Creating the perfect environment in your home often comes down to controlling light effectively. While standard curtains offer privacy and decorative appeal, blackout curtains serve a more technical purpose: total light elimination. However, even the highest quality blackout fabric will fail to deliver complete darkness if not measured correctly. This guide explores the crucial differences in measuring techniques for standard versus blackout curtains, with a focus on achieving that elusive 100% light-free environment.
The Fundamental Difference in Approach
When measuring for standard curtains, aesthetic considerations typically drive decisions. For blackout curtains, functionality must take precedence, with specific attention to eliminating every possible path for light infiltration.
Width Measurements: Beyond the Basics
Standard Curtains
For standard curtains, the traditional approach works well:
- Measure the width of your curtain track or pole
- Multiply by 1.5-2x for appropriate fullness
- For pairs, divide this total by two
Blackout Curtains
For truly effective blackout curtains, width measurements require greater precision:
- Measure the width of the window plus an additional 20-25cm minimum on each side
- For optimal results, extend curtains from wall to wall where possible
- Apply a fullness ratio of 2-2.5x minimum to ensure adequate overlap when closed
- For centre-opening pairs, ensure a generous overlap of at least 15cm where curtains meet
Practical Example: For a window that's 120cm wide, standard curtains might extend 10cm each side (140cm total pole width). For blackout curtains, your pole should be at least 160-170cm wide (extending 20-25cm each side), with the actual fabric width being 2-2.5x this measurement.
Length Measurements: Critical Differences
Standard Curtains
For standard curtains, common lengths include:
- Sill length (to the windowsill)
- Below sill (10-15cm below the windowsill)
- Floor length (1-2cm above the floor)
Blackout Curtains
For blackout functionality, length considerations are more technical:
- Measure from at least 15cm above the window recess
- Ceiling-to-floor is ideal for maximum light blocking
- For less than floor length, ensure curtains extend well below the windowsill (15-20cm)
- Consider a "puddling" effect with an extra 3-5cm of fabric resting on the floor to block light from underneath
Installation Height: A Critical Factor
Standard Curtains
Traditional wisdom suggests hanging standard curtains "high and wide" for aesthetic appeal:
- 10-15cm above the window
- 10-15cm beyond window frame on each side
Blackout Curtains
For blackout purposes, these measurements are minimum requirements, not ideals:
- Position tracks/poles at least 15-20cm above the window, with ceiling mounting being optimal
- Use wrap-around tracks or poles that return to the wall at each end
- Consider ceiling-mounted enclosed cassette systems for ultimate light control
- For wall-mounted tracks, use brackets that position the curtain as close to the wall as possible
Special Considerations for Complete Light Elimination
While standard curtains require basic measuring approach, blackout installations need attention to:
1. Pelmets and Valances
- Measure for a pelmet or valance that extends at least 10cm from the wall
- Ensure it covers the entire track/pole plus an additional 5cm on each end
- Depth should accommodate the stacked curtains when open
2. Addressing Light Bleed at Edges
- For side gaps, measure for:
- Return poles/tracks that curve back to walls
- Side channels or magnetic strips (measure exact curtain drop)
- Overlapping layers or side return panels
3. Floor Gap Solutions
- For floor-length curtains, measure for:
- 1-3cm extra length for slight puddling
- Draft excluder attachments at curtain hems
- Weighted hems that ensure constant contact with flooring
Measuring for Multi-Layer Solutions
For total blackout, single-layer solutions rarely suffice. Consider these measurements for layered approaches:
Dual Track/Pole Systems
- Allow 7-10cm spacing between tracks
- Position blackout layer closest to window
- For combined blackout and decorative curtains:
- Inner layer (blackout): Measured for full window coverage plus overlap
- Outer layer (decorative): Can follow standard measuring guidelines
Window Frame-Mounted Solutions
For ultimate light control, measure for:
- Perfect fit blinds within the recess AND
- Wall-to-wall, ceiling-to-floor curtains outside the recess
- Allow appropriate depth for both systems to operate independently
Special Window Configurations
Bay Windows
- Measure each section individually
- Add 15-20cm overlap at corners
- Consider specially designed bay systems with overlapping capability
Following these specialised measuring approaches will ensure that your standard curtains look beautiful while your blackout curtains actually perform the technical function they're designed for – complete light elimination.