Standard Window Size Reference
Nine common window sizes, cross-referenced against the exact order size, slat count, curtain fabric, and estimated cost each one works out to — every figure computed live by the same Blind & Shade Size, Slat Count, Curtain Fabric, and Cost calculators on this site.
Window size, order size, slats, fabric & cost
| Window size | Inside-mount order | Outside-mount order | Slats (2" slat) | Slats (1" slat) | Curtain fabric | Est. cost |
|---|---|---|---|---|---|---|
| 24" x 36" | 23.75" × 36" | 27" × 38" | 20 | 40 | 1.5 yd | $75 |
| 24" x 48" | 23.75" × 48" | 27" × 50" | 27 | 54 | 2 yd | $75 |
| 30" x 48" | 29.75" × 48" | 33" × 50" | 27 | 54 | 3.75 yd | $75 |
| 30" x 60" | 29.75" × 60" | 33" × 62" | 34 | 67 | 4.25 yd | $115 |
| 36" x 48" | 35.75" × 48" | 39" × 50" | 27 | 54 | 3.75 yd | $115 |
| 36" x 60" | 35.75" × 60" | 39" × 62" | 34 | 67 | 4.25 yd | $115 |
| 48" x 60" | 47.75" × 60" | 51" × 62" | 34 | 67 | 4.25 yd | $175 |
| 60" x 48" | 59.75" × 48" | 63" × 50" | 27 | 54 | 5.5 yd | $175 |
| 72" x 48" | 71.75" × 48" | 75" × 50" | 27 | 54 | 5.5 yd | $175 |
Order sizes come from calcBlindSize(), slat counts from calcSlatCount()(at the calculators’ standard 10% ladder overlap), curtain fabric from calcCurtainFabric() (at the default 2.0 fullness), and estimated cost from calcTreatmentCost() — the exact functions behind the calculators above, not a separately maintained table.
Light-blocking by opacity level
| Opacity level | Light blocked | Daytime privacy | Night-time privacy |
|---|---|---|---|
| Sheer / voile | 0–40% | partial | little |
| Light-filtering | 40–75% | good | partial |
| Room-darkening | 75–95% | full | good |
| Blackout | 95–100% | full | full |
These four bands, and their ranges, are the same BANDS data the Light-Blocking Opacity Selector matches to a room and priority — see our guide to what each opacity level actually blocks for how a room maps onto this table.
How to read this table
Each row starts from a single nominal window size — a width and a height, in inches — and runs it through four calculators at once. The inside- and outside-mount columns show how differently the same opening is measured depending on where the blind sits: an inside mount deducts a small clearance from the raw opening, while an outside mount adds coverage on top of it, which is why the outside-mount figure is always larger in both directions.
The two slat columns hold the drop constant and only change the slat width, which is what makes the 1-inch column consistently work out to roughly double the 2-inch column’s count — narrower slats need more of them to fill the same drop. The curtain fabric column applies the calculators’ default 2.0 fullness and standard header and hem allowances to the window’s width and height treated as a track width and finished drop, rounded up to the nearest quarter yard the way fabric is sold.
The estimated cost column is the one column built on an assumption rather than a pure geometric calculation: each window size is tagged small, medium, or large, and a representative single-window price for that tier is run through the same whole-house cost calculator, with a flat installation allowance added. Treat it as a rough sense of how cost scales with size, not a quote — see our worked example on costing a whole-house project for how the same calculator handles a real multi-window order with fees, discounts, and tax.
Frequently Asked Questions
Are these the exact sizes my own window will be?
Almost certainly not exactly — real windows vary from these common nominal sizes by an inch or more, and every guide on this site tells you to measure your own opening in three places rather than assume a standard size. This table exists to show how the size calculator, slat count, curtain fabric, and cost figures move together across a realistic range of sizes, not to replace measuring your own window.
Why does the inside-mount order size differ from the outside-mount size for the same window?
An inside mount is measured to fit inside the recess, so a small clearance is deducted from the raw opening width. An outside mount sits on the wall or frame above the opening, so coverage is added on the sides and top instead. Every order size in the table below comes from calling the same calcBlindSize() function behind the Blind & Shade Size Calculator, with the mount type as the only thing that changes.
Why do 1-inch slats need exactly double the 2-inch slat count?
Slat count comes from dividing the drop by the ladder-tape pitch, and pitch is just the slat width reduced by the overlap percentage. Halving the slat width halves the pitch, which — for the same drop — roughly doubles how many slats fit. It isn't a coincidence built into this table; it's the same arithmetic calcSlatCount() runs for the Slat Count & Ladder Spacing Calculator, just visible across several sizes at once.
Is the estimated cost column a real quote?
No — it's an illustrative single-window cost using a representative price for each size tier (small, medium, large) run through the same calcTreatmentCost() function behind the Window Treatment Cost Estimator, plus a flat installation assumption. Real prices vary by material, retailer, and region. Use the cost estimator directly with your own quoted prices for an order you're actually about to place.
Every figure above is a starting point for comparison, not a substitute for measuring your own window. Always measure the actual opening — width in three places, height in three places — before ordering a made-to-measure blind, shade, or curtain.
Use it with
- Blind & Shade Size Calculator— run your own window’s exact measurements instead of the nominal sizes above.
- Slat Count & Ladder Spacing Calculator — get a slat count for a specific slat width and overlap rather than the two widths shown here.
- Curtain Fabric Calculator — work out yardage with your own fullness ratio and pattern repeat.
- Window Treatment Cost Estimator — price a real, multi-window order with your own quoted prices, fees, discount, and tax.
- Common Blind Measuring Mistakes — the guide version of the order-size columns above, with worked examples of what goes wrong.