Almost every jacket programme that has to be redone was sized the same way: someone collected chest measurements in a spreadsheet.

Why chest is the wrong first number

It is the easiest number to collect and the least decisive. It is also the one that can be altered afterwards, along with sleeve, waist and length.

The shoulder cannot, and two people with identical chests can have visibly different shoulders.

Use fit samples, not a form

Send two or three shoulder blocks around the team and have people try them. It takes a week and it removes the single largest source of error.

For a mixed team, include both the men’s and the women’s block. Sizing everybody from one of them guarantees that part of the team is in the wrong pattern.

Consider an unstructured block for the hardest cases

Because it has less built-in shoulder structure, an unstructured jacket has less of the un-alterable part to be wrong.

One unstructured block will fit a noticeably wider range of builds acceptably than one structured block will. It is less formal, so it is a trade rather than a free win.

Budget for alterations, because they are normal

Sleeve, waist and length corrections are expected on a tailored garment and are not a sign that anything went wrong.

What should never be on that list is a shoulder correction. If it is, the wrong block was chosen and the answer is a different jacket, not a tailor.

Have the records held before you start

Individual measurements, the chosen block, the maker and the cloth reference.

New starters can then be ordered in a day, and a top-up in two years is the same jacket rather than nearly the same one.