I'm currently working on a large MOC (for me at least) and it's got me interested in finding out just how many of a given element a cup can hold or even a box, and is there a difference in economics between the two especially with the bump in prices this year? I've done some measuring and felt I might not be the only one interested in the results, so here they are! I'd love to hear from you if you have additional data points that I've missed. I mainly focused on the basic parts that I had sufficient quantity on hand to measure.
First, the methodology: I used the large cups. For filling, I'm aware there are all kinds of great strategies to maximize part count. The quantities arrived at here are simply based on enough shaking to get the parts to settle and nothing more. When shopping for 2000 2x4 bricks, I'm probably not going to spend any more time than that anyway. Just be advised, you can do better than this if you have the time or inclination.
If you've never bought a box, these are pre-filled. I'm not guaranteeing these counts to be accurate, but they are representative of what I've received in the past, which is almost, but not quite, filled to the top. That is, I'm pretty sure LEGO doesn't shake these to maximize part count, so there is some settling during shipping. The 2x4 brick count should be pretty close since it was recently purchased, but the others I just filled to the same level. I'd love to know if you've picked up a box recently and have a more accurate count.
As of this year, the price for a large cup in the US is $15.99 while a box will set you back $100. Interestingly, except for the 2x8 brick, these prices appear to work out to roughly the same price per piece. In the case of 2x8 bricks, there appears to be about a 10% savings purchasing by the cup (which makes me wonder if my count is off for the box quantity). If you're good at optimizing part count in a cup, it appears the cup will always save you money over a box regardless of the piece and if you're getting a cup refill you'll save a little more.
Size: Cup qt, Box qt (- where quantity is unknown)
2x8: 45, 250
2x6: 55, 350
2x4: 95, 630
2x3: 140, -
2x2: 210, -
1x4: 200, -
1x2: 450, 2700
1x1: 990, -
Size: Cup qt
1x2 with 1 stud: 1270
Size: Cup qt
Would I like a box of 1x2 brick with masonry design? Sure, especially since all the LEGO store by me got was the light bley, wanted the earth orange and sand yellow versions too, but that also means taking it out of the hands of many others that want that brick as well. Luckily the LEGO store I frequent did not allow for a purchase of a box because that was all they got sometimes. Now they have not had them again, so I'm grateful they restricted it to cups.
interesting stats though.