Same standard
Both .step and .stp follow ISO 10303 (STEP) for neutral CAD exchange.
Knowledge中文
STEP vs STP: Same Format, Different Extension
In short: .step and .stp are the same thing. Both are ISO 10303 STEP files for CAD data exchange. The shorter .stp extension exists mainly because older Windows versions favored three-letter extensions.
发布时间 2026/06/10最近更新 2026/06/10
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Just the extension
.stp is a legacy short form of .step; the file content is identical.
Opens the same way
Any STEP-capable viewer or CAD tool opens both extensions.
Why two extensions exist
Older Windows systems and some CAD exporters preferred three-character extensions, so .stp became common alongside .step.
Today both are widely accepted and interchangeable; you can usually rename one to the other without issue.
When the extension matters
A few strict pipelines or upload validators only accept one extension. In that case simply rename .step to .stp (or vice versa).
The internal data — geometry, assembly tree, colors — is the same regardless of the extension.
FAQ
Is STP the same as STEP?
Yes. They are the same ISO 10303 STEP format; .stp is just a shortened extension of .step.
Can I rename .stp to .step?
Yes, in almost all cases renaming between the two extensions works because the file content is identical.
How do I open a .step or .stp file?
Use any STEP viewer or CAD application — you can also preview both directly in the browser online.