How does SimplyPrint track filament usage?

SimplyPrint automatically tracks how much filament each print uses - but only when the file is sent through the platform. This article explains how the tracking works, when usage is deducted, and how accurate you can expect it to be.

How it works: Gcode analysis

When you upload a file to SimplyPrint or slice it using our built-in slicer, we perform a Gcode Analysis. This analysis reads through the sliced file and extracts the total amount of filament that will be extruded - measured in millimeters.

Printers work in millimeters, not grams. The Gcode tells the printer "extrude 150mm of filament" - it doesn't know or care about weight. So SimplyPrint converts that length into grams using two values from your spool's settings:

• Filament diameter - Usually 1.75mm, or 2.85mm for some printers
• Material density - How heavy the material is per unit volume (different for PLA, PETG, ABS, etc.)

When you select a brand preset from the Open Filament Database, the density is already set accurately. If you add custom filament, the density defaults to a reasonable value for the material type - so you generally don't need to worry about it.

See: All about the Gcode Analysis feature

When is usage deducted?

SimplyPrint deducts filament usage when the print ends - whether it finishes successfully, fails, or is cancelled. Usage is not deducted in real-time during the print.

This means:

• During a print - The spool's remaining amount stays at its pre-print value
• After the print ends - The estimated usage is subtracted from the spool
• Via the API - While a print is ongoing, the API returns the spool's value from before the print started

Some places in the interface may show a "live" estimated value during printing, but this is a preview - the actual spool record isn't updated until the print completes.

Cancelled and failed prints

If a print is cancelled or fails partway through, SimplyPrint doesn't deduct the full estimated usage. Instead, we calculate based on how far into the print it got.

For example, if a print is cancelled at 50% progress, we deduct 50% of the estimated filament usage. This applies to all extruders on multi-material prints.

This percentage-based calculation gives a reasonable estimate, though it's not perfect - see the accuracy section below.

Why send files through SimplyPrint?

Gcode analysis gives SimplyPrint deep insight into your print files. Filament tracking is just one benefit - the same analysis also provides:

• Gcode preview - See a 3D visualization of the print before starting
• Accurate time estimates - Based on actual toolpath, not rough guesses
• Layer-by-layer information - See details about each layer during printing
• Print cost calculation - Combine filament cost with machine time, energy, and labor
• Richer print history - See exactly what was printed, with thumbnails and stats
• Queue optimization - SimplyPrint can match files to printers based on material requirements

The more SimplyPrint knows about your files, the better the platform works. Sending files through SimplyPrint isn't just about tracking filament - it unlocks the full potential of the platform.

What counts as "sent through SimplyPrint"?

Any of these methods will trigger Gcode analysis and enable filament tracking:

• Upload a file to your SimplyPrint file storage
• Use the built-in slicer to slice and print directly
• Send from an external slicer using one of our integrations
• Use the mobile app to upload or start prints
• API uploads for automated workflows

Using your favorite slicer

You don't have to use SimplyPrint's built-in slicer. We have integrations with popular slicers that let you send files directly to SimplyPrint with one click:

• PrusaSlicer
• OrcaSlicer
• Cura
• Simplify3D
• And more

With these integrations, you keep your familiar slicing workflow while still getting all the benefits of Gcode analysis - including filament tracking.

See all slicer integrations: simplyprint.io/integrations/category/slicer

What about prints started elsewhere?

If you start a print via:

• The printer's built-in screen or controls
• An SD card or USB drive
• Another print management service

SimplyPrint will see that the printer is printing, but won't know what file is being printed or how much filament it uses. The print won't appear in your detailed job history, and no filament will be deducted from your spools.

How accurate is the tracking?

For most prints, the tracking is quite accurate. The Gcode contains precise extrusion amounts, and the mm-to-gram conversion using material density is reliable.

However, a few things can cause small discrepancies:

Purging and priming

Some printers perform extra extrusion that isn't in the Gcode itself - like purge lines, nozzle priming, or filament loading sequences. This extra usage won't be tracked because it's not part of the analyzed file.

Cancelled prints

When a print is cancelled at, say, 50% progress, we deduct 50% of the estimated usage. But the actual extrusion might be slightly different - if the printer was mid-layer or had already extruded more than the percentage suggests, the real usage could vary.

Retraction and oozing

Minor factors like retraction settings, oozing, and stringing can cause tiny differences between estimated and actual usage. These are usually negligible over the life of a spool.

Multi-material and color changes

For prints with filament changes, the tracking accounts for each extruder's usage separately. But manual color changes or purge towers might not be perfectly captured.

Automatic spool weight updates (Bambu Lab)

Some printers can report more accurate filament data back to SimplyPrint. Currently, Bambu Lab printers with their branded spools support automatic weight updates.

When you load a Bambu spool into an AMS (Automatic Material System), the printer reads the NFC tag and estimates the remaining weight. SimplyPrint can sync this value back to your spool record, giving you a more accurate reading than Gcode-based tracking alone.

This feature is configured in Settings > Printers > Material syncing.

See: The Filament Manager feature

Manual adjustments

If tracking gets out of sync - or you print outside of SimplyPrint - you can always manually adjust your spool weights. Open the spool in the Filament Manager and use the Adjust weight feature to update the remaining amount. You can enter a value directly, or weigh the spool and let SimplyPrint calculate the remaining filament.

Summary

SimplyPrint tracks filament usage by analyzing the Gcode for total extrusion (in mm), then converting to grams using your spool's diameter and material density. Usage is deducted when prints end - with partial usage calculated for cancelled or failed prints. The tracking is generally accurate, with minor variations possible from purging, cancellations, and other edge cases. For Bambu Lab printers, automatic weight syncing provides even more accurate tracking.

Updated on: 23/12/2025