Tolerance Stack-Up Basics for Real Parts
When this applies
Use this guide when nominal dimensions look fine on paper but you need to understand how part variation can still break an assembly in production.
Tool to use
Linear stack-up from nominal dimensions and bilateral tolerances with worst-case and RSS views.
Open Tolerance Stack-Up Calculator →Steps
- 1List the contributors that accumulate in the same assembly direction.
- 2Compute the nominal total and the worst-case min/max envelope.
- 3Compare that with an RSS estimate only if your team accepts a statistical tolerance model.
- 4Check whether the resulting fit still supports the assembly intent.
- 5Escalate to richer tolerancing and inspection logic when geometry or datum structure matters.
Examples
- Checking if multiple part tolerances can eliminate a designed clearance.
- Explaining to manufacturing why a nominally correct assembly can still fail in stack-up.
What to avoid
- Ignoring stack-up because each individual part is within tolerance.
- Using RSS without any agreed capability basis.
- Treating one-dimensional stack-up as a full GD&T replacement.
Related tools
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FAQ
Should I use worst-case or RSS?
Worst-case is the safer first answer. RSS is useful only if your team accepts the statistical assumptions behind it.
Does this replace GD&T?
No. It is a quick stack-up guide for linear assemblies, not a full geometric tolerancing workflow.