Window blinds are shades made from uniform horizontal slats that are lightweight, can be tilt-adjusted for light control, and pull up to open to an unobstructed view. Blinds may be metal, plastic, wood, veneer, mini or fabric-covered. Most blinds are metal, wood or mini-blinds, and you can generally find stock blinds at home improvement and big box stores. Stock blinds, according to the Window Covering Manufacturers Association, are window coverings that are made to standard sizes and may be adjusted to fit the window. So the most common window sizes determine the easiest-to-find and most-economical ready-made blinds.

Standard Sizes

When selecting window blinds, consider three measurements: window length, width and depth. Depth determines the size of slats, but standard window lengths are:

  • 36 inches
  • 48 inches
  • 60 inches
  • 72 inches

Standard window widths are:

  • 24 inches
  • 36 inches
  • 48 inches
  • 60 inches

Older homes or custom windows will vary considerably and may require custom-manufactured blinds. But a standard size can usually be trimmed in the store to make it fit inside your not-quite-standard window. This is often the most economical solution.

Slat Sizes

The slats can be tilted, opened precisely horizontally for the most light, or closed for privacy or to block light. Deeper windows look best with the widest slat sizes, and small, shallow windows work with the narrowest slats. Common slat widths are 1/2 inch, 1 inch or 2 inch -- the most popular width. The wider the slat, the heavier the blind, so a large window that can handle the look of a 2 1/2-inch slat might require a light, synthetic slat material to make the weight of the blinds manageable. When choosing classic wide wood slats, consider the weight; extra-wide slats might make real wood an impractical choice for large windows.

Mini-Blinds and Measuring

Skinny, lightweight blinds with very narrow slats are called mini-blinds and look best in modern decor and covering smaller windows. Those slats are typically 1/2-inch deep and hung within the window frame; the width and length of the blind corresponds to standard window sizes. To for inside-mount blinds -- the most typical mounting method for any blind -- take three precise measurements for the width: from inner frame to inner frame at the top, middle and bottom of the window, noting the width to the nearest 1/8 inch. Then find the height by measuring to the nearest 1/8 inch from the inside top of the frame to the sill at left, center and right. For overlapping blinds that rest outside the frame, add 1 1/2 to 3 extra inches to the window width.