What Size Should A Bonsai Be?

Wondering what size your bonsai should be in a very common question for beginners. The truth is your bonsai tree can be any size you want.

There are no rules about how big or small a bonsai tree should be. So long as your tree is in proportion, it will look good.  

What Size Bonsai Do We Need?

The aim is to have a bonsai tree that visually looks like a miniature version of a full size tree in a pot. You do not need to get too caught up on the exact measurements of this.

The style and species are all going to play a role in how big or small your bonsai tree can be. Different species will be more suited for different sizes. They may have larger leaves and need to be an overall bigger tree to look in scale, or they may have really small foliage that can look really good as a tiny tree.

The size of your bonsai pot and how often you prune will pay a role in your trees size as they can affect the speed at which your tree grows. This can be good if you are trying to keep your tree small, but if you are looking to let your tree get bigger, you will need to have a bigger pot and prune less.

Size Classifications Of Bonsai

Size classification of bonsai trees does exist, but these are only used in Japanese bonsai exhibitions. They are used to just separate trees into categories so they can be grouped together and judged for the competition.

They could do this by tree style or species, but they feel the size categories are more appropriate.

Sometimes a bigger bonsai tree can just have a presence in a room that will dominate other trees around it that may be a bit smaller. If you’ve ever seen larger bonsai trees in real life you will understand the awe of them. By grouping trees by size it helps to eliminate this advantage.   

The bonsai trees are measured from the soil level at the lip of the pot up to the top of the tree.

I will not be going through the different height classifications here as although they are important and useful, they really don’t matter unless you are trying to enter a tree into one of these exhibitions.   

The exact size of your bonsai tree is not important, it’s more important to make sure it is in scale and has good proportions all over.

Should Your Bonsai Be Bigger?

Some people believe bonsai’s need to be super small, which can be true; however, you can also get some quite large ones.

Going a bit bigger can often be better. A bonsai tree that is larger will usually have more growth and give you more options to work with.

The larger size bonsai trees will also just look more powerful. They are more likely to have thicker trunks and just give that visual dominance that draws people towards it.

If you look at the bonsai trees in Japan, they are often a lot larger than you realise. They can often be at least 1m tall, maybe even taller at times. When you look at bonsai tree in a book or on instagram it is hard to judge its size of it as there is often nothing to reference it against.

When you start to watch videos and see people stood next to them, working on them, you will realise they can be quite large. Have you ever seen 2, maybe even 3 people move a bonsai tree before? That shows they are a decent size if they can’t be lifted by 1 person.

If you also start to study a lot of the yamadori, not just Japanese, but form anywhere, some of the most amazing pieces are pretty big.

Just start paying attention to the people stood next to the bonsai trees you are looking at online. You will really start to see your own trees are probably tiny in comparison.  So do not get too worried about going a little bigger.

If you look at bonsai trees from Vietnam you can see they push this even further. Their bonsai trees are often huge. It could be argued that they are almost full size, or at least garden tree size. However, they are potted trees and they do receive bonsai techniques to keep them in shape, so by definition, they are still bonsai.  

Should Your Bonsai Be Smaller?

If you think your bonsai is already too big, you can try and go smaller. This is actually quite difficult, but not impossible.

Obviously a bonsai tree is going to keep growing, so over time, it will always get larger. You can’t escape this. Likewise, you can’t just reverse this and make a tree shrink.

However, you can cut trees back, or reduce them significantly in various ways, although this will not reduce everything.

For example, if you trunk is 3 inches across, it’s always going to be this thick, but you can reduce the height of the trunk which can make it look smaller. You can also develop smaller leaves and branches which again will make it look smaller.   

Over time you can reduce a larger tree into something a lot smaller and compact.

The General Ratio Will Tell You What Size A Bonsai Should Be

Regardless of whether you make your bonsai tree larger are smaller, the one thing that will make it look good is the general ratio of all the separate parts. If everything is in proportion, you will have a good tree. If something is off, it will affect the look of your tree.

If you look at trees in nature you will see they naturally have an excellent balance of ratios throughout the tree

I would say my biggest issue with my bonsai trees is my trunk thickness. I have a lot of skinny trunks and then some excellent branch size and leaf size. However, the lack of thickness in the trunk just makes the tree not look quite right. These trees look like little bushes or maybe young trees at best. They are not convincing as miniature versions of full size trees just yet.

You will often see this issue with leaf size, or branch size. All aspects of the bonsai tree may look great, but then the leaves are just way too big, or the branches are just too long. If this happens the tree just doesn’t look quite right as a bonsai. The ratios are not balanced and in proportion with each other.

The best way to know if your bonsai trees are in proportion, is to either to try and measure them with maths, or just look at them to tell if they have a good general ratio,

Using Maths To Work Out What Size A Bonsai Should Be

You may often see the “golden ratio of bonsai” that you need to follow in order to make you bonsai trees look good.

It’s described as being the height of your tree should be about 6-12 times of the width of your trunk.

So, if you have a 1 inch trunk, you need your tree is anywhere between 6-12 inches tall. if you do this, it’s going to look about right.  

Or you can look at it the other way, if you want a 12 inch tall tree; you need your trunk to be about an inch thick.

There is absolutely nothing wrong with this ratio. If you stick to it, you will probably end up with a nicely proportioned trunk height and thickness.

My only issue is that I’m not going to get my tape measure and calculator out to start evaluating my bonsai trees.

Also this ratio is only good for your trunk size. You can have the perfect trunk thickness for your 12 tall inch tree, but if the leaves are massive, and like the size of your hand, it’s still not going to look right. The trunk is going to look all out of proportion and too small compared to the massive leaves. The ratio isn’t going to be right.

Using Your Eye View To Work Out What Size A Bonsai Should Be

This is the method I like to use. I just look at my bonsai trees and evaluate them to see if they are in proportion and if the ratios look good.

I think this is obviously a little more subjective and you can often lie to yourself about how good a bonsai tree is, but if you try and take a step back and look at the tree honestly, you can usually evaluate it quite well.

Taking picture of your bonsai is also a great way to help take a step back and study the tree from a different perspective.

You just then need to ask yourself if the different aspects of the tree look right.

Is the tree height okay? What about the thickness of the trunk? Then you can move on to ask yourself if the branches are in scale and if the leaves are the right size. Basically does your bonsai look like a full size tree in miniature and if it doesn’t, what needs to change and how can you do that?

If you look at your bonsai trees like this, you will easily work out what needs developed and what areas are doing really well.

Measuring with a tape measure is just a little too much for me. Each tree is unique and individual. I think it is better to evaluate each bonsai tree by itself. Then you can take into account its style and any flaws or any growth habits that can affect its proportions negatively, or positively and then decide if the tree looks like it is in proportion of not.


A bonsai can be any size. So long as it has the right proportions you can’t really go wrong.

Focus on keeping your tree healthy and then you can work with the healthy growth to style it and shape it in a way that will keep it miniature enough to make it look like a smaller version of a full size tree.