Whether you are anticipating a move or just completed one, nothing seems as precious as moving boxes.

Dragging those invaluable cardboard containers—which you spent weeks collecting from neighbors, co-workers, packing stores, and maybe an upscale supermarket or two—to the curb is kind of like parting with your favorite pair of jeans. Separation is tough. There they are: your lovely, sturdy receptacles, just sitting there. So potentially useful.

But you’ve got to clear the clutter, right? Well, here’s the thing: Some boxes are worth keeping. Which ones, you ask? Read on!

Size matters

When it comes to moving boxes, there is a perfect size—and it might not be what you think.

Small boxes “are easy to carry and load,” says Irwin, noting that they’re especially helpful if you do most of your moves yourself. “If a box becomes too heavy, the items inside can tear it up.”

Typically, you can get rid of your largest boxes—including appliance boxes, wardrobe boxes, and commercial bin–size boxes.

“It is almost impossible to carry and load those boxes,” Irwin says. And even when they’re flat as pancakes, those massive boxes are tough to store.

Put your needs first

Once you’ve stowed away the small (and movable) boxes and tossed the biggest ones, you’ll be left with a mishmash of sizes and shapes. So, consider your needs.

Not everything is going to fit in a small box. Like, um, your sea kayak. Or your TV. Or lighter, oddly shaped items such as lamps, large vases, and serving trays.

For those smaller items, do a test run and see what can fit into your medium-size boxes, but keep this in mind: Don’t cram a million heavy small things into a large box if you want an easy move.

Let it go, let it go

As a society, we have a strange habit of holding on to the box something came in. From the giant flat-screen TV box to the boxes for all of our small appliances, you’re likely holding on to at least half the boxes—and all the packing materials—for everything you own.

The thing is, those boxes will hold only one thing. And while your blender might feel very secure in its perfect egg carton shell and custom-fit box—if you go this route—you’ll be moving twice as many boxes as you need to.

Unless it’s something incredibly fragile or incredibly dear to your heart, do yourself (and your storage space) a favor and toss those boxes.

If you can’t bring yourself to toss, at least chuck the packing material.

“It is so easy to find new packing material when you need it,” Irwin says.

Don’t want no scrubs

Finally, take a hard look at your saved boxes. Your move might have been a battle—but if those boxes have battle scars, it’s time for the recycling bin.

Bottom line: “If the box is torn, dirty, or crumpled, throw it away. You do not need it,” Irwin says.

And don’t forget to give the inside a good whiff. Seriously. If you moved cleaning products, your spice cabinet, or your unwashed clothes, the cardboard might absorb the smell forever. And if it smells now, whatever you pack inside could end up smelling later.

Once you’re playing for keeps, cut the tape on both sides, fold your boxes flat, and store them in a stack in a dry environment until next time.