How to Install Blackout Shades? | Straightforward Steps That Work

Installing blackout shades requires three main steps: mounting brackets onto the window frame or wall, clipping the headrail into the brackets, and securing light-blocking tracks for total darkness.

One wrong measurement turns a 30-minute job into a frustrating afternoon of re-drilling holes. The fix is a metal tape measure, a level, and the exact bracket sequence that the blind manufacturers themselves use. Most blackout shades — cellular, roller, or no-drill — follow the same mount-and-clip logic, with one extra track step for cellular models that need zero light leakage.

Tools Needed for Installing Blackout Shades

You probably own most of these already. The drill bit size matters, though — skipping the pilot hole is the most common mistake that cracks window trim.

• Measuring tape — metal tape preferred because cloth tapes stretch
• Cordless drill with a ¼-inch hex or Phillips-head bit
• 1/8-inch drill bit for pilot holes
• Pencil for marking screw positions
• Level — a 6-inch or 12-inch bubble level works fine
• Flat-head screwdriver (needed to release brackets later if you mess up)
• A second pair of hands is helpful but not mandatory for standard-width shades

Which Mount Type Fits Your Window?

Inside mount and outside mount are the only two options, and one of them won’t work for every window. Here’s how to pick before you drill.

Inside Mount

The brackets sit flush inside the window recess, with the shade tucked into the frame itself. This looks cleaner and keeps the trim visible, but it requires at least 2–3 inches of flat, unobstructed depth inside the window opening. If your window has handles, cranks, or thick caulk blocking the corners, inside mount won’t lie flat.

Outside Mount

The brackets mount above the window frame, flat against the wall, so the shade covers the entire window opening plus a few inches of wall on each side. This is the only option for windows without a recess — casement windows, sliding doors, or any frame that lacks a flat inner surface. The trade-off: some wall gets covered and the shade hangs in front of the trim rather than inside it.

Key Steps for Installing Blackout Shades

The actual procedure takes about 30 minutes per window for a standard cellular shade, and most of that time is measuring correctly. Here is the order that avoids re-drilling.

Measure the Window Three Times

Use a metal tape and measure the width at the top, middle, and bottom of the window frame. Record the shortest width. Do the same for height — left, center, right — and record the shortest height. Then measure diagonally from upper left to lower right and from upper right to lower left; if those two numbers differ by more than a quarter-inch, the window is out of square and you’ll need to shim one bracket.

Mount the Brackets Level

For an inside mount, hold the bracket in the upper corner of the recess, flush with the frame, and mark the screw holes. For an outside mount, position it above the window, flush with the wall. Pre-drill pilot holes with a 1/8-inch bit — this prevents the trim from splitting. Screw the front hole first, then the two rear holes. Check level between the two brackets before tightening fully.

Clip the Headrail into the Brackets

Insert the bracket’s front clip into the groove at the front of the shade’s headrail, then push the headrail upward and backward until the rear clip snaps into place. You’ll hear a distinct click if the headrail is seated correctly. For cordless or continuous-loop shades, press the locking tab on the back of the bracket to release the headrail later if you need to remove it for track installation.

Install Light-Blocking Tracks (Cellular Shades Only)

This is the step that makes cellular shades truly blackout. Attach the vertical side tracks with the fuzzy pile side facing the window — the fabric side, not the smooth side. Insert the non-fuzzy edge into the bottom rail’s slit and slide it up until it meets the headrail. Mark the track’s position at the top and bottom so both tracks are even. Peel the tape off the magnet on the track, align it with your marks, and press the track onto the side frame. Finally, secure the magnetic strike plate into the side channel about a quarter-inch from the front edge — this holds the shade tight against the frame and blocks the last sliver of light.

If you’re still choosing which model to buy, our tested blackout shades roundup breaks down which cellular, roller, and no-drill options block the most light per dollar.

Secure the Magnetic Strike Plate

Screw the small magnetic strike plate into the side channel about ¼ inch from the front. This draws the shade’s edge magnetically against the channel, eliminating the light gap that most people miss. Without it, the shade looks installed but light still seeps in from the sides.

Test the Shade Operation

Raise and lower the shade fully two times. It should move smoothly without tilting, catching, or rubbing. If one side rises faster than the other, the brackets are slightly out of level — loosen the screws, shift the bracket a hair, re-tighten, and test again.

Final Checklist: What to Verify Before You’re Done

Three things separate a good blackout installation from a light-leaky one. Check these before you put the tools away.

• Level test: Place the level across the headrail. The bubble must sit centered. Even a slight tilt lets light in at the top and makes the shade drift down unevenly.
• Side seal check: Run your finger along the edges of the shade. If you feel a gap, the magnetic strike plate needs adjustment or the side track isn’t seated fully into the bottom rail slit.
• Full-drop test: Lower the shade completely, then squat at eye level with the window. Look for pinpricks of light. Any you see now will be worse at noon when the sun is directly outside.