Thanks for your question. The Sterilite Medium Ultra Bin measures 13 3/4" L x 10 3/4" W x 5" H.
No, not by default design. However, you can make them stackable and sturdy, and you don't even need an engineering degree to make it happen! (I have one just to be safe.) So here's what I did for mine: Notice the U-Shaped slot on the inner rim of the basket near each corner? Also notice how they line up perfectly with each other? Coincidence? I think not. So while you're at Home Depot, go over to the Millworks area and pick up a 48inch x 7/16 inch no frills wooden dowel. Should cost you around 88cents. Oh yeah, have to calculate for inflation. Bring a dollar bill, just to be safe. Then take the dowel home and line it up between the slots, and mark it. Now cut it, twice, and drop each new piece into the slots. Should create a crossbar of sorts (on each side of the lower basket), so you can stack your other basket on top. I *HIGHLY* suggest and recommend not stacking them ANY HIGHER than 3 vertically. Light weight, Heavy weight, NO weight, It doesn't matter. 3 is the magic number. Once you reach 4, your basket-castle get's a little..... shaky. If you absolutely MUST stack higher than 3, OR if you plan on putting heavy stuff into them, then skip the Millworks department and instead make a beeline for the sheet metal area. Everbilt has a big "Bar, Tube, Rod and Cube" display at my HD. Pick up a 7/16 (if they have it in stock. If not, get a 1/2 inch) Aluminum Tube (or a Rod, if that's all they have), and cut them in the same fashion as explained for the wooden dowel. *BAM!* Now your Leaning Tower of Sterilite is just a little more stable. Anyways, I know I ramble a little, but I hope this helped you (and some people in the future, too) and your mission to be stacked. Good Luck.