In this answer user Barafu says,

Yet I manage to keep my tolerances +- 0.05 mm which is enough for everything but miniature printing.

I have asked for clarification on that answer regarding what is meant by "miniature printing" but in the meantime, I want to ask the general question.

What impact does dimensional accuracy of filament have on final print quality, and why? Does it vary between different filament types?


2 Answers 2


Dimensional accuracy is not as important as dimensional uniformity. I can print with undersized (or oversized) filament, adjusting the flow appropriately, provided the filament has a consistent diameter. When creating filament in-house, without expensive equipment, it is difficult to maintain the same diameter throughout the entire extrusion. It is likely this extrusion diameter (when creating filament, rather than the output of the actual print head) to which Barafu is referring when he mentions his tolerances: +/- 0.05 mm in diameter. Which is reasonable.

The "miniature printing" comment likely refers to printing miniature models for tabletop gaming.

If the source filament becomes wider than expected, the output will have overflow, or more material than desired will be deposited, and this will certainly affect the quality of the piece.

  • $\begingroup$ Perhaps I should adjust the question, then? I see most PLA filaments advertised as 1.75 mm (+/-0.05 mm). Does this mean a variance of 0.05 mm in the diameter throughout the filament? Or that the diameter is uniform, and it's within 0.05 mm of the advertised diameter? $\endgroup$ Jan 26, 2017 at 18:12
  • $\begingroup$ It could mean either, but most likely the first option. Your print head is likely tuned to accept a certain (small) range of filament diameters. $\endgroup$
    – Davo
    Jan 26, 2017 at 18:37
  • 2
    $\begingroup$ @LegendaryDude - it means the first of the two (variance throughout the filament). That number does not give you a degree of certainty but a degree of uncertainty. The cases where the filament may be constantly +0.05 mm or -0.05 mm from its nominal value are just "special cases" of the more general one. $\endgroup$
    – mac
    Dec 20, 2017 at 2:33

Put it simply: they say 1.75 mm with a ± error of 0.05 mm. Which means your flow may vary ±2.9 % while you are printing creating blobs and such.

The smaller the filament tolerance, the more expensive the production costs.

  • $\begingroup$ I'm curious how you arrived at 2.9% when I calculate +-5.7%. The difference in surface area between maximum and minimum allowable diameter is 2.54 - 2.27 = 0.27mm^2. Which is 11.4% maximum variance in extrusion volume or ~+-5.7% from nominal. Have I done something wrong? This is why I buy +-0.03 or +-0.02 filament. They have 6.9% & 4.6% max variance respectively. If I've done something wrong I may be paying more for less benefit than I think. $\endgroup$
    – bielawski
    Jun 7, 2021 at 16:31

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