What Size Curtain Rod to Choose
To choose the size of a curtain rod, start from the width of the window and add an overhang of 15 to 20 cm on each side: the rod extends 30 to 40 cm beyond the frame in total, so that the open curtain clears the glass. The diameter depends on the weight of the curtain: the heavier the curtain, the thicker and more rigid the rod must be. Mount it 10 to 15 cm from the wall in projection, and above the frame.
The size of the rod determines how the curtain hangs and holds. Kurtens makes made-to-measure curtains to the exact centimetre, to be sized with the right rod.
Length: the measurement that matters most
The length of the rod is not calculated on the window, but around it. The rule: the width of the window plus an overhang of 15 to 20 cm on each side. In practice, the rod extends 30 to 40 cm beyond the frame in total. This overhang matches the space the curtain takes up when pulled back to the side: without it, the open curtain hides part of the glass and darkens the room.
The calculation is simple: rod length = frame width + 2 times the overhang. For a 120 cm window, allow a rod of 150 to 160 cm. For a wide patio door, two curtain panels meet in the centre, but the rod stays in one piece with the same overhang at each end. To take your measurements, see the sizing guide.
Diameter: according to the weight of the curtain
The diameter of the rod is chosen according to the weight of the curtain and the width to span. The heavier and wider the curtain, the thicker the rod must be so it does not sag in the middle.
| Type of curtain | Recommended rod | Why |
|---|---|---|
| Sheer, light curtain | Thin rod | Little load, discreet look |
| Standard curtain | Mid-range rod | Good balance of hold and discretion |
| Heavy or technical curtain | Thick and rigid rod | Supports the weight without sagging |
A dense, lined or technical curtain (thermal, blackout, soundproof) weighs far more than a sheer: it calls for a sturdy rod and closely spaced brackets. For the details on load capacity and wall fixing according to weight, see which rod for a heavy curtain.
Projection: the distance to the wall
Projection is the distance between the wall and the rod. Allow 10 to 15 cm so the curtain falls freely without rubbing against the window sill, the handle or the radiator. Increase this distance if an obstacle sticks out: roller shutter box, protruding radiator, patio door handle. A projection that is too short presses the curtain against the obstacle and breaks the way it hangs.
Telescopic rod: practical but limited
The telescopic rod, which adjusts in length, is practical for small windows and light curtains. But it has a limit: over a wide span, it sags under the weight of a heavy curtain, because it is hollow and adjustable. For a dense or technical curtain on a wide window, choose a solid, rigid rod mounted on fixed brackets. The detail of the telescopic trap is in the guide to rods for heavy curtains.
Making your choice real: the made-to-measure curtain
The right rod is useless without a curtain at the right dimension, and vice versa. The width of the curtain follows from that of the rod, multiplied by a fullness ratio for the pleats; the height, from the rod to the floor. Kurtens makes made-to-measure curtains to the exact centimetre, in a range of colors and fabrics, delivered ready to hang. You give your measurements, the curtain arrives at the right size. To also choose the type of fixing, see the fixings guide, then the Kurtens made-to-measure curtains.
Frequently asked questions
What rod length for a window?
Take the width of the window frame and add 15 to 20 cm on each side, for 30 to 40 cm in total. For a 120 cm window, allow a rod of 150 to 160 cm. This overhang lets the open curtain clear the glass.
How to calculate the length of a curtain rod?
Rod length = frame width + 2 times the overhang (15 to 20 cm per side). The rod is sized on the window plus its side margins, not on the glass alone. A generous overhang visually enlarges the window.
What rod diameter for a heavy curtain?
A heavy, lined or technical curtain calls for a thick, rigid rod on closely spaced brackets, so it does not sag in the middle. The wider the span, the sturdier the rod must be. Avoid thin rods, designed for sheers.
How far from the wall should a curtain rod be mounted?
Allow 10 to 15 cm of projection so the curtain falls freely without rubbing against the sill, the handle or the radiator. Increase the distance if a roller shutter box or a protruding radiator sticks out from the wall.
Is a telescopic rod suitable for heavy curtains?
Not over a wide span: hollow and adjustable, it sags under the weight of a heavy or technical curtain. It suits small windows and light curtains. For a dense curtain on a wide window, choose a solid rod on fixed brackets.
A well-sized rod holds the curtain and refines the way it hangs. Have your curtain made at the right size with Kurtens made-to-measure curtains, delivered ready to hang.
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