Work out tolerance stack up instantly with clear inputs, formula shown and shareable results.
Worst case stack-up adds tolerances arithmetically and guarantees every assembly fits, at the cost of very tight part tolerances. Root sum square assumes the individual variations are independent and normally distributed, which is realistic in volume production and typically yields a stack 30-40 percent smaller.
Worst case
Total = t1 + t2 + t3
Statistical
Total = sqrt(t1² + t2² + t3²)
Preliminary estimate only. Tolerance analysis for functional or safety-critical assemblies should be verified by a qualified engineer including process capability data.
Total = t1 + t2 + t3. Worst case stack-up adds tolerances arithmetically and guarantees every assembly fits, at the cost of very tight part tolerances.
For safety-critical interference, single-piece or low-volume builds, or where the processes are not centred and in statistical control. RSS assumes randomness that a biased process does not provide.
This calculator takes 4 inputs: First tolerance, Second tolerance, Third tolerance, Stack-up method. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.