything Arrives
At this size an unplanned load wastes more space than most people rent in total. Decide where vehicles, racking, heavy equipment and boxes go before the first item comes off the truck, and tell whoever is helping.
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Racking Beats Stacking, Decisively
Freestanding shelving or pallet racking along the walls turns floor area into usable volume and keeps everything individually reachable. Above about 300 square feet this is the single highest-return decision you will make.
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Keep a Full-Length Aisle, and a Turning Space
Run a clear path from the door to the back wall, and leave enough room near the door to turn with a hand truck or pallet jack. Losing roughly a third of the floor to access is the correct trade on a unit you will visit.
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Heaviest and Least Needed at the Back
Equipment, appliances and archive stock go furthest from the door. They are also the sturdiest platforms to stack against.
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Build Upward to About 80 Inches
Uniform cartons reach roughly 80 percent volume efficiency against 55 percent for mismatched sizes. On a unit this large that difference is measured in hundreds of cubic feet.
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Prepare Vehicles and Fuel-Powered Equipment First
Drain mowers, generators and power equipment, since fuel is not permitted inside. For a stored vehicle, clean it, inflate the tyres, and disconnect or tend the battery.
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Work in Quadrants
A square floor divides naturally into four. Assign each quadrant a purpose, vehicles, racked inventory, long-term household and current-access items, and keep the middle clear as a turning space.
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Photograph Each Zone and Keep the Map
On a rental this size, running for a year or more, a few phone photos taken the day you load will save hours later. Label cartons on the face that points at the aisle.
Our full storage tips guide goes further on protecting furniture and preparing equipment for storage.
Section 07
Climate-Controlled or Standard: Which 20x20 to Choose
We offer 20x20 space in both standard and climate-controlled configurations, though availability varies by location and climate control is less common at this size.
Standard Unit
Enclosed and secure, keeping weather and direct sun off everything inside. Interior temperature tracks the outside temperature, which across much of our footprint means well over 100 degrees in summer and below freezing in winter.
Fine for:
- Vehicles, trailers and towable equipment
- Tools, machinery and contractor materials
- Plastic totes, metal shelving and durable goods
- Lumber, fixtures and non-perishable stock
Climate-Controlled Unit
Temperature-regulated, holding an interior range year round. That protects against the extreme heat and hard freezes that warp wood, crack vinyl, degrade adhesives and damage electronics.
Worth it for:
- Electronics, screens and anything with a battery
- Wood furniture, cabinetry and millwork
- Business records, artwork and instruments
- Products with a temperature-sensitive shelf life
An Honest Limitation Worth Knowing About
Climate control at our facilities means temperature regulation. It does not mean moisture management, and we do not want anyone assuming otherwise on the strength of the name.
Temperature and moisture are two different threats. If you are storing something genuinely moisture-sensitive, such as documents, leather, upholstery, electronics or finished millwork, a temperature-regulated unit addresses one of those and not the other. Handle the second yourself: seal items in airtight containers rather than cardboard, add desiccant inside them, and keep everything off the concrete on pallets or risers. Those steps cost very little and do more for moisture-sensitive goods than any unit type will.
At this size, where a single tenant may be storing an entire inventory, that distinction is worth acting on rather than noting.
More detail is on the climate-controlled storage page.
Section 08
What a 20x20 Storage Unit Costs and How to Think About Value
What a 20x20 costs depends on your market, the specific facility, whether the unit is climate-controlled and what is available when you book. Rather than publish a range that goes stale, we point you at live pricing for the locations near you.
The Cost Logic That Does Not Change
- Larger units cost less per square foot, but the curve flattens at the top of the range. The saving from stepping up is real between small units and much smaller between large ones.
- Availability is the real constraint at this size. There are far fewer of these than there are 10x10s, and they do not come free often. If one is available where you need it, that matters more than a small price difference.
- Compare against commercial rent, not against other units. For a business, the useful comparison is the price per square foot of warehouse or flex space in your market, plus its lease term, deposit and build-out. This is usually not close.
- Two units can beat one. Check a 20x20 against two 10x20 units at the locations near you. One is simpler; two are sometimes cheaper and let you separate what you need from what you do not.
What Is Included, and One Thing We Cannot Do
Every rental includes a free lock, month-to-month terms with no long-term contract, and 24/7 gate access at nearly all locations. A protection plan is required at checkout at all of our facilities. Check first whether your existing business or homeowner policy already extends to goods stored off premises, and read your rental agreement for what the plan does and does not cover.
Our facilities are fully automated and unstaffed. You rent online, your gate code arrives by email and text, and you go straight to the unit. Because nobody is on site, we cannot accept deliveries on your behalf. That matters more at this size than any other, because businesses renting 20x20 space often assume inventory can be shipped straight to the unit. It cannot. If your operation depends on that, this is not the right fit, and it is better to know now. More on how our facilities work is on the why choose 10 Federal Storage page.
How Big Is a 20x20 Storage Unit?, Frequently Asked Questions
A 20x20 is 20 feet on each side, for 400 square feet of floor. With 8-foot ceilings that comes to 3,200 cubic feet, close to the dimensions of a residential two-car garage.
About 845 medium cartons wall to wall, five layers high, with nothing else inside. Leave an aisle and the figure is 590 to 600. Alongside a large household's furniture, plan on 250 to 300.
Yes, with room to open the doors on both. At 240 inches of width two vehicles at roughly 72 inches each leave about eight feet to divide between the middle and the sides. Confirm the roll-up door opening before booking.
Very close. Most residential two-car garages run about 20 by 20 or 22 by 22 feet, so a 20x20 unit is a fair approximation, with the caveat that the roll-up door is narrower than a garage door.
Both are 400 square feet. A 20x20 is a room you can lay out and work in; a 10x40 is forty feet of length and ten feet of width. Choose the 10x40 only if you are storing something longer than 20 feet.
Sixteen to twenty standard pallets on the floor with room to move between them, and considerably more if racked. A pallet jack can turn in a 20-foot square; a forklift cannot.
A six to seven bedroom home outright, or the contents of two ordinary apartments kept separate down opposite walls with an aisle between them.
Figures on this page assume 8 feet, consistent with the rest of the range. Confirm the specific unit before booking if you are stacking high or storing anything tall.
No. A storage unit is for storage rather than premises, so it cannot be used as a workshop, for business operations or for anything requiring utilities. You can access and load, which the square floor makes straightforward.
It depends what is going in. Choose temperature regulation for electronics, wood, documents, artwork and temperature-sensitive stock. A standard unit is fine for vehicles, tools and durable goods. Our climate-controlled units regulate temperature only, so seal moisture-sensitive goods either way.
Reserve a 20x20 Storage Unit Near You
A 20x20 is a two-car garage without the house attached. Two vehicles fit side by side with room to open both doors, or a large household fits with an aisle, or a business gets 300 linear feet of shelf and a square floor that is easy to lay out. The square proportion is the point: nothing about this unit forces you into a corridor.
See available 20x20 units and pricing Compare all unit sizes
