How to Measure for Curtains (Even If You’ve Never Done It Before)

You’ve finally picked out the perfect curtain fabric. Maybe it’s a cheerful floral for the kitchen or a cozy linen for the bedroom. You bring it home, excited to see it hanging, and then it hits you: how on earth do you measure the window? Nobody wants to drop fifty bucks on a set of curtains only to find them puddling on the floor or floating six inches above the sill. The good news is that measuring for curtains is a lot simpler than you think, and once you know a few basic tricks, you’ll never second‑guess yourself again.

Before you grab a tape measure, decide where you want your curtain rod to go. Most people make the mistake of mounting the rod directly above the window frame, but that actually makes your room feel smaller. Instead, aim for a spot about four to six inches above the top of the window trim. If you have a low ceiling, pushing the rod even higher—say, halfway between the top of the window and the ceiling—creates the illusion of taller walls. For windows that sit close to the ceiling, you can mount the rod right at the ceiling line. The same logic applies to the sides: the rod should extend beyond the window frame by at least three to four inches on each side. This way, when you open the curtains, the glass is fully exposed and the room feels wider.

Now for the actual numbers. First, measure the width. Don’t measure the window glass—measure the full width of the window casing, from the outside edge of the left trim to the outside edge of the right trim. Write that number down. Then add your side overhang. If you’re going with the standard three to four inches per side, add six to eight inches total to your window casing width. That final number is the minimum rod length you need. But curtains aren’t just about covering the window; they should look full and gathered. To get that nice, drapey look, you want your curtain panel’s total width to be about two to two and a half times the width of your rod. So if your rod is sixty inches wide, you’ll need panels that add up to 120 to 150 inches of fabric. If you’re using two panels (one per side), each panel should be at least half of that—so roughly sixty to seventy‑five inches wide per panel. If your budget allows, go for the higher end of that range. Thin, skimpy curtains always look like an afterthought.

Next comes the length. This is where most homeowners get tripped up because they think curtains should stop right at the window sill. Actually, the most polished look is to have curtains just barely kiss the floor, or hover a half‑inch above it. For a more casual or romantic vibe, you can let them puddle an inch or two on the floor, but that requires a little extra maintenance and works best in low‑traffic rooms. To measure, start from the top of your rod (not the top of the window) and measure straight down to the floor. If you plan to use curtain rings that clip onto the fabric, measure from the bottom of the ring rather than the top of the rod, because the fabric will hang from the ring’s eye. Add an inch or two if you want a puddle. Write that down.

But wait: curtain panels usually come in standard lengths, like 63, 84, 95, or 108 inches. If your measured length doesn’t match one of those, you have a few options. You can buy longer panels and hem them, or you can adjust your rod height up or down to fit a standard size. For example, if your ideal length is 86 inches, going with 84‑inch panels and a low‑profile rod might work perfectly. Just remember that if you raise the rod, the curtain will hang higher, so you’ll need to recalculate.

One common headache is measuring for windows that are odd shapes—like bay windows, corner windows, or windows above sinks. For a bay window, measure each section of the window separately, as if each were its own little frame. You’ll want a separate rod for each straight section, or you can use a flexible track system. For a window over a kitchen sink, you might want a shorter curtain that stops just below the sill. That’s fine, but still measure from the rod down to where you want the hem, not from the top of the window.

Finally, a tip from every DIYer who has learned the hard way: always double‑check your measurements. Write them down. Measure twice, buy once. And if you’re ordering custom curtains, add an extra few inches to the width to account for seam allowances and pattern matching. Also, keep in mind that sheer curtains often need a little extra fullness—think three times the rod width instead of two—because they’re lighter and don’t hang as heavily as thicker fabrics.

Once you’ve got your numbers, the rest is smooth sailing. You’ll install your rod, slide your curtains on, and step back to admire a room that looks like it was dressed by a professional. And the best part? You did it yourself, saving money and getting exactly the look you wanted. So grab that tape measure, make a cup of coffee, and get measuring. Your windows are ready for their close‑up.