Why nominal sizes do not travel
Dust bags are quoted against an item, not a size chart. Two handbags described as 'medium totes' can differ by several centimetres in depth once handles are folded, and a bag sized for one will strain or swim on the other.
This matters more than it sounds, because a dust bag that is slightly too small is not slightly wrong — it either will not close over the widest point, or it closes under tension and marks the item it was bought to protect.
Measure the item as it will be stored
Width at the widest point. Not the base — the widest horizontal measurement, which on a structured handbag is usually across the body and on a shoe is across the instep.
Height as stored. With handles folded, collapsed or upright exactly as the item will actually sit inside. A boot stored upright and the same boot laid flat are two different specifications.
Depth. The front-to-back measurement at the deepest point, including any hardware, buckle or heel that stands proud of the body.
Pairs and sets. If two shoes go in one bag, measure them positioned as they will be packed — sole to sole is narrower than side by side.
What the closure needs from the height
A drawstring bag does not use its full height. The channel at the top consumes some of it, and the gathered fabric needs somewhere to sit once the cord is drawn — so the finished internal height is always greater than the item's height.
How much greater depends on the fabric weight and the channel construction, which is why the allowance is confirmed on a physical sample rather than published as a rule. Send the item's measurements and the allowance is specified from them.
The same applies around the body: the internal circumference has to clear the item's widest cross-section with enough slack that the cord closes without the seam taking the load.
The mistakes that cause a resample
1. Measuring the item empty when it will be stored stuffed, or stuffed when it will be stored flat. Decide which, then measure that state.
2. Forgetting the handles. Handles folded inside change the depth; handles left upright change the height. Both are valid — say which one you mean.
3. Sizing to one product in a range and assuming the rest fit. If one bag has to cover several product variants, send the largest and the smallest and the range can be specified deliberately.
4. Ignoring print placement. A logo centred on the flat panel can end up inside a gather once the bag is drawn closed. Confirm placement on a drawing of the finished bag, not on a flat rectangle.
What to send with the enquiry
Width, height and depth of the item as stored, with a note on how handles or heels are positioned; the number of product variants one bag size has to cover; whether the bag ships inside the product carton or separately; and the artwork with intended placement.
With those, the internal size, the closure allowance and the print area are specified together and confirmed on a pre-production sample before bulk.