Textiles & Apparel Manufacturing calculator

Apparel Size Curve Run Window Calculator

Apparel size curve volume is a scheduling check that tells a planner whether the full size-curve run, every size in its ratioed quantity, plus its changeover buffer will actually fit inside the hours you have on a line. Production planners and line schedulers use it before committing a cut order to a shift so they don't strand a partial curve or blow a ship date. Because a size curve must ship complete, running out of window on the last size is a real risk. This tool subtracts required run time and buffer from the available window and tells you plainly whether the work fits.

What this calculator does

  • Check whether a full size-curve production run plus its changeover buffer fits inside the available line window, so cut orders are only committed when the hours are really there.
  • Use it when a size-curve cut order needs a fast does-it-fit check against the shift window before it is committed to the line.
  • It subtracts required run time and changeover buffer from the available window and reports whether the size-curve run fits inside it.

Formula used

  • Remaining buffer = available production window - required size-curve run time - changeover and buffer time
  • Positive buffer means the work fits inside the available window.

Inputs explained

  • Available production window:
  • Required run time for size curve:
  • Changeover and buffer time:

How to use the result

  • Use it during shift planning to confirm a size-curve cut order can be completed before the window closes.
  • It treats run time as a single block; it won't model overlapping operations, split lots, or overtime that could rescue a run that technically doesn't fit.

Common questions

  • How do I know if a size curve run fits in my shift? Subtract the required run time and the changeover buffer from the available window. If what's left is zero or positive, it fits. With a 10-hour window, 8 hours of run time, and a 1.5-hour changeover buffer, 0.5 hours remain, so the run fits.
  • What is a size curve in apparel production? A size curve is the ratio of quantities across sizes, for example 1:2:3:2:1 across XS-XL, that a style must be produced and shipped in. Because retailers order full curves, you generally can't ship until every size in the curve is complete.
  • Why does the buffer time matter so much? Changeover and buffer time covers style setup, thread and needle changes, and first-piece approval. On short runs this can rival the sewing time itself, so leaving it out of the window check is how planners overcommit a line.
  • What does 'inside window' mean in the result? It's a yes/no flag: the run and its buffer land within the available hours. 'Inside window' means you can commit the cut order to this shift; a negative margin means you need overtime, a second shift, or a lighter curve.
  • Can I use this for multiple styles on one line? Only by summing their required run times and buffers into a single check. This version treats the window as one block, so for a complex multi-style day you'd run it per style and reconcile the totals manually.

Last reviewed 2026-08-13.