Quality & Metrology calculator
Prescribed Sampling Plan Size Calculator
Turn an approved inspection percentage and minimum count into a whole-unit sample for a known lot.
What this calculator does
- Turn an approved inspection percentage and minimum count into a whole-unit sample for a known lot.
Formula used
- Percentage quota = round up(lot size × prescribed percentage ÷ 100)
- Required sample = max(percentage quota, minimum sample)
- Actual sampling share = required sample ÷ lot size × 100
- Units outside sample = lot size − required sample
- Sample above minimum = required sample − minimum sample
Inputs explained
- Lot Size: Whole units in the lot covered by this inspection instruction.
- Prescribed Sampling Rate: Approved sampling percentage, entered in increments of 0.0001 percentage points.
- Minimum Sample Count: Smallest whole sample required by that same instruction.
How to use the result
- Best suited to a lower prescribed sampling Rate, a higher prescribed sampling rate.
- A percentage quota supplies no detection probability or acceptance number. This is not an ANSI/ASQ or ISO sampling-table lookup.
Current U.S. benchmarks
- U.S. manufacturing runs at 75.7% of capacity (Federal Reserve, Aug 2026). New factory orders are up 8.5% year over year (Census).
Common questions
- Does ten percent mean ninety percent confidence? No. Inspection share and confidence are different quantities. Detection depends on the defect model, sample size and decision rule.
- Why round upward? A sample contains whole units. Rounding upward meets the prescribed percentage instead of inspecting less than requested.
- Can the minimum exceed the lot? No. Correct the lot size or inspection instruction. A sample of distinct lot units cannot contain more units than the lot.
- Where do acceptance numbers come from? Use the approved sampling plan or applicable standard. This quota calculation does not choose how many defects a lot may contain.
Related guides
Last reviewed 2026-10-06.