Measure from the top of the frame to where you want the curtain to end

Start by deciding how long you want your curtains to hang. Most patio door curtains fall into three lengths: to the sill (the bottom edge of the frame), to the floor, or to about half an inch above the floor. Floor-length curtains look formal and block more light; sill-length curtains are easier to walk past without tripping.

Use a metal measuring tape, not a cloth one — cloth stretches and gives false readings. Stand on a stable step stool if you need to reach the top of the frame. Measure from the highest point where you plan to mount the rod (usually 4 to 6 inches above the frame) straight down to your chosen endpoint. Write this number down. Measure in at least two places on the same door, because frames are often slightly uneven.

If you are hanging curtains on both sides of a double patio door, measure each side separately. The left and right frames may not be exactly the same height.

Key Takeaways

  • Measure the height from where your rod will mount (usually 4 to 6 inches above the frame) down to the sill, floor, or halfway point you choose.
  • Measure the width of the door opening itself, then add 8 to 12 inches on each side so the curtain can cover the glass fully when closed.
  • Use a metal tape measure and take measurements in at least two spots, because door frames are often uneven.
  • Write down both the height and width before you shop, and bring these numbers with you or check them against product listings online.

Measure the width so the curtain covers the glass when drawn

The width you need depends on how much of the wall around the door you want to cover. Measure the width of the actual glass or frame opening first. Then decide how far beyond the frame you want the curtain to extend on each side when it is fully closed.

A standard rule is to add 8 to 12 inches total — 4 to 6 inches on each side of the opening. This overlap prevents light from leaking around the edges and makes the door look more finished. If you want maximum light blocking, add up to 12 inches on each side. If wall space is tight, 4 inches per side is the minimum that still covers the gap.

Measure the width at the top, middle, and bottom of the opening. Patio door frames sometimes bow slightly, so the width may differ by an inch or two depending where you measure. Use the widest measurement you find, then add your chosen overlap amount. This ensures the curtain will cover the entire opening even if the frame is not perfectly square.

Account for the rod width and bracket placement

The curtain rod itself takes up space, and where you mount the brackets affects how the curtain hangs. Most standard rods are 1 to 1.5 inches in diameter. If you are using a thicker decorative rod, the curtain will sit further from the wall.

Brackets are usually mounted on the wall or trim, not on the frame itself. Mounting on the wall gives you more flexibility and keeps the curtain away from the moving door. Measure from the wall to where the rod will sit, then add that distance to your width measurement if the rod will extend the curtain further out than you initially planned.

If you are hanging two separate panels (one on each side of the door), measure the width of each panel separately. Each panel should cover from the center of the door to about 4 to 6 inches past the outer edge of the frame.

Choose between single and double panels

A single wide panel covers the entire door and stacks to one side when open. A pair of panels (one on each side) meet in the middle and stack outward. Single panels are simpler to install and work well in tight spaces. Pairs look more formal and give you more control over how much light enters.

For a single panel, your width measurement is the full distance from one side of your desired coverage area to the other. For a pair of panels, divide that total width roughly in half, then add a few inches to each panel so they overlap slightly in the middle when closed.

Double patio doors (two doors side by side) usually work best with two panels, one per door, or four panels if you want a pair on each door. Measure each section separately to account for the vertical divider between the doors.

Record your measurements and check them twice

Write down your height and width measurements on paper or in your phone. Include the date and which door you measured. If you are buying curtains online or at a store, bring these numbers with you or compare them to the product dimensions before you buy.

Before you purchase, measure one more time. Mistakes in measurement are the most common reason curtains do not fit properly. If you measured 84 inches tall but the curtains you found are 96 inches, they will bunch on the floor. If you measured 60 inches wide but bought 48-inch panels, they will not meet in the middle or cover the frame.

Many curtain retailers list dimensions in their product titles or descriptions. Match your measurements to the listed size, not to the name of the product. A "standard" curtain panel may be 84 inches or 96 inches depending on the brand.

Account for shrinkage if you plan to wash the curtains

Most fabric curtains shrink slightly when washed, especially if they are cotton or a cotton blend. If you plan to wash your patio door curtains, add 2 to 4 inches to your height measurement to account for shrinkage. This is less critical for blackout or thermal curtains, which are often made from synthetic materials that shrink less.

Check the care label on the curtains before you buy. If the label says "dry clean only," shrinkage is not a concern. If it says "machine wash," plan for some shrinkage. Hanging curtains slightly longer than your target length gives you room to adjust them after the first wash.

Frequently Asked Questions

Should I measure inside the frame or outside it?

Measure outside the frame. Your rod will mount on the wall or trim above and to the sides of the frame, not inside it. Measuring inside the frame will give you a width that is too small and a height that does not account for the rod placement above the door.

What if my patio door is not a standard size?

Measure it the same way. Write down the exact height and width you need. Many curtain retailers offer custom sizing or a range of lengths and widths. If standard sizes do not match your measurements, look for adjustable rod systems or panels you can hem yourself.

Do I need to account for the curtain rod pocket?

Yes, but only if you are buying a specific rod size. Most curtain panels have a pocket (the sleeve at the top) that fits a standard 1 to 1.5-inch rod. Check the product description to confirm the rod size it accepts. If your rod is thicker or thinner, the curtain may not hang properly.

Can I use the same curtains on both sides of a double patio door?

Only if both sides are the same width and height. Measure each side separately. Many double doors have a center divider that makes each side slightly different. If the measurements match, you can use identical panels. If they differ by more than an inch, buy separate panels for each side.

What is the best length for patio door curtains?

Floor-length (about half an inch above the floor) is the most common choice for patio doors. It looks finished and blocks light effectively. Sill-length (to the bottom of the frame) is practical if you open the door frequently and do not want the curtain in your way. Avoid curtains that drag on the floor, as they collect dust and can get caught in the door.