Free tool
3D printing tolerance calculator
Enter the size of the shaft, pin or object and your printer's fit gap. You get the hole (or slot) size to model for each kind of fit. Values are on the diameter.
| Fit | Use | Model the hole at |
|---|---|---|
| Press fit | Bearings, dowel pins that must not move | 6.00 – 6.12 mm |
| Snug fit | Knobs on shafts, lids that stay on | 6.12 – 6.18 mm |
| Sliding fit | Sliding lids, drawers, hinges | 6.30 mm |
| Rotating fit | Axles, hinge pins that turn | 6.30 – 6.39 mm |
| Loose / drop-in | Holders, cradles, cases | 6.54 – 6.90 mm |
Screw clearance holes with your fit gap
| Screw | ISO clearance | Printed hole |
|---|---|---|
| M2 | 2.40 mm | 2.55 mm |
| M2.5 | 2.90 mm | 3.05 mm |
| M3 | 3.40 mm | 3.55 mm |
| M4 | 4.50 mm | 4.65 mm |
| M5 | 5.50 mm | 5.65 mm |
| M6 | 6.60 mm | 6.75 mm |
| M8 | 9.00 mm | 9.15 mm |
How the calculator works
The fit gap is the extra diameter at which a printed pin just slides into a printed hole on your printer. Tighter fits use a fraction of it, looser fits a multiple. These factors are practical starting values for FDM printing; always print a small test of the critical feature before a long print. Read the full tolerance guide and the screw hole size guide.
Don't want to calculate at all?
FitPrint applies your fit gap to every hole, slot and cradle automatically when it designs a part for you.
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