Thread Fit Calculator for 3D Printing
Get practical CAD offsets for printed male/female threads so bolts and nuts assemble reliably.
Male / female CAD
5.820 / 5.320 mm
Enter your slicer value if already applied globally.
Recommended fit
- Diametral clearance0.200 mm
- Radial clearance0.100 mm
CAD thread dimensions
- Male thread major dia (CAD)5.820 mm
- Female thread minor dia (CAD)5.320 mm
- Female thread major dia (CAD)6.040 mm
Internal minor is based on nominal tap-drill (5.000 mm) plus print compensation.
Offset summary
- External thread offset-0.180 mm
- Internal minor offset+0.320 mm
- Layer adjustment+0.000 mm
- Size adjustment+0.000 mm
Metric thread quick reference
| Thread | Major dia (mm) | Pitch (mm) | Nominal internal minor (mm) |
|---|---|---|---|
| M3 | 3.00 | 0.50 | 2.50 |
| M4 | 4.00 | 0.70 | 3.30 |
| M5 | 5.00 | 0.80 | 4.20 |
| M6 | 6.00 | 1.00 | 5.00 |
| M8 | 8.00 | 1.25 | 6.75 |
| M10 | 10.00 | 1.50 | 8.50 |
Practical workflow for reliable threads
Use these dimensions as your baseline, then print a short test coupon with three variants at -0.05mm, baseline, and +0.05mm on internal minor diameter. Lock the winning value per material and printer.
FAQ
Why do printed threads bind even when modeled to standard dimensions?
FDM threads are sensitive to extrusion width, layer stepping, and slicer compensation. Male features often print oversized and female roots close up, so nominal CAD dimensions rarely fit perfectly without offsets.
Should I tune in CAD or with slicer horizontal expansion?
For repeatable production, tune in CAD and keep slicer expansion near zero. Use slicer expansion only for quick one-off adjustments across a whole model.
Do horizontal threads need extra clearance?
Usually yes. Horizontal thread axes often need more clearance due to stair-stepping and support/contact artifacts, especially on coarse layers.
How do I finalize fit quickly?
Print a short thread test coupon with 3 variants around the recommended values in +/-0.05mm steps. Lock the winner as a material+printer design preset.
Related tools & guides
Tolerance & Clearance Calculator
General moving-part fit guidance beyond threads.
Shrinkage Compensation Calculator
Adjust dimensions for ABS, Nylon, and other shrink-prone materials.
Nozzle Wear Calculator
Track wear that can throw off threaded part accuracy.
Free 3D Print Cost Calculator
Estimate final print cost including electricity and margin.
How to use the thread fit calculator for 3D printing
Select your metric thread size, fit class, material, and printer profile. The calculator outputs the exact outer and inner diameters and recommended offsets for both male and female threads — compensating for the dimensional error that FDM printing introduces — so your printed threads actually assemble correctly.
Why do 3D printed threads not fit standard nuts and bolts?
FDM printing adds material slightly outside the nominal diameter due to extrusion width, elephant foot, and layer lines. A printed M6 thread at nominal size will typically be 0.1–0.3 mm oversize on the outer diameter. The thread fit calculator compensates by applying material-specific and printer-specific offsets so the final printed thread assembles correctly.
What is the best filament for 3D printed threads?
PLA has the least shrinkage and is easiest to calibrate for threads. PETG is slightly flexible and better for threads that need to flex or seal. Nylon threads are self-lubricating and excellent for load-bearing applications. Avoid TPU for structural threads — its flexibility makes dimensional control very difficult.
How tight should a 3D printed thread fit?
For hand assembly with no tools, use "easy assembly" offset (+0.08 mm on hole diameter). For standard assembly with tools, use "standard fit" with no extra offset beyond material compensation. For press-fit or interference-fit threads, use "tight fit" (−0.05 mm). The correct fit class depends on your assembly method and load requirements.