Free online STP to IGES converter

Convert STEP CAD models to IGES for legacy CAD, CNC, and inspection software.

Convert STP to IGES online - free

.stp .iges

Drop up to 3 .STP files here or click to browse

Max 10 MB per file · No registration required · max 30 MB total

Need to convert bigger files or more at once? See plans

Want the highest limits and no ads? See plans

Uploading…

Selected files exceed the 30 MB total limit. Please select fewer or smaller files.

Your file is processed instantly and deleted as soon as you download it.

How it works

1/3

Upload your .stp file

Click to browse to select your file you want to convert or simply drag & drop your file into selected area.
2/3

Perform .stp to .iges conversion

After successful file upload, click to convert when you are ready.
3/3

Download converted .iges file

Conversion result is ready to download.

How to convert stp to iges file

September 27, 2026
CAD formats
No ratings yet.

A legacy CAD program, CNC system, inspection application, or supplier portal may accept IGES but reject STEP. Converting the model provides a compatible exchange file, although feature history, assembly relationships, and some metadata may be lost.

What the STP/STEP format is

STP and STEP are filename extensions and common names for files based on the ISO 10303 CAD exchange standard; files normally use .stp or .step. ISO 10303-21 defines the widely used text-based physical file encoding. Mechanical designers, manufacturers, engineers, suppliers, and inspection teams use STEP to exchange models between SolidWorks, CATIA, Siemens NX, Creo, Fusion, Inventor, FreeCAD, and other CAD systems.

Depending on the application protocol and exporter, a STEP file can contain precise solid and surface geometry, assemblies, component names, colors, layers, units, and product structure. It normally does not preserve the source application's editable feature tree, sketches, constraints, or parametric design history.

What the IGES format is

IGES, also called IGS, is an older ANSI data-exchange specification usually stored as .igs or .iges. Legacy CAD, CNC, tooling, inspection, and surface-modeling systems commonly support it.

IGES represents geometry through entities such as curves, wireframes, trimmed surfaces, and some solid forms. Its broad legacy support can make it necessary for older receiving software, but it generally transfers less dependable assembly structure, product metadata, and design intent than STEP. For modern solid-model exchange, STEP is usually the better source and target format unless the receiving system specifically requires IGES.

How to convert STP to IGES

FreeCAD is a suitable desktop option for a one-off conversion and does not require the original CAD application.

Open FreeCAD and choose File → Open.
Select the .stp or .step file and wait for the model tree and 3D view to finish loading.
Inspect the imported model. For a multi-body or assembly file, select the solid, surface body, assembly container, or individual components that must be transferred. Hide construction geometry that should not appear in the result.
Choose File → Export, select an IGES file type, and save the result with an .igs or .iges extension, such as model.igs.
Reopen the exported file in FreeCAD and, preferably, in the recipient's CAD system. Check the overall scale, units, solid validity, holes, curved faces, colors, and component positions.

Most full CAD systems, including SolidWorks, Fusion, Inventor, Creo, CATIA, and Siemens NX, provide equivalent Open/Import and Save As/Export commands. If the original application is available, it may produce better results because its STEP importer and IGES exporter share the same geometry kernel. For a conversion without installing software, 101convert.com can convert the file online for free; use a desktop application instead when the model contains confidential or controlled design data.

Quality and compatibility limits

IGES normally transfers boundary geometry, not editable parametric features. Sketch constraints, feature trees, formulas, design history, and many assembly relationships are not preserved.
A STEP assembly may become separate IGES entities or a flattened collection of geometry. Confirm whether the recipient needs one file, separate component files, or a native assembly structure.
Verify units and scale after import. STEP commonly records units, but older IGES software may apply a default unit or interpret the file incorrectly.
Solid-to-surface conversion can produce gaps, duplicate faces, inverted faces, or non-manifold edges. Run the receiving application's geometry check and healing tools before machining, tooling, or inspection.
Use the exporter’s normal tolerance and accuracy settings unless the receiving system specifies different values. An unnecessarily tight tolerance can enlarge the file and slow import without improving the source model's manufacturing accuracy.
IGES export cannot restore information that was already missing from the STEP file. Preserve the original STEP file as the master when future editing or re-exporting may be required.

STP vs IGES: format comparison

How the STP and IGES formats compare on the properties that matter most for this conversion.

Comparison of the STP and IGES file formats
Property	.STP STEP (Standard for the Exchange of Product model data)	.IGES Initial Graphics Exchange Specification
Dimensions	3D	3D
Geometry	Both	Both
Materials	Limited	—
Plain-text readable	Yes	Yes
Operating system support	Wide	Wide
Typical file size	Medium	Large
Open standard	Yes	Partly open
Introduced	1994	1980
Developer	ISO	IGES/PDES Organization; later maintained through ANSI/ASME standardization

Open STP file Open IGES file

Information about file extensions and file types is provided by File-Extensions.org

Frequently asked questions

Is the STP to IGES converter free?

Yes, converting STP to IGES on 101convert.com is completely free. No registration, email address or installation is required. If you need a higher file size limit or want to convert more files at once, see our plans.

How large can my STP file be?

You can upload STP files up to 500 MB and convert up to 5 files at once in a single batch.

What happens to my uploaded files?

Files are processed automatically and deleted from our servers within a few minutes after conversion. We never view or share your files.

Do I need to install any software to convert STP to IGES?

No. The STP to IGES conversion runs entirely online in your browser and works on Windows, Mac, Linux, Android and iPhone.

Did the conversion fail?

In most cases, the cause is an incorrect file format. Please upload a valid STP file for this STP to IGES conversion. Occasionally, the issue may be on our side. We analyze recurring conversion failures and disable or fix the converter if we detect a defect.

Will STEP to IGES conversion preserve my 3D model geometry?

It usually preserves the main shapes, but some solid and assembly information may be represented as individual IGES surfaces or curves. Parametric feature history, sketches, constraints, and other native CAD editing data are not preserved.

Will my STEP assembly stay as an assembly in IGES?

Not necessarily; assembly structure, part relationships, names, colors, and metadata may be flattened or interpreted differently by the receiving CAD system. Check the converted file in the target software if separate components matter.

Why does my IGES model import as separate surfaces instead of a solid?

IGES commonly represents CAD geometry as surfaces, and small gaps or imperfect trimmed-face boundaries can prevent the target program from sewing them into a solid. This is especially likely when the source contains complex faces, tiny features, or geometry near its tolerance limits.

Can I convert STEP to IGES without changing the units or accuracy?

Units and geometric accuracy depend on the conversion settings and how the target software interprets the IGES file. Verify the unit system, model scale, tolerances, and critical dimensions after conversion because IGES does not always carry STEP's richer model information.

stp to iff stp to igs

Additional formats for
stp file conversion

Reverse conversion

iges to stp

Convert to iges from
other formats

Share on social media:

Find a converter

Free online STP to IGES converter