Find The Answer To The Commonly-Asked Question, “Why Do Lego Sets Have Extra Pieces?”

There is a good chance you have opened a pack of Legos to find extra pieces. If you are like me, you have wondered why extra pieces are included in a set with very precise instructions. I have finally found the answer to this question.

Once you finish my guide, you are going to know:

  • Why extra Lego pieces are included in a set.
  • How you can benefit from those extra pieces.
  • Other Lego masters’ opinions of these extra pieces.

One fact is that these pieces come in handy as replacement components. This works for me because I would lose my head if it was not attached to my shoulders.

I have put together a guide that answers the most-asked question, “why do Lego sets have extra pieces?

Why Do Lego Sets Have Extra Pieces? The Mystery Solved

As a Lego master myself, I decided to explore the mystery of extra pieces. The instructions are precise down to the last detail, so I have been left wondering what to do with those extra pieces. Was it a mistake? Do I discard them? Of course, I am glad I never discarded those extra pieces because it turns out they are pretty useful.

You are finally going to find the answer to the question, “why do Lego sets have extra pieces?” Actually, you are going to find several answers to this Lego mystery.

The Bags Are Counted By Weight

It's hard to calculate the exact number of Lego pieces when you count them by weight.

When Lego packs the pieces into a bag, this is done automatically by weight rather than exact count. It is also done by machines that may not detect a missing piece.

Every piece is important when you are following the instructions to build an exact model. Can you imagine receiving a pack of Legos with key components missing? I love creating and building with Legos, so I would be pretty upset if a piece I really needed was missing from the set.

Lego understands that all the pieces are important, so it is easier to add additional small pieces to the set than to replace them all later. After all, it is better to have a few extra pieces than to not have the piece you need at all.

To quote The Brothers Brick,

“The robots are programmed to know the weight of each LEGO element and which elements are supposed to go in each bag. The smaller elements can be problematic in regards to the margin of error.”

Why Are The Extra Pieces Always The Smaller Components?

One thing I have noticed is that the extra pieces are always smaller. Why is it always the smaller pieces? Why do I not receive larger components as extra pieces? Once again, the answer is tied to the weight of the bags.

Remember, a machine is packing the bags for each Lego set, and the machine is counting the weight rather than the number of pieces. The smaller pieces do not weigh as much, so it is harder to get an accurate count per bag.

To quote Belle-Ve Bricks,

 “Now imagine that you have to rely on machinery to count out and pack the pieces based on weight alone. When something weighs that little it’s going to be hard to achieve 100% accuracy all of the time. LEGO have taken the stance, it’s better to be over than under when it comes to these tiny pieces.”

I think this makes a lot of sense as to why the extra pieces are smaller. A machine is not going to detect a missing small piece because it does not weigh as much as a large piece. Adding a few extra pieces is a great way to ensure all the important components are present.

What To Do With Those Extra Pieces

There are several options if you have extra pieces of Lego

Now that you have the extra Lego pieces, you are probably wondering what you should do with them. I have at least two ideas for these extra pieces, and you may have other ideas yourself.

Use Them As Replacements

If you are like me, you have lost many small Lego pieces in your lifetime. It is frustrating because it is hard to find those pieces. In fact, you may never find those pieces at all.

Before you pull your hair out in frustration, you can pull out an extra piece to complete your set. Now, you can finish building your Lego masterpiece.

Tweak Your Current Design

There are times when I like to try something different from the original design on the box. I follow the instructions to get the base of the design, but I may add a few extra pieces to tweak the current design.

You can use a few extra pieces to add your own personal touch to the design, but you want to keep a few in the bag to replace any lost pieces.

Keep These Pieces Safe

Whether you are replacing lost pieces or tweaking your design, it is important to keep these pieces safe. After all, you never know when you are going to need an extra piece.

I have a plastic bin full of labeled Ziploc bags of extra pieces. This way, I know which pieces go to which Lego set.

How I Can Benefit From Those Extra Pieces

With receiving additional pieces of Lego you also receive additional benefits

You now know that those extra pieces come in handy. I may not have known why we needed extra pieces at first, but I still found them to be useful for my projects.

Replacing Lost Pieces

We all know it is not uncommon for me to lose Lego pieces, and I am sure other Lego masters have the same problem. It is easier to pull out a spare piece than it is to stress over the situation.

Adding To The Current Set

Remember, you can also add the extra pieces to your current set. I do not add to the set all the time, but I have been known to change up a design with my extra pieces.

Use With Other Sets

There is always a chance a spare piece could work with another Lego set, especially if it is a small, basic piece. I have dipped into other spare pieces to replace a component or change a design in a different set.

Other Lego Masters Share Their Thoughts On Lego Sets and Extra Pieces

I love learning the opinions of other Lego masters, and there are several videos and blogs I would recommend to other Lego fans.

Large Lego Sets Be Like…

SpitBrix explores Lego sets with many repetitive pieces by counting down the sets with the largest quantity of a single piece. I think this is interesting because I never realized how many sets have repetitive pieces.

The Extra Pieces

There are plenty of Lego masters who have wondered about the extra Lego pieces, and this includes Blockie Talkie. This video sheds light on why Lego has a great reputation when it comes to including all the pieces.


You now have several answers to the question, “why do Lego sets have extra pieces?” The answers make a lot of sense because a machine cannot detect missing pieces, and it is not uncommon for even the most experienced Lego master to lose a piece. Whenever you buy a new Lego set, be sure to keep those extra pieces in a safe place.

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