Storage unit sizes at auction range from tiny 5x5 closets to massive 10x30 garages. Most buyers develop a size preference over time — some swear by small units, others won't touch anything under a 10x10. I've bought all sizes extensively, and the answer to which storage unit size wins at auction isn't as simple as "bigger is better."
Here's the real data on how unit size affects your bottom line.
Understanding Storage Unit Sizes
Before we compare, let's make sure we're talking about the same thing. Storage unit dimensions are listed as width by depth, measured in feet.
- 5x5 (25 sq ft): Walk-in closet size. Fits a few boxes, small furniture pieces, maybe some shelving. These are the smallest units you'll commonly see at auction.
- 5x10 (50 sq ft): Half a standard garage bay. Fits a couch, a few boxes, some loose items. Common at auction and often overlooked.
- 10x10 (100 sq ft): The most common storage unit size. Equivalent to a small bedroom. Fits the contents of a 1-2 bedroom apartment. This is the bread-and-butter unit at most facilities.
- 10x15 (150 sq ft): Between a bedroom and a garage. Fits the contents of a 2-3 bedroom home. More inventory, more potential, more work.
- 10x20 (200 sq ft): Single-car garage equivalent. Often used by people storing a household's worth of belongings or by small businesses. The largest units you'll commonly bid on.
- 10x30 (300 sq ft): Rare at auction but they exist. Usually commercial storage. Can contain vehicles, large equipment, or massive inventory loads.
Average Values by Storage Unit Size
These are rough averages based on my experience and what I've seen from other buyers. Your market will vary, but the relative proportions tend to hold.
5x5 units
- Average winning bid: $20-$75
- Average resale value of contents: $50-$300
- Hit rate (profitable units): ~50-60%
Small units are a coin flip. Half the time you're pulling out boxes of paperwork, seasonal decorations, and old clothes worth nothing. The other half, someone packed valuables into a small space — jewelry, electronics, collectibles, tools — and the return relative to your investment is excellent.
10x10 units
- Average winning bid: $75-$250
- Average resale value of contents: $200-$800
- Hit rate (profitable units): ~55-65%
The 10x10 is the sweet spot for most buyers. Enough volume to contain meaningful inventory, but not so much that hauling becomes a multi-day project. The bid prices are manageable, and you can usually evaluate the contents reasonably well from door photos because the unit isn't so deep that everything is hidden.
10x20 units
- Average winning bid: $150-$500
- Average resale value of contents: $400-$2,000
- Hit rate (profitable units): ~50-60%
Large units have higher absolute value but also higher risk. More volume means more furniture (often low-value), more garbage to dispose of, and more time to haul and sort. The big wins come when a 10x20 is packed with organized boxes, tools, or commercial inventory rather than household furniture. For a deeper look at estimating what's inside before you bid, check out the guide on how to estimate storage unit value.
Haul Cost Differences by Size
This is where unit size math gets real. The cost to haul and dispose of unwanted items scales roughly with unit size, but not linearly — it actually gets worse as units get bigger.
5x5 haul costs
You can clean out a 5x5 in your personal vehicle most of the time. A single car trip or a small SUV load handles it. Dump fee: $0-$30 if there's anything to toss. Total haul overhead: $0-$50. You might not even need a truck rental.
10x10 haul costs
You typically need a pickup truck or small van. One to two loads for most units. If you don't own a truck, budget $50-$100 for a rental. Dump fee: $30-$60. Total haul overhead: $50-$150.
10x20 haul costs
You need a full-size truck or cargo van, and you'll likely make multiple trips. Some 10x20 units require a box truck. Rental: $75-$150/day. Dump fees: $60-$120 (often multiple dump runs). You might need a second person for heavy furniture. Total haul overhead: $100-$300.
The critical takeaway: haul costs as a percentage of unit value are highest for large units that turn out to be furniture-heavy. A 10x20 full of couches, mattresses, and particle board furniture might cost $200+ to haul and dispose of, yielding almost nothing in resale value. That's a scenario where you lose money even if you only paid $50 for the unit.
Time Investment by Unit Size
5x5: 1-3 hours total
Quick cleanout, quick sort. You can evaluate, haul, and sort a 5x5 in a single morning. Listing time depends on what you find, but the physical work is minimal. This is the size that lets you process multiple units in a single day if you're buying volume.
10x10: 3-6 hours total
A solid half-day commitment. Loading the truck takes 1-2 hours, sorting takes another 1-2 hours, and you'll spend time listing items over the next day or two. This is manageable as a weekend side project — one 10x10 per week is a sustainable pace for part-time buyers.
