Updated 2026-10-06
To convert IGES to STEP, drop the .iges or .igs file into the converter below and download the .step. The translation is exact: planes, cylinders and NURBS surfaces arrive as the same surfaces, with nothing turned into facets. 2 solid conversions a day need no account. If the sender can export STEP directly from their CAD system, that is the cleaner source.
2 solid-geometry conversions a day with no account. No card, no install.
On our servers. No account: deleted within 24 hours. Signed in: kept until you delete them. Never shared or used for training.
IGES and STEP both store B-rep geometry, so planes, cylinders, cones and NURBS survive and dimensions, radii and tangency are preserved exactly.
IGES and STEP both store exact geometry, so the shape does not move: a hole is one cylindrical face either side, and dimensions, radii and tangency are preserved.
What changes is the container and how it is read. IGES predates STEP and was designed around surfaces, so many IGES files are a set of trimmed surfaces that sit edge to edge without ever having been joined into a solid, sometimes with small gaps between them. STEP can describe a closed solid, and most CAD systems handle it more reliably. The conversion carries the IGES as it is: a closed body stays a closed body, and loose surfaces stay loose surfaces. It does not invent edges that were never there.
The converter checks the IGES on the way in and tells you if it already had invalid faces or open shells, so a defect in the original is not blamed on the conversion. Colours, levels and other IGES attributes are not carried.
IGES predates STEP and is still requested by older CAM systems and mould and die workflows. It stores exact geometry, but many IGES files are loose trimmed surfaces that never close into a watertight solid. Unless someone asks for IGES by name, STEP is the better choice.
A CAM programmer, toolmaker or legacy system asked for IGES, or you were handed one and need something current.
STEP (ISO 10303) is the closest thing engineering has to a universal solid format. It stores exact B-rep geometry — a hole is a cylindrical face, not a ring of facets. Fusion 360, Inventor, Onshape, SOLIDWORKS, Creo, NX, CATIA and FreeCAD all read it; .step and .stp are the same format. AP242 supersedes AP203 and AP214.
What you send when the other side has to keep modelling, quote machining, or open the shape in a different CAD system.
Keep the part open: fill it with a lattice, check it with FEA, texture a surface, or slice it into cut-ready sheets. These workspaces are in early access — create an account, then apply from inside the app.
Going the other way? Convert STEP to IGES.