Tolerance Stack-Up Calculator
Add a chain of dimensions and tolerances to find worst-case and statistical (RSS) stack-up results.
Using this calculator responsibly
The Tolerance Stack-Up calculator is an engineering aid for checking a shop-floor estimate before a setup, quote, or process review. Enter values in the units shown, confirm material properties against the applicable specification, and keep a record of the assumptions used. Calculator output does not override machine capacity, tooling limits, part requirements, or a qualified engineer's approval.
Before using a result in production, repeat the calculation with the extreme values allowed by the print or process window. Check that the selected material, thickness, geometry, and safety factor reflect the actual job. If a result approaches a press, die, fastener, or machine limit, stop and verify it with the equipment manufacturer or responsible engineer.
Inputs and results
Read every field label before entering data and avoid mixing inch and metric values. A useful result should be traceable to the job number, revision, material certification, and machine or tooling record. Treat warnings, invalid ranges, and unusual outputs as reasons to inspect the inputs rather than as values to work around.
Stack-up adds the tolerances along a dimension chain to predict the final gap or fit. Worst-case sums every tolerance; the statistical RSS method root-sum-squares them for a realistic spread on volume production.
Formula: Worst case = Σ|tolᵢ|; RSS = √(Σ tolᵢ²)
Worked example
- Four parts each ±0.005 in. Worst case = 4 × 0.005 = ±0.020 in.
- RSS = √(4 × 0.005²) = ±0.010 in — half the worst-case spread.