Correctly measuring for curtains is the difference between a window treatment that looks custom-made and one that looks like a mistake. To get that polished, professional finish, you need accurate dimensions before you order.

Follow this step-by-step guide to measuring your windows for curtains, drapes, and rods.

How to measure for drapes diagram

Before You Start: The Golden Rules

  • Use a Metal Tape Measure: Cloth tapes can stretch and cause inaccuracies.
  • Measure in Inches: Round to the nearest 1/8 inch.
  • Measure Each Window: Even windows that look the same size can vary slightly.
  • Decide on Rod Placement First: You cannot measure curtain length until you know where your rod will sit.

1. Determining Curtain Rod Placement

If you don't have a rod installed yet, you need to decide where it will go. This determines the height and width of your curtains.

Rod Width (The Horizontal)

To make your window appear larger and allow maximum light in, extending the rod past the window frame is essential.

  • Standard Look: Extend the rod 3 to 6 inches beyond the frame on each side.
  • Luxurious Look: Extend the rod 8 to 12 inches beyond the frame. This allows the curtains to "stack back" against the wall without covering the glass.

Rod Height (The Vertical)

High placement draws the eye up and makes ceilings feel taller.

  • Standard: Mount the rod 4 to 6 inches above the window frame.
  • High/Modern: Mount the rod closer to the ceiling or crown molding for a dramatic, spacious effect.

2. How to Measure Curtain Width

Common mistake: Buying curtains that match the exact width of the window. This results in curtains that look like a flat sheet when closed. You need "fullness" (waves in the fabric).

Step-by-Step:

  1. Measure the Rod: Measure the total width of your curtain rod (excluding the decorative finials). If you don't have a rod yet, measure the window frame and add your desired extension (usually 6-12 inches total).
  2. Calculate Fullness: Multiply your measured width by a "fullness factor."
    • Standard Fullness (1.5x - 2x): Good for a casual, tailored look.
    • Deluxe Fullness (2.5x - 3x): Essential for a rich, custom-drape appearance.

Example: If your window is 80 inches wide, you need curtains with a combined width of at least 160 inches (2x fullness) for them to look proper when closed.

Curtain width measurement guide

3. How to Measure Curtain Length (Drop)

The "drop" is the distance from the top of the curtain to the floor. Your measuring point depends on your hanging style (grommets, rings, or rod pocket).

Where to Start Measuring:

  • Grommet or Rod Pocket: Measure from the very top of the curtain rod.
  • Rings or Pleats: Measure from the bottom of the curtain ring (the eyelet).

Where to Stop (The Look):

  • The "Kiss" (Float): The curtain hovers less than 1/2 inch above the floor. This is the standard for modern, clean interiors. It hangs straight and stays clean.
  • The "Break": The curtain hits the floor and extends 1-2 inches further. This creates a small bend in the fabric for a tailored, yet relaxed look.
  • The "Puddle": Add 6-10 inches to the length so the fabric pools on the floor. This is best for low-traffic areas and highly formal, romantic aesthetics.

4. How to Measure for Outdoor Curtains

Outdoor measuring follows similar rules but prioritizes durability and cleanliness.

Width

Measure the span of the beam or pergola opening. Like indoor curtains, add 1.5x to 2x fullness if you want them to look substantial when closed. If they are purely decorative stationary panels, standard widths are sufficient.

Length (The Clearance)

Unlike indoor drapes, outdoor curtains should generally not touch the ground.

  • The Hover: Aim for the curtains to end 1 to 2 inches off the ground.
  • Why? This prevents the hem from soaking up rain puddles, collecting patio debris, and wicking moisture that leads to mildew.

Outdoor curtain measurement guide

Summary Checklist

  • Hardware First: Determine rod placement before measuring for fabric.
  • Go Wide: Extend rods 6+ inches past the frame to maximize light.
  • Go High: Mount rods high to make the room feel larger.
  • Add Fullness: Total curtain width should be 2x the rod width.
  • Outdoor Rule: Keep outdoor fabrics 1 inch off the ground to prevent staining.

Frequently Asked Questions

Should curtains touch the floor?

Yes, for indoor curtains. The most popular modern style is for the curtain to hover just 1/4 to 1/2 inch above the floor ("floating"). Short curtains that end at the window sill can make a room look dated and small unless there is a radiator or furniture blocking the way.

How far outside a window should the rod extend?

Ideally, extend the rod 6 to 12 inches past the window frame on each side. This allows the open curtains to rest against the wall rather than blocking the glass, making the window appear significantly wider.

How do I measure for a bay window?

Bay windows require specific hardware. You will usually treat a bay window as three separate measurements. Measure the width of each section individually at the angle breaks. It is often best to use a specialized bay window curtain rod with flexible corner connectors.

What if my measurement falls between standard sizes?

Always round up. It is easy to hem a curtain that is too long, or mount the rod slightly higher to accommodate the length. You cannot fix a curtain that is too short or too narrow.