A visual inspection sampled under ISO 2859-1 tells you about defects such as holes, stains and broken stitches. Measurements need their own plan. Measuring every garment in the visual sample would take too long, so inspectors usually measure a smaller number of pieces. If that number and the tolerances are not written down, "measurements OK" can mean very little.

How many pieces

A common approach is to measure a set number of pieces per size and per colour, rather than a total for the order. Some buyers use a few pieces per size per colour, more on a first order or a new factory. Whatever you choose, state it in the inspection booking so it is the same every time. If an order has many sizes and colours, prioritise core sizes and any colour with different fabric.

Which points

Measure the points that drive fit and complaints: chest or body width, body length, sleeve length, shoulder or across back, and hem width. For hoodies add hood height and cuff and hem rib. Use the same measuring method as your spec sheet, with clear diagrams, so the factory and the inspector measure in the same way.

Tolerances

Give a plus and minus tolerance for each point, not one tolerance for everything. Larger measurements such as chest can carry a larger tolerance than small ones such as neck drop. Tolerances should reflect what affects fit and what the factory can realistically achieve with knit fabric.

Pass and fail

Decide what happens if some measurements are out. For example, a single point slightly out may be noted, while several points out on the same size may fail the size. Record actual measurements, not only pass or fail, so you can see trends.

Fit after washing

Fit complaints often come after washing. Add a wash-and-measure check on a few pieces using a named procedure such as ISO 6330, and confirm fabric weight with a named method such as ASTM D3776.

Compare measurement results with return reasons by size. If one size keeps generating fit returns while inspections pass, the tolerance or the spec itself may need review, not only the factory's sewing.