3D printing · Multicolor
Multicolor 3D print purge waste calculator.
Enter the number of filament changes from your slicer and the flush per change, and the calculator returns the grams you will throw away, what that costs and how it compares with the part itself. Example from Bambu Lab’s own wiki: a four-colour cube with 153 filament changes wasted 83 g to make an 11 g object, 7.5 times the part’s weight. Printing nine of them on one plate keeps the same 83 g, which is 9.2 g per cube.
Your numbers
Result
Working out the result.
How the waste is calculated
Every time the printer swaps filament it pushes the old colour out of the nozzle before printing the new one. Bambu Lab’s wiki page “Reduce wasting during filament change” (read 26 October 2026) calls this flushing, or purging, and says the volume depends on the pair of colours: “Darker colors need a higher volume flush to switch to lighter colors, and lighter colors need less to switch to darker colors.” After the flush the nozzle usually prints into a prime tower. The same page says the total wasted filament is “directly tied to the total Filament Change Times” and that the flush volumes can be scaled with the Multiplier field, where 1.00 is the default and 0.90 is 10% less for every pair.
This calculator multiplies the number of changes by the flush per change and by the multiplier, then adds the prime tower: waste = changes × flush per change × multiplier + prime tower. It does not know your colour pairs, so the flush per change is an average you supply: the slicer’s waste total divided by its change count is a good one. For the layer-height comparison it scales the change count by the ratio of layer heights, because the wiki shows changes falling with fewer layers. That ratio is our approximation, not a published formula, and the result says so.
Worked examples with real numbers
- The wiki cube at 0.2 mm. 153 filament changes, 83 g wasted, an 11 g object: 0.54 g per change and 7.5 times the object’s weight.
- Nine cubes on one plate. The wiki says changes and waste stay the same, so waste is still 83 g against 99 g of parts, 9.2 g per cube and 0.84 times the parts’ weight, and you get eight extra cubes for no extra waste.
- The same cube at 0.28 mm. The wiki measured 111 changes and 61 g. Scaling 153 changes by 0.2 ÷ 0.28 gives 109, and 109 × 0.54 g is 59 g, within 2 g of the measured figure.
- Prime tower orientation. The wiki shows a tower of 14.76 g for a part with colour changes at the top and 9.05 g with the same part turned upside down so changes are near the bed, about 40% less.
- A multiplier of 0.90 (illustrative). Suppose 100 changes at 0.4 g and the 14.76 g tower: 40 + 14.76 = 54.76 g at 1.00. At 0.90 the flush is 36 g, the total 50.76 g and the saving 4 g. The wiki warns to run a test print, because a multiplier that is too low shows as discoloured layers.
Ways to cut purge waste, from the same page
Put more copies on the plate so one set of changes serves several parts. Raise the layer height so there are fewer layers and fewer changes. Turn the part so the colour changes sit low and the tower stops early. Use “flush into objects’ infill” or “flush into this object” so purged filament becomes hidden infill or a throwaway object. In the wiki’s cube example, flushing into other objects cut about 70 g of flush to less than a gram.
What this calculator leaves out
It does not read the colour table, so it cannot say which pair is expensive. It does not model the filament wiper, tool-changer hardware or a printer that purges differently. The slicer’s own preview is the authority for your file; this tool is for planning, comparing and pricing.
Common mix-ups
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Often assumedMore copies on the plate means more purge waste.
What the source saysIn the wiki’s four-colour cube example, duplicating the cube to nine copies left the filament changes and the waste unchanged at 153 changes and 83 g, and produced eight additional finished cubes. [1]
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Often assumedThe prime tower is a fixed size.
What the source saysThe tower must reach the highest layer with a colour change. Turning the same part upside down so the changes were at the bottom cut the tower from 14.76 g to 9.05 g, about 40% less. [1]
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Often assumedWaste depends only on how many colours you use.
What the source saysIt is tied to the number of filament changes, and that falls with fewer layers. Raising the layer height from 0.2 mm to 0.28 mm cut changes from 153 to 111 (27% fewer) and waste from 83 g to 61 g (26% fewer). [1]
Checked against these sources on .
Frequently asked questions
How much filament does a colour change waste?
It depends on the colour pair and the slicer, so there is no single figure. In Bambu Lab's wiki example, 153 changes and the prime tower produced 83 g of waste, about 0.54 g per change on average. Darker to lighter changes need a larger flush than lighter to darker ones.
What is the flush multiplier?
A setting in Bambu Studio that scales every flush volume. 1.00 is the default and 0.90 is 10% less flushing for every colour pair. The wiki suggests 0.8 or 0.9 as a quick way to save filament but warns to run test prints, because too low a value shows as discoloured layers.
Does this work for printers other than Bambu Lab?
The arithmetic does: waste is changes times flush plus tower, whatever the slicer. The multiplier and the example figures come from Bambu Studio, so enter your own slicer's change count and waste if you use another system.
Why is the waste larger than the part?
Each change flushes the nozzle whatever the size of the part. In the wiki example 83 g of waste made an 11 g cube. Putting more copies on the plate spreads the same waste over more parts.
How do I find my flush per change?
Divide the slicer's waste total by its number of filament changes. Or read a flush volume in mm3 from the flushing volumes table, switch the unit to mm3 and enter your filament density.
Is the layer-height comparison exact?
No. It scales the change count by the ratio of layer heights. Applied to the wiki cube it predicts 109 changes where the slicer counted 111, so treat it as a planning estimate.
Sources
Retrieved
- Bambu Lab Wiki: Reduce wasting during filament change — flushing volume, multiplier, prime tower, flush into infill and objects, the 153-change and 83 g cube, nine copies, layer height example (read 2026-10-26)
- PLA technical data sheet (Harvard 3D printing) — solid density 1.24 g/cc, ASTM D792, used as the default density (read 2026-10-26)
An estimate for planning, not your slicer’s number
Not affiliated with Bambu Lab. The wiki figures were read on 26 October 2026 and describe one example print; yours will differ. Nothing you type is sent or stored.