Standard vs custom window size
Enter a width and height to see whether it matches a common stock size or is a custom order — which drives cost and lead time.
A 36.00 × 60.00 in window is a common stock size — cheaper and faster. The LABELED size list is a planning guide — confirm availability with the supplier.
Calculator inputs
Windows come two ways: stock (a standard nominal size a manufacturer keeps in production) and custom (built to a size you specify). Stock sizes are cheaper and ship faster; custom sizes cost more and take longer. Knowing which you need shapes both the budget and the schedule.
This reference checks your width and height against a labeled list of common stock sizes. A whole-inch size on the list reads as stock; a fractional dimension — the norm when a replacement is measured to an existing opening — almost always means a custom order, even if it is only off by a fraction of an inch.
Formula
A size is treated as a common stock size when it is a whole-inch width × height that matches the labeled stock list; otherwise it is a custom order. Fractional dimensions (e.g. 33¼ × 57½) are custom by definition.
Worked example
A 36 × 60 inch double-hung is on the stock list — a common stock size.
A 33.25 × 57.5 inch window — the kind of measurement you get from an existing opening — is not a whole-inch stock size, so it is a custom order.
What to check first & common mistakes
- Replacements are usually custom. Insert windows are measured to the existing frame and ordered to the eighth of an inch, so most replacement windows are custom even when a similar stock size exists.
- Stock lists vary by brand. The chart here is a planning guide; every manufacturer’s stock table is a little different — confirm availability with the supplier.
- Rounding down. If you are close to a stock size, you generally size down (never up) to the nearest available unit and make up the difference with the shim gap — never force a unit into a smaller opening.
- Cost and lead time. Custom adds to both. If the budget is tight and the opening allows it, a stock size can save money — carry the size into the cost-by-type estimator.
Reference table
Labeled common stock window sizes (planning guide — confirm availability with the supplier).
| Nominal stock size | United inches |
|---|---|
| 24 × 36 in | 60 UI |
| 24 × 48 in | 72 UI |
| 28 × 54 in | 82 UI |
| 30 × 36 in | 66 UI |
| 30 × 48 in | 78 UI |
| 30 × 60 in | 90 UI |
| 32 × 48 in | 80 UI |
| 32 × 54 in | 86 UI |
| 36 × 48 in | 84 UI |
| 36 × 54 in | 90 UI |
| 36 × 60 in | 96 UI |
| 36 × 72 in | 108 UI |
| 48 × 48 in | 96 UI |
| 48 × 60 in | 108 UI |
| 60 × 48 in | 108 UI |
| 72 × 60 in | 132 UI |