Fastener Manufacturing & Thread Rolling calculator

Inspection Sample Size Calculator

Fastener inspection workload changes with lot count, characteristic count, sampling level, and retest expectations. This calculator estimates how many sample checks QA should plan after coverage and acceptance assumptions are applied.

What this calculator does

  • Estimate total fastener inspection samples from planned lots, checks per lot, coverage factor, and accepted sampling yield.
  • Use it when planning QA workload for dimensional, thread, torque, proof-load, plating thickness, or visual inspection on fastener lots.
  • Converts sampling points, per-point sample size, coverage, and acceptance assumptions into planned fastener inspection sample workload.

Formula used

  • Gross inspection samples = samples per inspection point × inspection points or lots
  • Planned accepted samples = gross samples × coverage factor × first-pass acceptance factor

Inputs explained

  • Samples required per inspection point: undefined
  • Inspection points or lots: undefined
  • Sampling coverage factor: undefined
  • First-pass acceptance factor: undefined

How to use the result

  • Use it before releasing QA capacity for lot inspection, PPAP support, receiving inspection, or containment sorting.
  • It does not replace the customer sampling plan, AQL table, ASTM/ISO standard, or control plan; verify the required sample size before release.

Common questions

  • What is an inspection point? It can be a lot, cavity, machine stream, heat, coating batch, characteristic, or control-plan checkpoint depending on how your QA plan is written.
  • Can this replace an AQL or customer sampling plan? No. Use the customer specification, AQL table, or control plan to determine required samples, then use this calculator to plan workload.
  • What should first-pass acceptance include? Include expected retests, gauge disputes, suspect lots, or additional checks caused by thread, head, plating, torque, or tensile failures.
  • What decision does the result support? Use the sample workload to schedule inspectors, reserve gauges, estimate lab time, and decide whether lot release could delay shipment.

Last reviewed 2026-05-12.