Measuring for window blinds sounds simple until the blind turns up 15mm too narrow. One rule prevents almost every problem: measure the opening, never the glass, always in millimetres, at three points. Apex measures on site at no charge, but most homeowners want to understand the numbers first. Here is how window blinds are actually measured in Singapore flats and condos.
Should You Measure For Window Blinds Yourself?
A rough self-measure is useful for setting a budget and comparing quotes on the same basis. Placing the order from it is another matter. Ask for a professional site measure on any window blinds that are recessed, any bay window, anything motorised, and any zip blind system, because those have very little tolerance for error.
There is a commercial reason to ask. When the supplier measures, the supplier carries the cost of a remake. When you supply your own numbers, that cost sits with you.
Inside The Recess Or Outside The Frame?
Window coverings mount one of two ways. A recess mount sits inside the opening and looks cleanest, but needs depth. A face fit sits on the wall outside, blocks edge light far better, and quietly rescues an opening that is not square. If you have a curtain box or dropped ceiling, settle the ceiling or wall mount decision before ordering.
Depth usually decides which window blinds will work for you.
Minimum Recess Depth By Blind Type
Slat width matters, which is why venetian blinds appear twice below.
| Blind type | Minimum depth | If you have less |
| Roller blinds | ~74mm | Face fit or slimmer cassette |
| Venetian, 50mm slat | ~65mm | Use a 25mm slat |
| Venetian, 25mm slat | ~50mm | Face fit |
| Vertical blinds | ~57mm | Face fit |
| Zip blind system | Flat face both sides | Face fit to reveal |
Check depth at the top, middle and bottom and work from the shallowest. Tiling and repainting both eat into a reveal.
How To Measure Width And Drop
Use a rigid metal tape. The method is the same for every type of window blinds, and a cloth tape stretches enough to cost you one. Work in millimetres, never inches.
For a recess mount, measure the width in three places and the drop in three places, taking the smallest of each.
For a face fit, take the widest measurement, then add at least 50mm each side and 70mm above the opening. That overlap stops light bleeding around the edges.
Do Not Apply Your Own Deduction
This is the most common self-measure failure. Send the raw opening size and state which mount you want. The workshop already takes roughly 10mm off the width and up to 10mm off the drop so the blind clears the reveal. Roller blinds are the exception and take only about 2mm. Deduct first and it happens twice, so the blind arrives visibly short.
Why Roller Blinds Look Narrower Than You Ordered
Roller blinds are quoted bracket-to-bracket, not by fabric width. The fabric finishes around 32mm narrower than the size you supplied, and the gap on the control side is slightly wider. This is normal, and it is why a finished blind can look different from what you pictured.
Measuring The Window Types In Singapore Homes
| Window type | Best mount | Suits | Watch for |
| HDB casement | Face fit | Roller, venetian | Handles over 20mm |
| Top-hung / awning | Face fit | Roller blinds | Sash opening arc |
| Sliding window | Either | Roller, venetian | Shallow reveal |
| Full-height glazing | Ceiling or face | Custom blinds | Curtain box |
| Bay window | Recess, per panel | Roller blinds | Uneven panels |
| Sliding door | Face fit | Vertical blinds | Stack side |
| Balcony / yard | Face fit | Zip blind system | Flat side channels |
On a bay window, measure every panel separately. HDB and condo bays are almost never symmetrical, and one shared measurement guarantees at least one poor fit. For sliding doors, vertical blinds remain the practical choice, but decide which side the stack parks on first. Watch handles throughout: anything projecting over 20mm will foul a recessed blind, so face fit it or use spacer brackets.
The Obstructions That Cause Most Remakes
Most window blinds that go back to the workshop do so for one of these five reasons.
- Aircon ledges and trunking. Measure to the obstruction, not past it.
- Curtain boxes and false ceilings. These change the usable drop entirely.
- Window and invisible grilles. Agree the fitting order with your installer first.
- Openings that are not square. Face fit hides it, recess mount exposes it.
- Measuring the glass, not the opening. Still the top cause, and these sizing and installation mistakes are avoidable.
When To Measure During Your Renovation
Measure after the false ceiling and cornices are in, after aircon trunking is boxed up, and after painting. Earlier than that, you are measuring a surface that will not exist by installation day. In a BTO, measure after any window rectification during the defect period. Planning your window coverings around the renovation timeline saves far more than shopping on price.
Common Questions About Measuring For Window Blinds
Do I measure the window frame or the glass?
Always the opening, frame edge to frame edge. Measuring the glass produces a blind that is too small on every side and leaves visible light gaps once installed.
Do custom blinds need different measurements to standard sizes?
Custom blinds are made to your exact opening, so the measurement matters more, not less. Standard sizes assume you will absorb the difference with overlap. Custom does not.
Can I measure before my renovation is finished?
For budgeting, yes. For ordering, no. Plaster, tiling, false ceilings and repainting all change the opening, sometimes by 20mm or more.
Get Your Window Blinds Measured Right The First Time
Most measuring problems come from three things: measuring the glass, forgetting the handle, or deducting a figure the workshop was going to deduct anyway. Get those right and your window blinds will fit the first time. If you would rather not climb a ladder, our team measures free of charge across Singapore. Get in touch and we will bring samples along.
