Filament Calculator
Turn a slicer’s print weight into filament length, material cost and the share of a spool used, for PLA, PETG, ABS and more. Calculates in your browser.
Material cost
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Show the math
Weight and density give the volume of plastic, and the filament's cross-section turns that into a length:
volume = grams ÷ density · length = volume ÷ (π × (Ø ÷ 2)²)
Cost is the spool price prorated by the fraction of the spool you used:
cost = spool price × grams ÷ spool grams
This covers filament only. Real print cost also includes electricity, machine wear, failed prints and your time, add a margin if you sell prints.
What this does
A filament calculator turns a slicer print weight into filament length, material cost, and the share of a spool used, for PLA, PETG, ABS, and more.
How to use it
- Enter the print weight from your slicer.
- Pick the material.
- Enter the spool price and weight.
- Read the length, cost, and spool used.
How it works
Cost is prorated by the fraction of spool used: spool price × grams ÷ spool grams. This covers filament only, not power, wear, or failed prints.
length = weight ÷ density ÷ cross-section area
Understanding your result
This covers filament only, so it understates the true job cost, which also includes electricity, machine wear, and the filament lost to failed prints and purges. Use the spool fraction to judge whether you have enough left to finish, and remember a near-empty spool is a common cause of a failed long print, so start big jobs on a fuller roll.
Example
A 50 g PLA print is about 16.5 metres of 1.75 mm filament.
Sources & methodology
Last updated .
Frequently asked questions
How is length found from weight?
Weight divided by the material density gives the plastic volume; dividing by the filament’s cross-section area (from its diameter) gives the length.
How is cost calculated?
We prorate the spool price by the fraction of the spool you used: spool price × grams ÷ spool grams.
Does this include all print costs?
No, it covers filament only. Real cost also includes electricity, machine wear, failed prints and your time, so add a margin if you sell prints.
Do you store my data?
No. Everything is computed locally in your browser.
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