How to measure your window for blinds
Five minutes with a steel tape saves a remake. Inches, to the nearest 1/8.
Inside or outside mount, where exactly to put the tape, and the three measurements to send us. Five minutes with a steel tape saves a remake.
What you need
- A steel tape, not a cloth one — cloth tapes stretch and read long.
- Somewhere to write the numbers down as you go.
- Inches, to the nearest 1/8. Do not round to the nearest inch.
Inside (reveal) mount
The blind sits inside the window opening. Tidier, keeps the sill usable, and always lets a sliver of light past the edges.
- Measure the width of the opening at the top, the middle and the bottom. Openings are rarely square. Write down the narrowest of the three.
- Measure the height at the left, the centre and the right. Write down the longest of the three.
- Check the depth of the reveal — how far back the frame sits from the wall face. Tell us this number; it decides whether the blind fits fully inside.
- Send the numbers exactly as measured. We make the deduction for clearance; if you deduct as well, the blind ends up too narrow.
Outside (face) mount
The blind covers the opening and overlaps the wall around it. The only way to get a genuinely dark bedroom, and the answer when the reveal is too shallow.
- Decide how much overlap you want. Two to three inches on each side is normal, and more is better for blackout.
- Measure the total width you want covered, including that overlap.
- Measure from where the top of the blind will sit down to where you want it to end — below the sill for blackout, level with it otherwise.
- Check there is a clear run of wall or frame for the brackets, with no AC unit, grille or curtain rail in the way.
The four mistakes we see most
- Measuring the glass instead of the opening. Always measure the opening.
- Measuring once. Windows are not square; three readings take ten seconds.
- Deducting for clearance yourself. Send the real numbers and let us do it.
- Forgetting the handle. A window handle, a grille or a security bar changes the mount type entirely — tell us it is there.
Send us the numbers
Width, height, and inside or outside mount. That is enough for a written quote. A photo of the window helps us catch anything you did not think to mention.
Frequently asked questions
Do I measure inside the window frame or outside it?
Both are valid, and they give different results. An inside (reveal) mount looks tidier and keeps the sill usable, but a little light always escapes at the edges. An outside mount overlaps the frame by two to three inches on each side and is the only way to get a genuinely dark bedroom. Tell us which you want and measure accordingly — our /measure guide walks through both with the exact points to record.