Engineering tool · V0.2

3D Printing Clearance Calculator

Get a conservative starting clearance and calculate a mating feature size. The result is a test starting point, not a universal printer tolerance.

Process

Application

Reference feature size (mm)For example, a 10 mm shaft or tab.

Geometry

Starting clearance—

Suggested mating size—

Clearance basis—

ValidationPrint a coupon

Use these values as an initial test only.

Printer calibration, material, orientation, nozzle or laser spot, layer height, feature size and post-processing can shift the fit significantly. Calibrate with a small tolerance coupon before committing to production geometry.

Reference basis used in this V0.2 tool

For FDM, the tool uses a conservative 0.3 mm starting gap for movable parts, consistent with Prusa’s guidance that there is no universal tolerance and that at least 0.3 mm is a useful initial value for movable parts. UltiMaker recommends 0.6 mm between parts printed together when they must move after printing.

For Formlabs SLA, the current Form 4 design guide recommends 0.4 mm minimum clearance. For Formlabs Fuse SLS, the design guide lists 0.2 mm minimum assembly tolerance and 0.3 mm integrated-assembly clearance for smaller features, increasing to 0.4 mm and 0.6 mm for larger features. This calculator intentionally uses the larger-feature values as conservative defaults.

The calculator intentionally rounds these into conservative process/application starting values rather than presenting them as guaranteed fits.