What is a purge tower?

A purge tower (or wipe tower) is a small block printed alongside your model during colour changes. It purges the old colour from the nozzle before printing the new colour, ensuring clean transitions.

How much filament does a purge tower use?

Each colour change typically purges 1-5 cm³ of filament depending on your slicer settings. With many colour changes this can add up to significant waste — sometimes 30-50% of the total filament used.

How can I reduce purge waste?

Reduce waste by minimising colour changes per layer, using a purge bucket instead of a tower, printing purge into infill of another model, or using transition settings in your slicer to reduce purge volume.

What density is used for waste calculation?

The default density is 1.24 g/cm³ which is typical for PLA. PETG is similar at 1.27 g/cm³. Adjust the cost per kg in Advanced Options to match your actual filament.

3DPrintCalcs

Multi-Colour Print Calculator — Filament & Waste

Calculate total filament needed for multi-colour prints including purge tower waste, and compare cost against single-colour printing.

Number of Colours

Number of different yarn colours used

Print Weight Per Colour

Average model weight per colour

Purge Volume Per Change

Purge tower volume per colour change

Total Colour Changes

Total changes across all layers

How We Calculate This

This calculator totals the filament for all colours plus purge tower waste from colour changes.

The formula

Model filament = Colours x Weight per colour

Purge waste = Colour changes x Purge volume x Density

Total = Model filament + Purge waste

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Always verify settings with test prints before committing to final prints.