Starting a new printing project can be rewarding and yet challenging at the same time. It is rewarding to see your print go from a 3D concept on a screen to a finished product you can touch.
It is challenging because there are several steps you need to go through to get there, and several things could go wrong before you do.
One way in which a project can go wrong is running out of filament right in the middle of a print. While this is not the worst thing that could happen, it is still something you don’t want to run into. So how do you work out how much filament you have left so you can avoid this happening?
There are several ways, some simple and some requiring a little calculation. The simplest is if the spool has filament lengths printed on the side. Some manufacturers produce their filament spools with this convenient feature. Check the sides of the spool to see if it has these measures.
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Another way would be to unroll the filament and measure it. While this basic method works for a short roll, it is impractical for long rolls. Unrolling a long roll of filament can easily lead to a tangled mess of filament.
Also, we recommend that you check out our post How Much Filament Is on A Roll? How Much Is Left on The Spool!

Tracking with NFC tags
Some filament spools have NFC tags that work like barcodes. They allow you to use the built-in usage tracking that certain 3D printers have. Provided the tags and printers are compatible, they will track how much filament has been used and how much is left in the spool. Source
However, the most used method to calculate how much filament is left on a spool is by weight. Filament spool size is given as a weight. Some manufacturers will also give a corresponding length. The amount of filament left can thus be determined by subtracting the weight of the used spool from its original weight.
Here’s how this works in practice.
Tracking filament use by weight
Here you would need to know the weight of the empty spool which is typically given by the manufacturer. The industry average is between 235 to 260g. Then you have the weight of the full spool which you would already know.
As you use your filament, you can weigh it and subtract that from the full weight to find out how much you have used or how much remains.
Generally, it is a good practice to mark how much filament a spool has right after you’re done with a print. In this way, when you start a new project, you know beforehand how much filament you have got to work with.
Tracking with filament runout sensors
Runout sensors are for detecting when your filament has run out during printing. They’re more useful for preventing a ruined print caused by filament running out while in the middle of a print.
A runout sensor can be configured to give you a warning when the filament reaches a certain level. Source
For more on this, we highly recommend that you check out our post ” What Happens When Filament Runs Out? How To Save Your Print!
3D printing is an exciting challenge. It can also be frustrating if you find yourself running out or running low on filament at the wrong time. Fortunately, there are a couple of measures you can take to prevent this from happening.
One of them is knowing how much filament you will need for a print. But how do you work this out?
How Do You Know If You Have Enough Filament?
The main factor that will determine how much filament is required for a print is the specifications of the print or project. The size of the print will inform whether there is enough filament for the project. Slicing software will also give an estimate of how much filament is needed.
Projects vary in terms of:
- The complexity of the print. Some prints may be simpler and require fewer or more layers than others.
- The level of detail needed. If no or little detail is required, you can reasonably expect to use less filament compared to a print that requires fine details.
- The size of the print. It goes without saying that the bigger the print the more filament you will use.
A rule of thumb sometimes used is you need at least one meter of filament per 100 grams of object printed.
Slicing software
Slicing software takes a 3D model which it then “slices” into layers. This information is then sent as commands to a 3D printer where the final print is made. The main function of slicing software is to give the printer readable instructions for printing a 3D model. Source
Depending on the software program, it also gives an estimate of how much filament the print will use. If you know how much filament you have, you will also know, thanks to your slicing software whether it will be enough for your project.
One simple way for making sure you have enough filament for a project is to have two filament spools for each color you may be working with. This is the surest way to guarantee you never run out of filament in the middle of a print.
How Long Will 1KG Filament Last?
How long a 1KG spool of filament will last depends on the size, complexity, and number of prints done. The fewer prints, or the less complex or smaller the prints, the longer the filament will last. Generally, a 1KG filament will print out around 990 grams of an object. This can last a month or several months.
Most filament spools come in 1KG or 3KG weights. Although you can get them for smaller 1KG is the standard weight. The main variable in determining how long it will last is what and how often you print.
If you’re printing often or if you’re printing large or complex prints, naturally your 1KG filament will last a shorter time than someone printing less frequently or less complicated prints.
How Long Does 500g Of Filament Last?
A 500g filament will print up to 490 grams. How long it lasts depends on the usage and the type of prints it is used for. More complicated prints will deplete it quicker. 500 grams can be used over a week or up to 12 weeks depending on usage.
You can extend or make your filament last longer by reducing waste. One simple but very effective way to do this is to store your filament properly. Not storing your filament in airtight containers can easily ruin an entire spool of filament.