How to Measure Blinds Correctly: The Complete UK Guide to Getting It Right First Time

Why Accurate Measuring Matters More Than You Think

Getting your blind measurements wrong is one of the most frustrating and expensive mistakes you can make when ordering made-to-measure blinds. Unlike off-the-shelf products you can simply return, a made-to-measure blind is manufactured specifically for your window. If the measurements are wrong, the blind will not fit correctly — and the cost of replacement falls on you.

Based on the volume of queries we receive, the vast majority of fitting problems trace back not to defective products, but to incorrect measurements taken at the very start. This guide exists to prevent that from happening to you.

What Tools Do You Need Before You Start Measuring?

Do I need a special tape measure, or will any tape measure do?

A steel tape measure is essential. Fabric or retractable cloth tape measures flex and sag, which introduces inaccuracy. Your steel tape measure should be longer than the widest dimension of your window. For very large windows, a laser measure is a reliable alternative that eliminates the risk of the tape bowing across the span.

The full list of tools you should have to hand before taking a single measurement:

• Steel tape measure (longer than your window width)
• Laser measure (optional but recommended for large windows)
• Pencil and paper or a notepad
• Spirit level (required when checking whether your window frame is square)
• Step ladder or stool (required for windows above a comfortable standing height)
• Smartphone (useful for photographing the window and noting measurements)
• A helper (strongly recommended for large, tall, or difficult-to-reach windows)

Why does the guide recommend a helper?

For large, awkward, or high windows, a second person holds the tape measure in position, reads the figures, and catches errors before they become expensive. It also reduces the risk of working from a ladder without someone steadying it. This is not a suggestion; for any window above two metres in height or spanning more than two metres in width, a helper is the sensible approach.

What Should You Check Before You Take Any Measurements?

Rushing straight to measuring without checking the window environment first is where many customers go wrong. Before you extend the tape measure, work through this checklist:

What obstructions might affect the blind's operation?

Walk to each window and look carefully for the following:

• Window handles and locking mechanisms that project into the recess
• Trickle vents along the frame top or sides
• Tiles on window sills or surrounding walls that reduce the recess depth
• Radiators positioned directly beneath the window
• Light switches or sockets on the wall adjacent to where a control chain would hang
• Restricted wall or ceiling clearance above the window that limits how brackets can be fixed

Each of these obstructions can affect which blind type is suitable, which fitting method is appropriate, and whether your blind will open and close without catching. Identifying them now saves you from discovering the problem after the blind is installed.

Does the condition of the window frame matter?

Yes. If the frame is warped, damaged, or significantly out of square, this affects which fitting method is appropriate and how large a deduction you may need when ordering. We cover this in more detail in the recess versus blind size guide.

What Units of Measurement Should You Use?

Does newblinds.co.uk work in millimetres, centimetres, or inches?

You can enter your measurements in millimetres, centimetres, or inches on the website. The important rule is consistency: use the same unit throughout. The most common mistake customers make is switching between units mid-order, for example measuring width in centimetres but entering drop in millimetres.
 

How precise do your measurements need to be?

Measure to the nearest millimetre. When it comes to rounding, the following rule applies: figures from .1 to .4 round down, and figures from .5 to .9 round up. There is no need to round to the nearest five millimetres or centimetre.

How Many Times Should You Measure Each Window?

Measure every dimension at least twice. If the two measurements differ, take a third and identify which reading is consistent. Never trust a single measurement on a made-to-measure order.

For recess fitting, you will need three width measurements — taken at the top, middle, and bottom of the recess — and two drop measurements, taken at the left and right sides. Always enter the smallest of each set of measurements. This ensures the blind fits within the space without catching.

Should you photograph the window before ordering?

Yes. Photographs serve two purposes: they give you a visual record of obstructions, frame condition, and the window's general proportions, and they can be included in any email to our team if you need advice before placing an order. Clear photographs, combined with written measurements, allow us to give you far more specific guidance.

What Is the Single Most Common Measuring Mistake?

The most frequent error we see is customers entering measurements in a different unit to the one they measured in. For example, measuring in millimetres but entering the figure into a centimetre field on the website. The result is a blind that is ten times too small or too large to be usable.

Double-check that the unit selector on the website matches the unit you measured in before you confirm your order.

Can You Send Your Measurements to newblinds.co.uk for Checking Before You Order?

We do not offer a formal pre-order measurement verification service. However, if you have any doubts, you are welcome to email a screenshot of your basket to customer.services@newblinds.co.uk and a member of the team will be able to advise. For complex, non-standard, or unusually sized windows, email estimates@newblinds.co.uk with your measurements, photographs, preferred blind type, control method, and fabric requirements.

Does newblinds.co.uk Provide Measuring Guides and Videos?

A general measuring overview is available at newblinds.co.uk/measuring-your-window-for-blinds. Some individual product types have their own specific measuring instructions and video tutorials. These are detailed within the relevant product pages and in the product-specific guides within this expert hub.