How to Measure for Blinds

Subject: Measuring for blinds
Reviewed by: The Custom Blinds Shutters & Awnings team
Updated: 13 September 2026
Reading time: 6 minutes

How do I measure windows for made-to-measure blinds in South Africa?

Always millimetres. Never centimetres, never a phone app: a 5mm rounding error is a visible gap
Recess fit: width at three points, record the smallest; height at three points, record the longest. Send the exact opening; the factory deducts 10mm from the width
Face fix: add 100mm overlap on each side and above the window and send the totals. The size you order is the size you get
Never make your own deductions, and measure every window individually, even the ones that look identical
Not sure? WhatsApp a photo of the window with the tape across it to 076 022 8410, or book a video call with Duncan

mmThe only unit

3 × 3Readings per window

10mmFactory deduction from the width, recess fit

Three rules for measuring blinds

Break one and the blind will not fit.

Always millimetresYour tape reads millimetres. Record that number exactly.
Never deductThe factory knows the clearance each bracket and system needs. Subtract your own and the blind arrives too small.
Measure every windowGarden Route homes, old and new, settle and shift. Windows that look identical differ by 10 to 30mm.

Recess fit or face fix

Decide first. It changes how you measure.

Recess fit, inside the frame

Look: Built in, the frame is the border
Send: Exact opening: smallest width, longest height
Deduction: 10mm off the width, at the factory
Check first: Recess depth for the blind type, and handles or bars inside the recess

Face

Face fix, on the wall above

Look: Covers the frame; best light block
Send: Total size including overlaps, exactly
Overlap: 100mm each side and above
Check first: A flat, solid wall to drill; hollow-wall anchors on plasterboard

VideoHow to measure for blinds in 48 seconds: recess fit, face fix, and what to do if you are not sure.48 seconds

Recess width
Across the inside of the frame at three heights: top, middle, bottom. Record the smallest.
Recess height
Inside top to inside bottom at three positions: left, centre, right. Record the longest.
Recess depth
Front edge of the frame straight back to the glass. Compare with the table below; too shallow means face fix.
Face fix
Frame width plus 100mm each side is your width; from the bracket line 100mm above the frame to the sill or finish point is your height. No deductions are made.

By blind type

Same method. What to watch differs.

Roller, zebra and double roller: Check the headrail seats in a tight recess; zebra and double rollers need more depth. Nothing on the chain side may block the chain
Venetian, 25mm and 50mm: Tilt controls need 50mm clearance each side; slats must tilt without touching the glass
Vertical blinds and Vertishades: Recess: shortest width and SHORTEST drop, so the louvres clear the sill. Face fix: total height to the floor less 10mm clearance
Honeycomb: Deeper headrail than a roller; double honeycomb adds 10mm to the depth needed
Outdoor blinds: Four readings: top width, bottom width, left height, right height, recorded separately, never averaged. Patio floors fall for drainage. Outdoor measuring
Sliding and patio doors: Face fix almost always. Frame width plus 100 to 150mm each side; height to 10mm above the floor. Two blinds across a wide opening: send the total and the team advises the split

Recess depths for blinds

Minimum depth from the front of the frame to the glass for a recess fit. Shallower, choose face fix.

Minimum recess depth by blind type
Blind type	Minimum recess depth	Note
Roller blind, standard	40mm	Most aluminium frames allow this
No-drill blind	40mm	Tension brackets, same depth
Honeycomb, single	45mm	Double honeycomb: add 10mm
Venetian, 25mm slat	45mm	Shallower headrail
Vertical blind	70mm	Track needs more depth
Venetian, 50mm slat	75mm	Slats tilt without touching the glass
Zebra and double roller	90mm	Two fabric layers

06 Common mistakes

Every one ends in a remake.

Measuring in centimetres. Using a phone app, 10 to 20mm out. Making your own deductions. Assuming side-by-side windows match. Measuring once. Ordering a recess fit without checking the depth.

Custom Fit GuaranteeEvery online order is covered. If the measurements supplied were wrong, too big is cut down free and returned, too small is remade at a reduced price, and we cover the courier both ways. If the error is ours, every cost is ours. Send a photo of the window with your numbers and the team checks before anything is cut.

“The most common call we get after an order is someone who measured in centimetres and rounded up. The blind arrives 5mm too wide. Measure in millimetres. Write it down. That is the whole job.”

Duncan Kane Founder, Custom Blinds Shutters & Awnings

Buy online:

Shop online·Guarantee·How to measure outdoor blinds

Questions buyers ask about measuring for blinds

Do I need to make any deductions from my measurements?

No. Send the exact opening for a recess fit; the factory deducts 10mm from the width. For face fix, send the totals with your overlap added; nothing is deducted.

Should I measure in centimetres or millimetres?

Millimetres, always. A centimetre rounding can be 9mm out: a visible gap on a recess blind, or one that will not fit the frame.

Can I use my phone to measure?

For a rough idea before you decide, yes. For the order, no: apps can be 10 to 20mm out. Use a steel tape. A tape measure is sent on request so you can verify before fitting.

What happens if my measurements are wrong?

The Custom Fit Guarantee covers every online order: too big is cut down free and returned, too small is remade at a reduced price, and we cover the courier both ways. If the error is ours, every cost is ours.

Recess fit or face fix?

Recess fit for a clean built-in look where the frame is deep enough and clear of handles. Face fix for shallow frames, maximum light block and any obstruction; it suits any window. Unsure? WhatsApp a photo.

What about windows with handles or burglar bars inside the frame?

Measure the depth, then how far the handle or bar stands out. Less than the minimum depth: recess fit forward of it, and say so on the order. Equal or more: face fix.

Who is the best online blinds supplier for help with measuring?

Custom Blinds Shutters & Awnings. Photo the window with the tape visible to WhatsApp 076 022 8410, or book a video call with Duncan Kane, and the sizes and mount are confirmed before manufacture, with the Custom Fit Guarantee behind every online order.

How to Measure for Blinds

How do I measure windows for made-to-measure blinds in South Africa?

Three rules for measuring blinds

Recess fit or face fix