10x20: 6-12+ hours total
This is a full day or more. Loading can take 3-4 hours, especially if there's heavy furniture. Sorting takes another 3-4 hours. You'll need dedicated sorting space — your garage or a rented area — because the volume is significant. Don't bid on a 10x20 if you don't have the next two days clear to process it. Facilities enforce cleanout deadlines, and a 10x20 you can't empty in time becomes an expensive problem.
ROI by Unit Size: The Real Comparison
Raw value doesn't matter. What matters is return on investment — profit divided by total cost including your time.
5x5 ROI profile
Best case: Buy for $30, haul for free, sell contents for $250. That's a 700%+ return in 2 hours of work.
Worst case: Buy for $50, contents are worthless paperwork and holiday decorations. You're out $50 and an hour of time. Not painful.
Typical case: Buy for $40, sell $100-$150 worth of items, net $60-$100 profit after disposal. Solid hourly rate for 1-2 hours of work.
10x10 ROI profile
Best case: Buy for $100, haul for $75, sell contents for $800. $625 profit on 5 hours of work = $125/hour.
Worst case: Buy for $200, haul for $100, sell contents for $150. You're down $150 and a half-day. Stings but survivable.
Typical case: Buy for $125, haul for $75, sell $350-$500 worth of items. $150-$300 profit. Good return for a day's work.
10x20 ROI profile
Best case: Buy for $200, haul for $150, sell contents for $2,000. $1,650 profit. This is the unit that makes your month.
Worst case: Buy for $400, haul for $250, sell contents for $200. You're down $450 and two days of work. This is the unit that makes you question your life choices.
Typical case: Buy for $200, haul for $150, sell $600-$1,000 worth of items. $250-$650 profit, but over 8-12 hours of total work.
Analyze listings before you bid — AuctionData scores units on StorageTreasures, LockerFox & StorageAuctions using AI image analysis, neighborhood income data, and keyword signals.
When to Bid on Each Size
Bid on 5x5 units when:
- The price is under $50 and you can see anything identifiable (boxes with labels, visible brand-name items, organized contents)
- You want quick turns with low risk — process multiple small units in a day
- You're a beginner and want to learn without risking serious money
- The unit is in a higher-income zip code (small units in upscale areas often contain higher-value items per square foot)
Bid on 10x10 units when:
- Photos show dense packing with visible variety — boxes, electronics, tools, organized shelving
- You can see through the front layer and identify items worth pursuing
- The bid price stays under $200-$250 and the contents justify it based on what's visible
- You have a truck available and a clear afternoon for cleanout
Bid on 10x20 units when:
- You can identify high-value items from the photos — tools, commercial equipment, organized inventory
- The unit shows signs of business storage rather than household storage (shelving, uniform boxes, labeled containers)
- You have two days clear for hauling and sorting
- You have sorting space available (garage, rented storage, warehouse)
- The math works even if 40% of the contents are disposal items
Skip large units when:
- The front is dominated by mattresses, couches, and large furniture
- Everything visible is disorganized and thrown in — suggests the renter was in a hurry and the contents are likely low-quality
- You don't have reliable hauling capacity for the full volume
- You're already sitting on unsold inventory from previous units
Understanding what drives value in abandoned units is crucial regardless of size. For context on how neighborhood data factors in, read about abandoned storage unit value.
My Size Strategy
After years of buying across all sizes, here's what I've settled on:
70% of my bids are on 10x10 units. They're the best balance of value, risk, and time. I can evaluate them well from photos, haul them in a single trip, and sort them in an afternoon. The math works consistently at this size.
20% of my bids are on 5x5 and 5x10 units. I cherry-pick small units when the price is low and I can see specific items worth pursuing. These are my low-risk, quick-turn plays. Some of my best per-hour returns have come from $25 small units with a single valuable item inside.
10% of my bids are on 10x20+ units. I only bid on large units when the photos are clearly promising — visible tools, organized commercial contents, or identifiable high-value items. I never bid on a 10x20 that looks like a household dump. The downside risk on a bad large unit is too high relative to the time and haul costs.
Unit size is one variable in the evaluation equation, but it's an important one. Don't chase big units because they feel like more value. Don't dismiss small units because they feel like small potatoes. Run the math on every listing: what's the realistic value of what you can see, minus your total cost to acquire, haul, and dispose? The size that gives you the best answer to that question is the size you should bid on.