Window Blind Sizes: Standard Dimensions and How to Measure
The sizes stock and custom blinds are sold in, what width and length mean on a blind, how to measure for inside and outside mounting, and the slat, depth and bracket figures that decide whether a blind fits.
Stock horizontal blinds are sold in widths from about 23 to 72 in (58 to 183 cm) and in lengths of 48, 64, 72 and 84 in (122, 163, 183 and 213 cm), with 64 and 72 in the most common. Sizes are always given width × length. For an inside mount, order the exact narrowest width of the opening and let the maker deduct the clearance.
- Stock widths
- About 23 to 72 in
- Common lengths
- 64 and 72 in
- Slat sizes
- 1 in, 2 in, 2 1/2 in
- Outside mount
- +1 1/2 to 3 in per side
On this page
Standard blind sizes
Blinds are either stock (made ahead in set sizes, often trimmed in the store) or custom (made to your measurements, usually to the nearest 1/8 in). Stock sizes cover most standard US windows.
| Type | Stock widths | Stock lengths | Custom range, approx. |
|---|---|---|---|
| 1 in vinyl or aluminum mini blinds | About 23 to 72 in | 42, 64, 72 in | Width about 10 to 96 in |
| 2 in faux wood blinds | About 23 to 72 in | 48, 64, 72, 84 in | Width about 12 to 96 in |
| 2 in real wood blinds | Mostly custom | Mostly custom | Width about 12 to 72 in (wood is lighter but weaker over long spans) |
| Cellular (honeycomb) shades | About 23 to 72 in | 48, 64, 72 in | Width about 12 to 120 in, by fabric |
| Roller shades | About 23 to 72 in | 72 in (roll down as needed) | Width about 12 to 120 in |
| Vertical blinds | 78 and 104 in | 84 in | Width up to about 144 in or more |
Exact stock widths and limits vary by brand and store, so check the product page before measuring for a stock blind. Length is rarely a problem: a blind longer than the window just stacks more slats on the sill or has slats removed, while a blind that is too narrow cannot be fixed.
Metric blind sizes (UK and Europe)
Ready-made roller and Venetian blinds in the UK and Europe are commonly sold in widths of 60, 90, 120, 150 and 180 cm (about 24, 35, 47, 59 and 71 in) with drops of about 160 to 210 cm (63 to 83 in), and many can be cut down to width at home. Made-to-measure blinds are ordered to the millimeter.
Inside mount vs outside mount
Inside mount (in the window recess)
- Clean look that shows off the trim
- Width must be accurate to about 1/8 in
- Needs enough depth in the recess for the headrail
- Small light gaps at the sides (about 1/4 in per side)
Outside mount (on the trim or wall)
- Covers the whole opening; better for blocking light
- Works with shallow recesses or out-of-square frames
- Can make a small window look larger
- Hides the window trim
How to measure for inside-mount blinds
- Measure the width in three places: across the top, middle and bottom of the recess, from jamb to jamb, to the nearest 1/8 in. Order the narrowest figure.
- Do not make any deductions. The maker takes off the clearance (typically 1/8 to 1/2 in, depending on the product) so the headrail fits. Deducting it yourself as well leaves wide light gaps.
- Measure the height in three places: left, center and right, from the top of the opening to the sill. Order the longest figure so the blind reaches the sill everywhere.
- Measure the depth of the recess, from the window glass or any crank handle to the front of the frame, and compare it with the mounting depth below.
- Check square: measure both diagonals. If they differ by more than about 1/4 in, consider an outside mount.
| Blind or shade | Minimum depth | Depth for a fully flush fit |
|---|---|---|
| 1 in mini blinds | About 1 in | About 1 1/2 to 2 in |
| 2 in faux or real wood blinds | About 2 to 2 1/2 in | About 3 to 3 1/2 in |
| Single-cell cellular shades | About 3/4 to 1 in | About 1 1/2 to 2 1/2 in |
| Roller shades | About 1 to 2 in | About 2 to 3 in, depending on roll size |
| Vertical blinds | About 2 1/2 in | About 4 in |
The figures vary by brand and by blind size (wider and longer blinds have larger headrails or rolls). The spec sheet lists the exact minimum. If slats would hit a window crank or handle, mount outside or use an extension bracket.
How to measure for outside-mount blinds
- Width: measure the area to cover, usually the outside edges of the trim, then add 1 1/2 to 3 in on each side (3 to 6 in in total) to cut side light. With no trim, measure the opening and add 3 in per side.
