Online selling
Write size details a buyer can use
Measure the item yourself, write each value with its unit and say where the measurement starts and ends. A tag reading "Large" is a label, not a measurement, so list both and keep them separate. Buyers can then compare against something they own.
A text to start with
I'm listing [item]. The label says [labeled size]. I measured these dimensions with [tool]: [dimension, value, unit, and the two points measured between]. Measurements may vary by about [tolerance, if known]. Write a size section that gives measured values first and the labeled size separately. Use one unit throughout unless I give both, and don't estimate any value I haven't supplied.
Example request. Change the details to fit your situation.Size details worksheet
Item: [ ] Size printed on label, copied exactly: [ ] Measuring tool: [ ] Unit used throughout: [ ] Dimension name: [ ] Value and unit: [ ] Starting point: [ ] Ending point: [ ] Measured flat, stretched or assembled: [ ] Dimension name: [ ] Value and unit: [ ] Starting point: [ ] Ending point: [ ] Weight, if relevant, value and unit: [ ] Tolerance or variation note: [ ] Measurements rechecked on: [ ] Sentence for the listing explaining how I measured: [ ]
Units and measuring points
Check units first: inches on one line and centimeters on another, or a value with no unit at all. Confirm each number matches the unit you intended. Make sure each dimension names its endpoints, because "width" can mean several things on the same item. Keep the labeled size apart from your measured values, since a tag may not match the item. Check that a measurement taken flat is not described as if the item were stretched, packed or worn. If you round, say so.
Ask another agent to check the result
Check every value here for unit consistency, including any unit that is missing. Separate the measured dimensions from the size printed on the label, and flag anywhere the two are blended. Tell me which dimensions lack clear starting and ending points.
Remeasure what looks off
Measure any inconsistent dimension a second time, using the same tool and the same points. Compare your numbers with the photos, especially any shot that includes a ruler. Add a short line saying how you measured. If a buyer later reports a different number, your measurement endpoints let you correct the listing instead of arguing the point.