One of the most frequent questions I hear when people rent a storage unit for the first time is “How much storage space do I need?”

There are all kinds of charts and graphics on various self storage websites the claim to tell you exactly what size storage you’ll need based on how big your house is or how many boxes you are planning to store, but the truth of the matter is no one really knows.

I like to use my move to Phoenixville, Pennsylvania as the best example.

We decided to rent a truck and move ourselves rather than paying movers. We knew we had a lot of stuff, even though we only had a two bedroom apartment. We collect board games, have a lot of DVDs, and had more boxes of books than I want to admit to owning. And we had our furniture.

In hindsight, we shouldn’t have moved some of the furniture, but we tried.

So I went to one of the calculators and did some math. We had two bedrooms, so if we got the truck one size larger than what they recommended, we’d have plenty of room, right?

Wrong!

we packed everything ourselves, but then hired professional movers to pack the truck. Those guys were amazing in filling in nooks and crannies and packing every square inch of the truck. And we still didn’t have enough room. A couple boxes got shoved in the cab with the friend who was driving the truck for us. A few more got stuffed into the trunk of car we were driving out and several more got thrown away at the last minute. We even ended up leaving behind a futon and some small tables.

So why was the estimate so terribly wrong?

The people who make those estimates assume that everything is going to fit into neat little squares and can have stuff piled on top of it and around it. But when you have an overstuffed living room set and six office chairs (because we wanted comfortable chairs for our game room), they don’t fit together nicely and they take up a lot of space.

Likewise, our seven (7!) bookcases could have some boxes set in the bottom of them to keep them steady, but the top half of the book cases was empty space that only the lightest things could go in. Otherwise, it shifts in moving and you break the bookcase. The artwork and the television had to be packed upright, so the glass didn’t break and couldn’t have, say, an office chair’s wheels pressing into them.

We needed far more truck than our 1,200 square-foot-apartment indicated.

Ultimately, those storage calculators are good for getting a vague idea of what amount of space you need, but then you need to take a realistic look at your stuff and decide if that’s right for you. And talk to your storage professional. A good storage facility is never going to try to talk you into something larger than you need, but they will ask you to think about things you may not have considered.

Do you need to be able to get things in and out regularly?

If so, you might want to go bigger and leave yourself walking room. No one wants to have to unpack half the unit just to get out the turkey roasting pan.

Do you have fragile or delicate things that need special handling?

We store some of our game materials in our storage unit so they needed to be on shelving and shelves take up extra space. Plan ahead to decide how yo will get things into the unit and back out again.

Do you have oversized or oddly shaped furniture?

The wheel base on office chairs, an overstuffed sofa and even the presence of glass on your tabletops can impact the way you need to store it. Rocking chairs, recliners and even dining room chairs can take up extra space.

When you get to the storage facility, have an idea of the amount of space you will need, but talk to your storage professional as well. They may be able to offer packing tips that save you space and money.