By Zencalcy Editorial TeamLast reviewed About us
True position is twice the radial distance between where a feature is and where the drawing says it should be. The doubling matters: a hole 0.005 inch off in both X and Y deviates 0.0141 in true position, which may exceed a 0.010 tolerance.
Position deviation from X and Y coordinates.
TP = 2 × √(ΔX² + ΔY²)
For a hole, the tolerance zone is a cylinder, which is why the formula doubles the radial error. MMC modifiers allow bonus tolerance equal to the departure from maximum material condition.
| Symbol | Meaning |
|---|---|
| ΔX, ΔY | Deviation from the basic coordinates. |
| TP | True position diameter. |
TP = 2 × √(0.005² + 0.005²) = 0.0141 in — outside a 0.010 tolerance.
Continue with the Beam Deflection Calculator, Beam Load Calculator, Bending Stress Calculator, or the Wood Beam Span Calculator — or browse more structural & workshop and all construction calculators.
The tolerance zone is a diameter centred on the true position, so the allowed radial deviation is half the stated tolerance.
Results use standard construction estimating arithmetic: volumes from measured area and depth, unit weights from published material densities, and code-referenced spans or clearances where the page names a code. Quantities are rounded up to whole saleable units and include the stated waste allowance. These tools are planning aids, not structural design, and do not replace a licensed engineer, a local code check, or a contractor's site measurement.
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Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026