What is diameter tolerance?
Short answer
Diameter tolerance is how far the filament's thickness can vary from its stated size, such as 1.75 mm. A tolerance of ± 0.02 mm means every part of the spool should measure between 1.73 and 1.77 mm. The tighter the tolerance, the more evenly the filament extrudes.
Guide
Why it matters
Your printer pushes a set length of filament for each move, assuming it's exactly 1.75 mm. Thicker sections push out too much plastic, causing blobs and rough walls; thinner sections push too little, causing gaps and weak layers. Very thick spots can even jam in the extruder or a multi-material system.
What's a good tolerance?
- ± 0.02 mm is excellent, and common for good-quality filament.
- ± 0.03 mm is good.
- ± 0.05 mm is acceptable, but you may see more variation within and between spools.
Diameter tolerance questions
What does ±0.02 mm mean on filament?
That the diameter stays within 0.02 mm either side of its stated size: 1.73 to 1.77 mm for 1.75 mm filament.
How do I measure filament diameter?
With digital calipers, at several points along a metre or two of filament, turning it between readings to catch any ovality.
Does diameter tolerance matter for multi-material systems?
Yes. Oversized or uneven filament is more likely to jam in feeders and tubes, so a tight tolerance helps.
Should I set the measured diameter in my slicer?
If a spool is consistently off, for example always 1.72 mm, setting the measured value gives more accurate extrusion.