Sizes, and the trap in them

This is the step that costs first time buyers the most money, and it is entirely preventable. Bed sizes are not standard across markets and the names actively mislead: a king in the United States, a king in Britain and a king in Europe are three different beds. So are the duvets that go on them, and so are the pillows. A cover cut to one market and sold in another is not a fit complaint, it is stock that cannot be sold at all.

Send a size grid in centimetres. Every piece, every size you intend to sell, the finished measurement, and a plus or minus tolerance on each one. Never a size name on its own. If you do not have a grid, build it from the product you are replacing on your own shelf, measured, rather than from a competitor's website.

Pocket depth is a separate decision. A fitted sheet is cut to a mattress depth, and mattresses have got deeper over the years. State the depth you are cutting for and state the elastication. This one line prevents the most common return in bed linen.

Say whether the grid is before or after washing. Cotton shrinks, and the mill cuts oversize to land on your finished size after the first wash. Whether your numbers are the cut size or the washed size is a real question with a real answer, and it must be written down rather than assumed. The shrinkage allowance itself is agreed at step 10, tested rather than promised.

Towels and table linen have the same trap in a milder form: a bath sheet and a bath towel are different products in different markets, and a rectangular tablecloth sold in one market is a different size in another. Measure what you are replacing.