What is the density of Lego?

It’s 1.07 g/cm3 according to the ABS density (ABS is what Lego are made of). It’s slightly greater than 1 and is the reason why Lego bricks don’t float.

But it’s actually not that simple as Lego constructions are usually full of air.

Consider the most common Lego piece, the venerable 6141 (aka round plate 1×1), it can be carefully packed or just thrown together. Different values are valid depending on the arrangement and what you’re trying to use it for.

Arrangement of round plates Density (g/cm3)
Lego legal packing 0.55
Optimal packing 0.64
Bulk 0.42

Mode details about the computations.

Lego legal packing: a single round plate is about 0.113 g and occupies a space of 8^2*3.2\ mm^3

Optimal packing: here you put the plate in triangular tiling, so the space used by a single piece is \frac{\sqrt{3}}{4}*8^2*2*3.2\ mm^3

Optimal packing

Bulk: in a liter, you can put about 3735 round plates which translate into 422g/L or 0.42g/cm3.

100 most common lego pieces

There are several way to define what is a common piece. Ideally, that would be the based on the number of each type of piece available in the entire universe.

But given that the Lego Group doesn’t release how many pieces of each type were produced and that it’s hard to estimate how many ended up in vacuum cleaner and ultimately incinerated, we’ll have to accept some approximation.

Here I’m just taking a list of 5400 recently released lego sets (let’s say in the past 15 years) and count how many of each type of piece was in each set. Based on that, here is a list of the 100 most common pieces:

 

6141 6141
3023 Plate 1 x 2 3023
3004 Brick 1 x 2 3004
2780 Technic, Pin with Friction Ridges Lengthwise WITH Center Slots 2780
3024 Plate 1 x 1 3024
3005 Brick 1 x 1 3005
3003 Brick 2 x 2 3003
54200 Slope 30 1 x 1 x 2/3 54200
3710 Plate 1 x 4 3710
3069b Tile 1 x 2 with Groove 3069b
3020 Plate 2 x 4 3020
3001 Brick 2 x 4 3001
3010 Brick 1 x 4 3010
3022 Plate 2 x 2 3022
6558 Technic, Pin 3L with Friction Ridges Lengthwise 6558
2412b Tile, Modified 1 x 2 Grille with Bottom Groove / Lip 2412b
3062b Brick, Round 1 x 1 Open Stud 3062b
3021 Plate 2 x 3 3021
3666 Plate 1 x 6 3666
43093 Technic, Axle Pin with Friction Ridges Lengthwise 43093
3070b Tile 1 x 1 with Groove 3070b
3040b 3040b
2431 Tile 1 x 4 2431
3068b Tile 2 x 2 with Groove 3068b
3623 Plate 1 x 3 3623
3622 Brick 1 x 3 3622
32062 Technic, Axle 2 Notched 32062
3009 Brick 1 x 6 3009
4274 Technic, Pin 1/2 4274
3795 Plate 2 x 6 3795
3002 3002
3039 Slope 45 2 x 2 3039
6636 Tile 1 x 6 6636
3713 Technic Bush 3713
2420 Plate 2 x 2 Corner 2420
4070 Brick, Modified 1 x 1 with Headlight 4070
3660 Slope, Inverted 45 2 x 2 3660
4519 4519
32123b 32123b
3665 Slope, Inverted 45 2 x 1 3665
3941 Brick, Round 2 x 2 with Axle Hole 3941
4032a 4032a
3460 Plate 1 x 8 3460
2357 Brick 2 x 2 Corner 2357
32054 Technic, Pin 3L with Friction Ridges Lengthwise and Stop Bush 32054
3034 Plate 2 x 8 3034
85984 Slope 30 1 x 2 x 2/3 85984
3794b Plate, Modified 1 x 2 with 1 Stud with Groove (Jumper) 3794b
3700 Technic, Brick 1 x 2 with Hole 3700
98138 Tile, Round 1 x 1 98138
3794a 3794a
4162 Tile 1 x 8 4162
59900 59900
3008 3008
4589 4589
2877 Brick, Modified 1 x 2 with Grille (Grill) 2877
87087 Brick, Modified 1 x 1 with Stud on 1 Side 87087
30136 Brick, Modified 1 x 2 Log 30136
6536 6536
2654 Plate, Round 2 x 2 with Rounded Bottom (Boat Stud) 2654
44728 Bracket 1 x 2 – 2 x 2 44728
87580 Plate, Modified 2 x 2 with Groove and 1 Stud in Center (Jumper) 87580
6091 Brick, Modified 1 x 2 x 1 1/3 with Curved Top 6091
59443 59443
32028 Plate, Modified 1 x 2 with Door Rail 32028
4286 Slope 33 3 x 1 4286
4477 Plate 1 x 10 4477
33291 33291
3673 Technic, Pin without Friction Ridges Lengthwise 3673
87079 Tile 2 x 4 87079
2540 Plate, Modified 1 x 2 with Handle on Side – Free Ends 2540
3705 Technic, Axle 4 3705
50950 Slope, Curved 3 x 1 No Studs 50950
6541 Technic, Brick 1 x 1 with Hole 6541
970c00 Hips and Legs 970c00
11477 Slope, Curved 2 x 1 No Studs 11477
32013 Technic, Axle and Pin Connector Angled #1 32013
60478 Plate, Modified 1 x 2 with Handle on End – Closed Ends 60478
53451 Barb / Claw / Horn – Small 53451
3037 Slope 45 2 x 4 3037
2456 2456
48336 Plate, Modified 1 x 2 with Handle on Side – Closed Ends 48336
32073 Technic, Axle 5 32073
3031 Plate 4 x 4 3031
3749 Technic, Axle Pin without Friction Ridges Lengthwise 3749
63864 Tile 1 x 3 63864
3065 Brick 1 x 2 without Bottom Tube 3065
32523 Technic, Liftarm 1 x 3 Thick 32523
32316 Technic, Liftarm 1 x 5 Thick 32316
3032 3032
3437 3437
30374 Bar 4L (Lightsaber Blade / Wand) 30374
32140 32140
15573 Plate, Modified 1 x 2 with 1 Stud with Groove and Bottom Stud Holder (Jumper) 15573
3832 Plate 2 x 10 3832
4740 Dish 2 x 2 Inverted (Radar) 4740
3298 Slope 33 3 x 2 3298
4081b Plate, Modified 1 x 1 with Clip Light – Thick Ring 4081b
30414 Brick, Modified 1 x 4 with 4 Studs on 1 Side 30414
41677 Technic, Liftarm 1 x 2 Thin 41677
32524 Technic, Liftarm 1 x 7 Thick 32524