Tolerance Stack-Up Calculator
Build a one-dimensional dimensional chain and compare worst-case accumulation with an RSS estimate. Use the contribution chart to identify which tolerances dominate the total variation.
Dimension chain
Enter each nominal dimension, its bilateral ± tolerance, and whether it adds to or subtracts from the stack.
Results
Add dimensions and calculate.
Tolerance contribution
Worst-case vs RSS
Worst-case adds the absolute bilateral tolerances, giving a conservative guaranteed range when the contributor limits are valid. RSS uses √Σt² as an estimated statistical stack tolerance and is appropriate only when the chosen statistical assumptions are justified. RSS is not a guaranteed fit limit.
Engineering assumptions
- One-dimensional, linear stack with independent contributors.
- Each contributor is represented by a bilateral ± tolerance.
- Direction affects the nominal stack, but not the absolute worst-case tolerance sum.
- The RSS result is an estimate; its engineering meaning depends on the underlying distributions, centering and independence assumptions.
- Complex GD&T, 2D/3D variation, correlation, datum structure or nonlinear relationships require a dedicated tolerance analysis.
Engineering aid only. Confirm the stack direction, datum scheme, tolerance definition and applicable drawing/design requirements before using the result for production decisions.