A curtain rod that droops on one side pulls the entire window treatment off balance. It's one of those things you only notice once the curtains are up — but by then, you've already drilled the holes. The fix is to check the bracket positions before drilling, not after.
Tools and materials for hanging curtain rods
A pencil, a tape measure, wall plugs and screws, a drill, the curtain rod and brackets, and your phone with Spirit Level Online open in the browser.
Step-by-step: hanging the rod straight
Decide the height and width. Curtain rods are typically hung 10–15 cm above the window frame and extend 15–20 cm beyond each side. Mark the position of the first bracket lightly with a pencil.
Mark the second bracket at the same height. Measure horizontally from the first mark to where the second bracket goes. Then measure vertically from the ceiling or floor to confirm both marks are at the same height. Even a 5 mm difference will be visible once the rod is up.
Check the marks with the spirit level. Hold the curtain rod across both pencil marks and lay your phone on top of the rod. Open Spirit Level Online in Surface Mode. The bubble should sit at centre — 0.0°. If it drifts, adjust the lower mark upward until the reading is level.
Mark any centre bracket positions. For rods longer than 150 cm, a centre support bracket prevents sagging. Mark its position at the midpoint between the two outer brackets, at the same height.
Drill and fix the brackets. Once all marks are confirmed level, drill the holes, insert wall plugs, and screw in the brackets.
Final check before hanging curtains. Lay your phone on the mounted rod one more time to verify. Brackets can shift slightly as you tighten screws. Better to catch it now than after the curtains are on.
Tip: Measure from the ceiling, not the floor. Floors are often uneven, especially in older homes. Measuring up from the floor to set curtain rod height can introduce error across the width of a window. Measuring down from the ceiling (which is usually more consistent) gives more reliable equal-height marks on both sides.
Bay windows and angled walls
Bay windows require the rod to follow the angle of the bay, with brackets positioned at each change in direction. Use Spirit Level Online in Wall Mode to check each wall section is vertical before fixing brackets to it — an angled wall that also leans forward or back will affect how the bracket sits.
What if the ceiling isn't straight?
In older homes, ceilings often bow or slope. If your ceiling isn't level, use the spirit level reading as your reference for the rod — not the ceiling line. A rod that's truly level will look straight even if the ceiling above it isn't perfectly flat. Trust the reading over the visual.
For all wall-mounting jobs — shelves, picture frames, TVs, and more — Spirit Level Online works directly in your browser with no app download required.