When you need to price a restring or match replacement slats, you first need the count. Divide the window height by the slat spacing and round down, and you have how many slats stack up the blind.
A 48-inch blind with 2-inch spacing has 24 slats.
The example
Three windows, each with a height in inches and the spacing between slats.
| A | B | C | D | |
|---|---|---|---|---|
| 1 | Window | Height in | Spacing in | Slats |
| 2 | Bedroom | 48 | 2 | 24 |
| 3 | Living | 60 | 2 | 30 |
| 4 | Door | 66 | 1.5 | 44 |
The formula
Height over spacing is the raw count; rounding down keeps it whole:
How it works
Two inputs:
B2is the window (or blind) height in inches.C2is the spacing between slats — 2 inches for a standard horizontal blind, less for mini-blinds.ROUNDDOWN(...,0)rounds down, since a partial slot at the top does not add a whole slat.- Use the actual drop of the blind, not the window opening, if they differ.
Multiply the slat count by a per-slat price for a replacement-slat quote, or use it to size a restring.
Try it: interactive demo
Enter the blind height and the spacing between slats, in inches.
Variations
Replacement-slat cost
Multiply the count by a per-slat price.
Ladder-string rungs
The number of ladder rungs matches the slat count for a restring.
Pitfalls & errors
Slat spacing is not the same as slat width. A 2-inch slat overlaps its neighbor, so use the vertical spacing between slats, not the face width, in the division.
Measure the blind's actual drop for an existing unit. The window opening can be taller than the blind, which would overstate the slat count.
Practice workbook
Frequently asked questions
What spacing should I use?
Why round down?
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