How Much Filament Do You Need For 3D Printing?

Filaments for 3D Printing

When I bought my first 3D printer, it came with a small spool of PLA filament. This very quickly ran out, and left me wondering how much I needed to buy.

How much filament do you need? You should always have 2 spools on hand at all times. With 2 spools, there is a backup for when the other runs out.

I only had one spool when I started, and regretted not getting another. If I had known how to limit my filament usage, it would not have run out as quickly. Fortunately, it’s easy enough to determine how much filament you’ll be using.

Why Two Spools?

As a beginner 3D printing hobbyist, you’re gonna make a lot of mistakes. As a seasoned hobbyist, you’re still gonna make mistakes.

Failed prints are just a part of 3D printing. Everyone I know who owns a 3D printer has an entire bin full of messed up prints.

A lot of times the printer just needs to be re-calibrated, but most of the time its user error. I spent nearly an entire roll of filament trying to perfect my first models.

Many failed prints and annoying mistakes later, my first roll of filament was completely gone. And the worst part: it ran out in the middle of a large print. The entire print was ruined, and I had to go online and order another filament.

It is always important that you have at least 2 rolls of filament on hand at all times. When one runs out, order another and start using your backup spool.

The filament that your 3D printer comes with (if it comes with any at all) will be smaller than the average roll. Even then, you may not want to use it much, as the quality generally isn’t great.

The off-white filament I had looked terrible compared to the brilliant white one I bought. When I started purchasing many other awesome colors, I fell in love with trying new filaments.

For your first two rolls, I recommend getting first a white filament to experiment with, and then whatever color you want. Whether it’s electric green or hot pink, it’s gonna make your prints look great!

By buying a white filament, your can sand and spray paint it all you want. If you buy a fun color, you probably won’t want to cover up its beauty with paint.

I also recommend trying several different brands of filament, as every filament brand has different qualities. For example, some are stringier than others, and some are more brittle.

Recently I purchased a brand that requires a very high melting point, which in turn caused a lot of stringing on the surface, but also gave it a shinier finish.

Be wary of purchasing cheap or off brand filaments, as they have the potential to clog your extruder, and may even ruin it. Any filament from a well-known company will print great though.

You may start with only 2 filaments now, but inevitably you’ll end up with a cabinet full of them like I have. Just get to know the ones you have now, and figure out which brands you like the best.

How to Measure your Filament

It’s actually pretty easy to avoid running out of filament during a print. All you have to do is calculate the amount that is left on the spool.

Before you can do that, there are a few things you need to know about filament measurement.

Typically 3D printer filament comes in 1kg spools. It is possible to get larger than that, but companies don’t sell them as readily.

No two filaments weigh the same. There are different densities for different materials, varying spool weights, and different filament weights. Sometimes, the roll will have its spool weight written on it.

When its not written on the side, the easiest option is to google the spool weight from the manufacturer. Often times you’ll find a chart someone made showing all the spool weights for various brands.

Once you have the spool weight, weigh your used filament roll on a scale to see how much it weighs (in grams). Once you have that number, you are ready for the simple formula:

Weighed Roll – Spool Weight = Remaining Filament Weight

Using this number, you can look in your slicer and see if you have enough left on the roll. If not, there are several ways to reduce the amount of filament you’ll use

How to Lower Your Filament Usage

Every single 3D print has a different amount of filament used. To find the amount per print, simply place your file in your slicer and prepare it to print. There are many factors that contribute to how much is used, but here are the main ones.


Obviously, the larger you make a model the more filament will be used. If you find that the model just uses way too much filament, consider scaling it down 25-50%.

Doing this will decrease your filament usage by a lot. Even just a minor decrease of 5-10% can have a big impact both on filament amount and print time.


Here is where things get more complicated. Infill is what gives weight and structure to your print. Of course it is possible to print things without infill (like vases), but most files require it.

In order to limit your filament use, turn your infill percentage down in your slicer. Generally, 8-15% is good enough, providing it doesn’t need any structural integrity.

Some people prefer to turn it way up to make it a heavier model. If that’s the feel you want then go for it! Just make sure you have enough filament, because higher infill will dramatically increase your filament use.


Supports are unavoidable for some prints. The best thing you can do is to orient your model to use as little supports as possible. Sometimes this involves digitally cutting your model into pieces before printing.

Different slicers have different support structures, meaning different filament amounts. You’ll have to use different slicers to see which one you prefer.


Some pesky models just don’t seem to stay stuck while printing. If this happens, you might need to print with a raft.

A raft is a thick layer under your part that adheres extremely well to the bed. Using one of these will drastically improve your print’s chance of succeeding, but at the cost of a little extra filament.

Sometimes, a raft will be the difference between a success or a massive failure. It would be awful for a 50 hour print to fall off 45 hours in.

How to Make your Prints Fail Less

Failed prints is probably one of the worst filament wasters there is, but there are a few ways you can avoid them.

First, always verify your settings are correct before printing. Forgetting to turn supports on could result in a huge amount of wasted filament. Having the wrong temperature could make your filament extrude improperly.

Secondly, closely watch your print during the first few layers. Most of the time, you can tell whether or not a print will fail just by looking at the initial layers.

Does the print look under-extruded? Is it properly adhered to the bed? Is filament flowing evenly? Answers to these questions can be determined only a minute or two after starting it.

Even if you watch the first layers print, that doesn’t mean it still won’t fail. Periodically check up on it to see the progress. It can also be quite satisfying to watch the individual layers print (I know, I’m weird).

If anything looks wrong, that’s because it probably is. If you have doubts about it succeeding, stop the print immediately and find a fix. It’s not worth losing hours of printing because you hoped it would sort itself out.

How To Keep Filament from Drying Out

If your filament is exposed to the open air for too long, it will become very brittle. If this happens, it will often snap during a print, causing the print to be ruined.

It could also cause your print to crack or have holes in it, as excess moisture can creep into the exposed plastic.

What can be done about this? The easiest solution is to store it in an airtight bin or cabinet. Filament rolls often come with packs of silica gel, which you can throw in there to help absorb moisture.

I have seen people telling others to go as far as creating a vacuum sealed box for storing them. This is extremely overkill, as you would never need to go through that amount of effort. Just a simple bin will suffice.

Whenever your are finished printing, simply take the filament out of the printer and put it into storage. If you switch colors, just make sure you push the old filament through the nozzle before printing (unless you want some interesting color blending).

Jay Simmons

Jay Simmons is the main writer for The 3D Bros. He has several years experience working with 3D printers, and is the the co-owner of Cubold Manufacturing, LLC.

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