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I am trying to do a science project and I need the exact weight of one of the LEGO pieces. I am using it as a counter balance on my scale. What is the weight of a 1x4 LEGO brick?

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4 Answers 4

I have a 1x4 brick that weighs 1.7grams. My scale measures to the nearest 0.1gram. A 1x4 plate (one third the height of the brick) weighs 0.7grams. Together they weigh 2.3grams, so the actual weight of each part is likely 1.65 to 1.70 grams and 0.65 to 0.70 grams respectively based on that. These were standard parts, I don't think that the color will matter within the measurement accuracy, however, a transparent part is made from a different material and will likely be different.

I also grabbed 4 1x4 (standard, nontransparent) bricks at random and collectively they weighed 6.4grams. I made sure that they all appeared to have the same type of mold. I found one that had small depressions on the tube side (likely for mold venting) and excluded this (it weighed about 0.05 to 0.1grams less than the others). So this suggests that this particular type weighs, 1.6 grams on average. I'm not sure what the expected variation would be, but with a little statistics you could figure out how many you would need to measure to get a most likely value. For your purposes, I recommend that you use 1.6 grams if the three tubes do not have a depression on the end (and 1.5grams if they do) and if you need to know better, take some measurements yourself (of the actual parts that you are using).

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"How much does a LEGO brick weigh?" is a seemingly simple question, but the answer quickly spirals into complexity.

I work with many hundreds of identical bricks fairly often. To count these out accurately I use high precision scales (0.01g), but I'm never confident about the counts.

Be aware that as well as variations in mold design (which other answers have pointed out), even pieces from the exact same place on the same mold can have different masses. Different colours of LEGO have different densities, so even for the same volume of plastic you'll get different weights.

I commonly come across sets with two different moldings, for example with the rods in the underside of bricks being hollow or not. The reason for this is that mold designs are changed when designs with better characteristics - typically plastic consumption, but possibly heat dissipation, flow attributes or other factors - are created. But manufacturing a mold costs a vast amount of money; the most expensive ones are over a quarter of a million dollars. Because of this large capital cost to produce molds, LEGO manufactures elements from different mold designs at the same time (plastic molds can be good for 10 to 250 thousand impressions, and might be refurbished rather than retired an the end of this run) and you have a world where your question can't be answered definitively.

Here's the best advice I can offer:

  1. weigh many identically-coloured bricks on a high-precision scale*
  2. before you do, inspect each brick to ensure that there are no mold variations
  3. divide the total mass by the number of bricks

*I have a kitchen scale that has 2 grams of precision, and a much smaller scale that works to 0.01g. Which is more precise? More accurate? How can you make one give more precise answers than the other?
If you go more precise that than 0.01g you're going to have to protect against noise introduced by fluctuations in air pressure (as it is, I have to be careful not to breathe on the 0.01g scales or the reading bounces around for a while). If you go to a jeweller's shop, you can see how they deal with this problem when they weigh gold and gems - they put a hood over the scale!

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Since it is for a science project, I would suggest you take the official weight and compare it to the weight you come on your own. This will not only get you your weight but will score your project higher. The best way to do this would be to take 100 pieces and weigh them on a postal scale (if your school doesn't have access to one, your parent's work might, or even the post office might do it for you). Then take the total weight and divide it by... 100!

Of course the more blocks you use the more precise your weight will be, but after a while it just get to be silly...

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In most cases you can find the weight of a brick from Bricklink an unofficial LEGO site that takes weight measurements from user submitted data. Bricklink states the 1x4 brick as 1.64 grams in weight.

LEGO bricks tend to be odd weights because the design process primarily focusses on the physical aspect. A 1x8 and 2x4 brick both have exactly eight studs, yet the weight between them differs by almost a gram.

In the interest of scientific accuracy, I would recommend weighing the bricks yourself with digital kitchen scales to confirm the weight.

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4  
Over the years the design of the bricks has changed in terms of the internal reinforcement of the bricks (as seen from the underside of the brick), so you'd definitely have to measure yourself. –  Eilon Apr 27 '12 at 5:01
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The best way to get an accurate weight measurement is to weigh a larger number of blocks and divide the total weight by the number of blocks. –  jan.vdbergh May 4 '12 at 8:44

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