- Length: measure from where the headrail will sit, typically 1 1/2 to 3 in above the opening or on the top trim, to 1 to 2 in below the sill or the bottom of the apron.
- Check clearance: the slats must clear the sill or window handles when they tilt. Projection brackets or spacer blocks move the blind away from the wall.
- Order the actual size. For an outside mount, the size you order is the size you get; no deduction is made.
A window with trim measuring 36 in wide and 60 in from top trim to sill: inside mount, order the opening size exactly (say 31 1/2 × 58 in). Outside mount, order about 39 to 42 in wide and 64 in long.
Slat and vane sizes
| Slat | Width (in) | Width (mm) | Notes |
|---|---|---|---|
| Micro blinds | 1/2 | About 13 to 16 | Small windows, door glass |
| Mini blinds | 1 | 25 | The standard vinyl and aluminum blind |
| Faux wood and wood | 2 | 50 | The standard wood-look blind |
| Plantation-style wood | 2 1/2 | 63 | Fewer slats, wider view when open |
| Vertical vanes | 3 1/2 | 89 | Patio doors and wide windows |
Wider slats mean fewer slats, a clearer view when open and a deeper headrail. When a horizontal blind is raised, the slats stack at the top of the window; the stack height grows with blind length and slat thickness and is listed on the spec sheet. On an inside mount, the stack covers the top few inches of glass, so mounting above the opening (outside mount) gives more light when the blind is up.
Vertical blinds for patio doors
Vertical blinds draw to one side, so they suit sliding doors. Common stock sizes are 78 × 84 in for a 6 ft (72 in) sliding door and 104 × 84 in for an 8 ft (96 in) door; both are outside mount. Draw the blind toward the fixed panel so the stacked vanes do not block the opening panel. For door sizes, see standard door sizes.
Brackets and support
- End brackets: one at each end of the headrail, about 2 to 3 in from the ends.
- Center supports: horizontal blinds wider than about 40 to 48 in usually come with one or more center supports. Space them evenly, clear of the tilt mechanism, cord lock and ladder strings.
- Hold-down brackets: fix the bottom rail on doors so the blind does not swing.
- Extension brackets: move an outside-mounted blind out from the wall to clear trim or handles, usually by 1 to 3 in.
Combining blinds with curtains? The curtain rod brackets need enough projection to clear the blind's headrail; see curtain rod bracket sizes. For curtain dimensions, see curtain sizes.
Cord safety standards
Blind cords can strangle young children. In the US, ANSI/WCMA A100.1 requires stock blinds sold in stores and online to be cordless or to have inaccessible cords, and its 2022 revision, in effect since June 1, 2024, removes free-hanging operating cords and similar hazards from custom products too. In the UK and EU, internal blinds must meet EN 13120, which requires child-safety devices on cords and chains. If you keep older corded blinds, wrap the cords on cleats mounted high on the wall, well out of a child's reach, or replace them with cordless blinds, and keep cribs and furniture away from windows.
Planning new windows? Standard openings are listed in window sizes.
Frequently asked questions
My window is 64 inches tall. Should the blind be 64 inches or longer?
For an inside mount, a 64 in blind is right; a slightly longer one also works, since the extra slats rest on the sill or can be removed. For an outside mount, go longer to cover the frame and leave room for the headrail: a 72 in blind is the usual choice.
What does blind width and length mean?
Width is the left-to-right size and is always listed first; length (also called height or drop) is the top-to-bottom size when the blind is fully lowered. For an inside mount, the width you order is the opening width and the factory makes the headrail slightly narrower; for an outside mount, it is the actual size of the blind.
How many brackets does a 70 inch blind need?
Usually two end brackets plus one or two center support brackets. Most makers add center supports on horizontal blinds wider than about 40 to 48 in, and a 70 in faux wood blind commonly ships with two. Use every bracket supplied, spaced evenly and clear of the tilt and lift mechanisms.
Can stock blinds be cut to size?
Many vinyl and faux wood stock blinds can be cut to width in the store, typically from the next stock size up, and length is shortened at home by removing slats from the bottom. Cellular shades and many roller shades are also cut in store. Real wood and motorized blinds are usually custom only.
What size vertical blind fits a sliding patio door?
Common stock vertical blinds are 78 × 84 in for a 6 ft (72 in) sliding door and 104 × 84 in for an 8 ft (96 in) door. They are outside mounted, about 3 in wider than the door frame on each side and hung above the frame.