Planning your move involves a lot of complicated calculations. Fortunately enough, determining what size moving truck you’ll need is generally one of the easier decisions. Many moving companies will estimate the weight of your items, charge accordingly, and then determine what size truck you’ll need. Others offer helpful moving tools that allow you to calculate the size of your truck. This can save you a lot of trouble in planning a move into your new home. But often enough people aren’t just moving their things into a spacious house, but into a storage unit where they’ll be paying a premium on space. Unfortunately, when it comes to calculating what size storage unit you’ll need you’re on your own.

Determining the size of your storage unit is an even more high-stakes decision than choosing the right truck size. While you only rent a truck for a one-way trip, you’ll probably be keeping your things in that storage unit for a few months and so any miscalculations will be compounded each month. Even if you’ve been able to find a cheap storage unit, rent one that’s too large and you’ll end up paying too much; with a unit that’s too small you won’t be able to fit all of your things.

But don’t worry: we can easily calculate the size of the storage unit you’ll need based upon the size of your truck—this saves you from having to reexamine your inventory when you move it into a new space, leaving the most complicated calculations to the moving company. “But wait,” you might say. “How can this be done? Trucks come in very different sizes than storage units, often only being described in terms of their length (12’, 16’, 22’, 26’) while storage units are described by length x width (5×10, 10×10, etc.). How do we reconcile the two?”

With just a little bit of math, my friend—and don’t worry, I’ll be the one manning the calculator. Here we go:

## Calculating the size of the storage unit

The secret is to convert everything into volume; cubic feet will be our measure. To do so (if you dozed off in middle school) all you need to do is multiply length x width x height. “But hold on,” you might be thinking. “Trucks are described in terms of length, while storage units are described in terms of length and width. What about the other measures?” Here we’ll have to use a few averages. The average height of a moving truck is 7’, while its width usually comes in at 7’ as well. Storage units generally range between 8-12 feet tall, so we’ll be using the median height of 10’ in our calculations. Remember, these figures are only averages. While they’ll probably give you a good idea of actual sizes, you should always verify measures with the moving company or storage facility. You can then plug those numbers into the equation we’ll introduce below.

So let’s determine the average volume of a moving truck. A 12’ truck will be 7’ wide and 7’ tall, so that’s 12’ x 7’ x 7’= 588 cubic feet. A 22’ truck will also be 7’ tall and 7’ wide, which gives us 22’ x 7’ x 7’= 1078cf.

And what about storage units? 5 x 10 units are generally 10’ tall, so that gives us 5’ x 10’ x 10’= 500 cubic feet. A 10 x 10 unit would also generally be 10’ tall, giving us 10’ x 10’ x 10’= 100cf.

Using simple calculations such as these we can match the cubic feet of the moving truck to the cubic feet of the storage unit—just make sure that the unit isn’t smaller than the truck. We’ve done the work for you in our table below.

 Truck Equation Volume Storage Unit Equation Volume 5×5 5’x5’x10’ 250cf 10’ 10’x7’x7’ 490cf 5×10 5’x10’x10’ 500cf 12’ 12’x7’x7’ 588cf 10×10 10’x10’x10’ 1000cf 16’ 16’x7’x7’ 784cf 10×10 ————— ———— 22’ 22’x7’x7’ 1078cf 10×15 10’x15’x10’ 1500cf 24’ 24’x7’x7’ 1176cf 10×15 ————— ————— 10×20 10’x20’x10’ 2000cf

But there’s one more thing we need to consider. Packing a storage unit isn’t the same as packing a moving truck. A moving truck goes from one place to another, unloads, and then you’re done. A storage unit on the other hand is typically rented for a few months, and during that time it’s very likely that you’ll need to get in to access your belongings. You might want to take things out and put them back or to swap them for other things. The above calculations were based on the pretense that you’d be filling your storage unit to capacity, just as you would a moving truck. But doing so would also make it extremely inconvenient to reach your items—you might need to take everything out just to grab one thing. If you’re entirely certain that there are only a few items you’ll need to access you can simply organize your unit so that they’re at the front. But if you have a decent number of items you’ll need to be able to get to that might not be possible, so we recommend leaving a corridor to the back of your unit. Another good idea would be to not stack things all the way to the ceiling—shorter stacks will make things more accessible.

So let’s adjust our calculations. To shorten the stacks in the storage unit, we’ll bring the height down to 6 feet then calculate the volume again. Then we’ll calculate the volume of the corridor. Our corridors will be three feet wide and will save three feet at the back of the room for storage. So our corridor’s size will be 3’ x (depth – 3’) x 6. Since a 10×10 unit is 10’ deep, the equation will be 3’ x (10’- 3’) x 6, simplified to 3’ x 7’ x 6’= 126cf. Then we’ll subtract that 126cf from the total volume of our unit (10’ x 10’ x 6’= 600cf), giving us 600cf – 126cf= 474cf. So if we want our items in to be easily accessible in our 10×10 unit, we’ve really only got 474 cubic feet of actual storage space. Here’s our table for an easily-accessible unit (we skipped 5×5 and 5×10 storage units, as those should be easy enough to access without a corridor or short stacks).

 Unit Equation Corridor Storage Volume 10×10 10x10x6= 600 3x7x6= 126 474cf 10×15 10x15x6= 900 3x12x6= 216 684cf 10×20 10x20x6= 1200 3x17x6= 306 894cf

Remember: these numbers are only for people who want easy access to all of their items in storage. You can always pack your items to use the full volume of the storage unit as demonstrated with the last table, or adjust the size of your corridor and the height of your stacks as you see fit. Indeed, if you organized your unit in this way you wouldn’t even be able to fit the contents of a 22’ or 24’ truck, as you can see in the table below.

 Truck Equation Volume Storage Unit Storage Volume 10×10 474cf 10’ 10’x7’x7’ 490cf 10×15 684cf 12’ 12’x7’x7’ 588cf 10×15 684cf 16’ 16’x7’x7’ 784cf 10×20 894cf 22’ 22’x7’x7’ 1078cf none 24’ 24’x7’x7’ 1176cf none

Brian Shreckengast is a writer at SelfStorageDeals.com, the price-focused search engine for finding cheap self-storage units. Learn more about storing and how to do it for cheap at the Self Storage Blog.