Tolerance Stack Up Calculator Patched May 2026

Include nominal dimensions, upper tolerance, and lower tolerance.

Pick one critical gap in your current assembly. Build the Excel sheet above. Compare worst-case vs RSS. You’ll be surprised how often your initial tolerances are either too tight (expensive) or too loose (non-functional). tolerance stack up calculator

| Method | Formula (for additive tolerances) | Best for | |--------|----------------------------------|-----------| | | (T_total = \sum \vert T_i \vert) | Safety-critical, low volume | | Root Sum Square (RSS) | (T_total = \sqrt\sum T_i^2) | High-volume manufacturing (Cpk≥1.0) | Rule of thumb: Use RSS when you have 4+ parts in the stack and assume normal distribution. Use worst-case when human life or mandatory clearance is at stake. How to Build a Basic Calculator in Excel (5 Steps) You don’t need expensive software. Here is a manual setup: Compare worst-case vs RSS

| Part | Nom | Upper | Lower | Mean | Half-tol | Direction | Contrib (mean×dir) | Tol WC | Tol RSS² | |------|-----|-------|-------|------|----------|-----------|---------------------|--------|----------| | Spacer A | 10 | 10.1 | 9.9 | 10.0 | 0.1 | + | 10.0 | 0.1 | 0.01 | | Spacer B | 10 | 10.1 | 9.9 | 10.0 | 0.1 | + | 10.0 | 0.1 | 0.01 | | Gap (target) | - | - | - | - | - | - | 20.0 | 0.2 | 0.02 | Use worst-case when human life or mandatory clearance

Include nominal dimensions, upper tolerance, and lower tolerance.

Pick one critical gap in your current assembly. Build the Excel sheet above. Compare worst-case vs RSS. You’ll be surprised how often your initial tolerances are either too tight (expensive) or too loose (non-functional).

| Method | Formula (for additive tolerances) | Best for | |--------|----------------------------------|-----------| | | (T_total = \sum \vert T_i \vert) | Safety-critical, low volume | | Root Sum Square (RSS) | (T_total = \sqrt\sum T_i^2) | High-volume manufacturing (Cpk≥1.0) | Rule of thumb: Use RSS when you have 4+ parts in the stack and assume normal distribution. Use worst-case when human life or mandatory clearance is at stake. How to Build a Basic Calculator in Excel (5 Steps) You don’t need expensive software. Here is a manual setup:

| Part | Nom | Upper | Lower | Mean | Half-tol | Direction | Contrib (mean×dir) | Tol WC | Tol RSS² | |------|-----|-------|-------|------|----------|-----------|---------------------|--------|----------| | Spacer A | 10 | 10.1 | 9.9 | 10.0 | 0.1 | + | 10.0 | 0.1 | 0.01 | | Spacer B | 10 | 10.1 | 9.9 | 10.0 | 0.1 | + | 10.0 | 0.1 | 0.01 | | Gap (target) | - | - | - | - | - | - | 20.0 | 0.2 | 0.02 |