Expert Guide: How to Measure Windows for North London Shutters and Blinds

When it comes to upgrading your home with elegant plantation shutters or sleek blinds, the first—and most crucial—step is to measure your window openings with absolute accuracy. A millimetre too wide or too narrow can mean the difference between a seamless fit and costly, time-consuming adjustments. At North London Shutters and Blinds, we have spent more than fifteen years hand-crafting made-to-measure solutions for homeowners who demand quality, sustainability, and style. This comprehensive guide walks you through the entire process, from selecting the right tools to avoiding common pitfalls, so you can measure window spaces like a true professional. Whether you are refreshing a single bay or renovating an entire property, follow along to ensure every panel sits flush, every slat glides smoothly, and every room benefits from perfect light control and privacy.

By dedicating a few extra minutes to precise measurements now, you save hours later on installation day. You also eliminate material waste, aligning perfectly with our eco-friendly ethos of reducing our carbon footprint through smarter production and sustainably sourced materials like bamboo shutters. Most importantly, learning to measure window openings accurately gives you confidence to explore bolder colours, richer textures, and advanced motorisation options because you know your base dimensions are spot on. Ready to begin? Grab your steel tape, sharpen your pencil, and let’s dive in.

Why Accurate Window Measurement Matters

Before you pick fabrics, finishes, or louvre sizes, you must first measure window dimensions with precision. Correct numbers ensure your bespoke shutters not only look custom but perform better—sealing draughts, blocking light, and enhancing energy efficiency. Poor readings lead to gaps that let in unwanted heat, cold, or sunlight, forcing you to rely on artificial climate control and increasing energy bills. By taking time to measure window recesses correctly, you extend the life of your investment, protect your interior décor from UV damage, and enjoy a quieter, cosier living space. Simply put, accurate measurement is the foundation upon which every other design decision stands.

Step-by-Step to Measure Windows Correctly

Follow the sequence below to measure window recesses and frames flawlessly. Consistency is key—always use the same steel tape and hold it level on every pass.

1. Record width in three places. Place the tape at the top, middle, and bottom of the recess. Jot down the smallest figure; this is the width our craftsmen will use.
2. Record height in three places. Again, measure window height on the left, centre, and right. The shortest reading prevents panels from scraping the sill.
3. Check for square. Measure the diagonals from top left to bottom right and top right to bottom left. If the numbers vary by more than 5 mm, note it so we can fine-tune frame tolerances.
4. Depth assessment. A deep recess allows for hidden hinges and tilt rods. Use the tape to measure window depth and confirm there’s enough room for your chosen hardware.
5. Obstruction audit. Radiators, handles, and alarm sensors can interfere with louvres. Carefully measure window distance to these obstacles and provide clear photos during your design consultation.

Repeat the sequence for every opening in the room. Consistent labelling—such as Kitchen-Left or Bedroom-Bay-Centre—prevents confusion later when multiple boxes arrive on site. By adopting this structured method, you will measure window sizes with the same rigour our in-house team applies on professional site surveys.

Tools You Need to Measure Windows

You don’t need a toolbox full of gadgets—just a few reliable essentials: a sturdy 5 m steel tape, a sharp pencil, graph paper, a spirit level for awkward bays, and optionally a laser measurer for double-checking large spans. For extra guidance on selecting measurement tools, see this practical shutter-measurement overview.

Inside Mount: How to Measure Window Recess

Inside-mount shutters sit within the existing reveal, creating a clean, built-in look. To achieve this effect you must measure window width and height extremely carefully because the clearance is minimal. Begin by opening the sash fully to clear the tape, then hook the end clip into one corner and draw the tape straight across. Record three widths and choose the narrowest. Next, close the sash and measure window height from the highest point of the sill to the inside edge of the frame head. Note any tiles, bullnose plaster, or protruding architraves that could reduce depth. Finally, measure depth at three levels; if any reading is less than 65 mm, tell our design consultant so we can recommend low-profile frames.

Outside Mount: How to Measure Window Frame

If your openings are out of square or you wish to hide an unattractive architrave, an outside mount may be best. Here, you measure window frame width including the desired overlap—usually 50–70 mm on each side for shutters and 80–100 mm for roller blinds. Then measure window height from the top of the planned header board down to the sill or floor. Remember to allow space for skirting boards or radiators. Use a level to draw a faint guideline on the wall showing where the top of the frame will sit; this visual aid makes it easier to double-check measurements. For bay and bow windows, create a card template to trace angles, then measure window dimensions against that template to ensure the mitres close neatly.