How to Measure a STEP File Online (Without Installing CAD)
Most browser viewers show a mesh and guess at units. CADDaddy loads STEP/IGES in millimetres, shows bounding-box L×W×H, and lets you measure distance — plus planar face area on Pro.
Why STEP measurement fails in most online tools
STEP stores precise solids. Many web viewers tessellate the geometry, normalize the scene to “fit the screen,” then leave you with unitless numbers. You Slack “120” and nobody knows if that was millimetres or inches.
CADDaddy loads STEP and IGES through OpenCascade (WASM) with an explicit millimetre linear unit, then undoes view normalization when reporting distances. The measure panel labels that trust signal: mm from STEP/IGES.
The 60-second measure workflow
- Open caddaddy.app/dashboard and drop a
.step/.stpfile (works as guest). - Turn on Measure. Read the unit chip and the live BBox L × W × H — overall envelope before you click anything.
- For a critical feature: snap two vertices (distance mode) or click a planar face (face area, Pro).
- Switch display units (mm, cm, m, in, ft) when the file units are known — values convert instead of lying quietly.
Bounding box vs point-to-point vs face area
- BBox L×W×H — fastest “will it fit / which revision” check. Sorted longest to shortest so envelope size is obvious.
- Distance — hole centres, flange width, mating gaps. Vertex snap keeps picks honest.
- Face area (Pro) — planar faces from STEP BREP ranges. Useful for plating, gasket contact, or “is this the large pad?” without opening SolidWorks.
None of this replaces a drawing or CMM for contractual tolerance. It replaces waiting for someone to install CAD just to answer “is this the 120 mm part?”
Free vs Pro for measurement
Viewing, orbit, and the part tree stay free. Measurement has a free taste, then Pro ($19 / ~¥139 one-time) unlocks unlimited measure, section, face area, larger files, and clean review links. Mesh formats (STL/3MF) still need calibration — they do not carry trusted STEP units.
Try it on a real STEP
Drop a STEP and confirm envelope + a feature dimension in under a minute.
Open the STEP viewer →FAQ
Are STEP units always millimetres?
Most mechanical STEP exchange files are millimetres. CADDaddy loads with an explicit millimetre linear unit and surfaces that in the UI. If a file was authored in inches, calibrate once from a known edge.
Can I measure face area on STL?
You can click triangles, but BREP face grouping is a STEP strength. Prefer STEP for area and trusted units; use STL for print meshes.
How do I share measured context with a supplier?
Generate a review link from the dashboard. Recipients open the same model in a browser — no CAD seat required.