How to Measure Windows for Curtains: Width, Drop, and Overhang

Updated: May 26, 2026

What You Need Before Measuring

A metal tape measure (fabric tapes stretch — don’t use them)
A pencil and notepad, or your phone to enter values directly
The pole or track already installed — you must measure the actual hardware, not estimate from the window

If the pole or track is not yet installed, decide the placement first (see “Where to Position the Pole” below) before taking measurements.

Step 1: Measure the Pole or Track Width

Measure the full length of the pole or track from bracket to bracket — including any decorative finials if the rings pass inside them.

This is the number you enter as “Pole / Track Width” in the calculator.

Do not measure the window opening. The window opening is almost always narrower than the pole.

Why Poles Should Extend Beyond the Window

Poles that extend beyond the window frame allow the curtains to stack (open) clear of the glass, letting in maximum light. Standard overhangs:

Small windows (up to 36” wide): 6” overhang each side = 12” extra
Medium windows (36”–60”): 8”–10” overhang each side
Large windows (60”+): 10”–12” overhang each side

A 60” window with a 12” total overhang = 72” pole. You measure 72” and enter 72” into the calculator.

Step 2: Decide Drop Style and Where to End

“Drop” = the finished length of the curtain panel from the top of the heading down to the hem bottom.

There are four standard drop styles:

Sill Length

Hem ends level with the windowsill. Clean, practical look for kitchens, bathrooms, and children’s rooms. Measure from heading to sill.

Below Sill (Apron Length)

Hem ends 4–6” below the sill — covers the apron moulding below the window. Casual living room and bedroom option. Measure from heading to apron bottom, then add 4–6”.

Floor Length (Standard)

Hem ends 1” above the floor for clearance. This is the standard for most living rooms and bedrooms. Measure from heading to floor, then subtract 1”.

Measuring tip: Use a plumb bob or hang a weighted thread from the heading position to get an accurate measurement to the floor.

Puddle (Formal)

Fabric pools 6–18” on the floor. Formal look for dining rooms and grand spaces. Measure to floor, then add 6–18” depending on desired puddle depth.

Step 3: Measure from the Heading Position (Not the Pole)

This is the most common measurement mistake.

The heading position is not at the pole itself — it depends on the ring or hook style:

Eyelet rings: The top of the eyelet hole sits on the pole. The fabric hangs below the ring. Measure from the top of the pole (where rings sit) down to your desired hem bottom.
Pencil pleat hooks: The hook clips into the heading tape. Measure from where the hook hangs on the ring — typically 1”–1.5” below the pole.
Track gliders: Measure from the bottom of the glider carrier down to the floor.

Practical approach: Install your pole and rings. Hang a metal tape measure from a ring at the same height as your hooks would hang. Measure down to the floor. That’s your drop.

Step 4: Check Your Numbers

Before entering into the calculator, verify:

Width: Is this the pole width (including overhang), not the window opening width?
Drop: Is this measured from the heading position (not the pole itself)?
Number of panels: Most windows use 2 panels. Narrow windows sometimes use 1.
Drop consistency: If you have multiple windows, are all drops the same, or do some windows sit at different heights?

Where to Position the Pole (If Not Yet Installed)

Height

Mount the pole 4–12” above the window frame. Higher mounting makes windows look taller and rooms feel bigger. In low-ceilinged rooms, mount just 4” above the frame. In rooms with high ceilings, mount closer to the ceiling — even if there’s a large gap above the window.

Width

Mount pole brackets 6–10” beyond the window frame on each side. This allows the curtains to stack fully off the glass when open.

If you’re in a rental or cannot use wall brackets, use a tension rod inside the window recess — but tension rods only support lightweight fabrics.

Common Measuring Mistakes

Mistake 1: Measuring the window opening instead of the pole. Result: Curtains won’t cover the window properly when closed; stacks won’t clear the glass when open.

Mistake 2: Measuring from the pole instead of the heading position. Result: Curtains are 1–2” too short or too long, depending on ring style.

Mistake 3: Measuring to the floor instead of 1” above the floor. Result: Curtains drag on the floor, pick up dirt, and wear out at the hem.

Mistake 4: Not accounting for floor undulation. In older homes, floors are not perfectly level. Measure the drop at both sides of the window and use the shorter measurement to avoid one panel dragging.

Once you have accurate measurements, see Curtain Fabric Yardage Formula to understand how your measurements feed into the fabric calculation — or How to Calculate Curtain Fabric for a Pattern Repeat if your fabric has a repeat.

Once you have the pole width and drop, use the Curtain Fabric Calculator to calculate exact fabric yardage.