Roller shades are simple, but a wrong measurement leaves gaps or a shade that won't fit. Pick your mount type first — inside or outside — then measure accordingly.
Inside mount (within the frame):
- Measure the inside width at top, middle and bottom — use the narrowest.
- Measure the inside height at left, centre and right — use the shortest.
- Check frame depth — roller shades need a minimum depth (usually around 1.5–2") for a flush inside mount.
- Don't deduct for clearance; the manufacturer does.
Outside mount (above/over the frame):
- Measure the width you want to cover, overlapping the opening by 1–2" each side for light block.
- Measure from the planned bracket height above the frame down to your desired bottom point.
- Record to the nearest 1/16".
Roller-specific tips.
- The fabric is narrower than the bracket width (the gap is the "fabric deduction") — for an outside mount, size by the bracket coverage you want, not just the glass.
- Note any window cranks or handles that stick out — they can stop a shade from sitting flat.
- Choose opacity (sheer, light-filtering, blackout) before measuring so the mount is right for the fabric.
- For motorized shades, confirm there's room for the motor end and a power route.
Accuracy. Use a metal tape, measure every window, and for a full home book a professional measurement. Bloom Bug builds custom roller shades to your exact size, with DIY shipping across BC and Alberta or installation across the Lower Mainland.