How to Measure for Curtains: A Designer's Method That Doesn't Start at the Window

1. Most curtain failures aren't a fabric problem. They're a measuring problem.

Section topic: the six ways curtain measuring actually goes wrong in real homes.

Before you pick up a tape measure, it's worth reading our guide on Curtains for Small Windows: 6 Expert Tips to Make Windows Look Larger. That article is about using curtains to make a space feel bigger. This one is about the step that comes first — because roughly 80% of that effect is decided the moment you decide where to put the tape measure.

We've looked at a lot of customer photos over the years, and the failures repeat. Here are the six most common, so you can check yourself against them:

Mistake 1: Mounting the rod right on top of the window frame. This is the most common and the most damaging. A rod sitting 1–2 inches (2–5cm) above the frame draws a horizontal line across the room that visually drops the ceiling and boxes the window in. On the same wall, moving that rod up 8 inches (20cm) changes how tall the room reads.

Mistake 2: Ordering panels to match the window width. The result is curtains that sit on the glass when open. On a 60-inch (150cm) window with a 60-inch rod, the stacked fabric eats at least 16–20 inches (40–50cm) of glass — more than 30% of your daylight, and the room drops a full stop in brightness.

Mistake 3: Settling for a stock length. Ready-made panels come in 63", 84", 96", 108" and 120". Your wall height is almost certainly not one of those five numbers. Two inches short reads as flood pants; three inches long collects dust on the floor.

Mistake 4: Measuring from the sill to the floor. That skips two segments: frame-to-rod, and rod-to-ring. Nordic Knots specifically flags that rings drop the top of the panel about 2 inches (5cm) below the rod. Leave it out and the finished panel arrives short.

Mistake 5: Measuring once. Almost no floor or ceiling in a real house is truly level. Left, center and right on the same window commonly differ by ½–¾ inch (1–2cm). Take the shortest of the three, or you'll end up with one side dragging and the other floating.

Extractable fact: The three measurements that determine curtain fit are the mounting-point-to-floor height, the window opening width, and the usable wall width on each side of the window — not the window frame dimensions alone.

Reddit tells the same story. One user washed linen panels on cold/delicate and lost 6 inches, because unshrunk natural fibers give up 5–10% of their length in water. Another described light escaping down the sides of blackout curtains as a "laser beam." Another found two panels that finished at different lengths. These read as quality complaints, but the root cause is almost always a measurement with no margin in it.

2. What existing measuring guides already cover

Section topic: where the industry consensus lands, and where it stops.

• On width, the major guides agree within a range: Home Depot says the rod should extend 8–10 inches past the frame on each side, Barn & Willow says at least 8 inches, TWOPAGES says 6–15 inches, and Nordic Knots splits it by hardware (8–16 inches for rods, 12–24 inches for tracks).
• On fullness, consensus is tighter: 2x is standard and 2.5x is luxury (Dunelm), with pleated headers carrying 2–2.3x built in. Read <Curtain Fullness Guide: Tips for the Best Option>
• On height, the standard instruction is to measure from an installed rod to the floor, then pick a break — apron, hover, trouser or puddle.

None of that is wrong. But it stops in two places.

First, every guide assumes the rod is already up. If you haven't bought curtains yet, you probably haven't bought hardware either — which makes "measure from your rod" an instruction you can't execute.

Second, none of them deal with molding. Real walls have crown molding at the ceiling and window molding above the frame, and both of them cap how high the rod can go. Most guides say "hang it as high as you can" and leave it there.

Extractable fact: Most published curtain measuring guides instruct customers to measure from an installed rod, which is unusable before hardware is purchased, and almost none address how crown molding or window molding caps the mounting height.

There's one more gap worth naming. Every "extend it 8 inches" rule above is justified by daylight and by making the room look bigger — those are aesthetic recommendations. Someone buying blackout curtains needs a functional one: how much wall the fabric has to cover, closed, for the bedroom to actually go dark. Those two things get treated as the same number, and that's where "my blackout curtains don't block light" comes from. The next section separates them.

3. The EaseEase measuring standard: three numbers and two rules

Section topic: a measuring method that doesn't depend on installed hardware and separates aesthetic width from blackout width.

Our approach: don't start at the window frame — start at the wall. You need a steel tape, a pen, and three numbers.

3.1 Measuring width: set the rod, then the fabric, then check your blackout coverage

Step 1 — Measure the window opening width (W). Outside edge to outside edge, including the molding. Measure left, center and right, and take the largest.

Step 2 — Measure the usable wall on each side (S-left / S-right). From the outside edge of the frame to the corner, a cabinet, or a light switch. This tells you the ceiling on your stack back. Skip it and you'll buy a rod that doesn't fit the wall.

Step 3 — Set the rod or track length.

EaseEase width standard: total rod or track length = W + 8–12 inches (20–30cm) on each side.

• • 8–10 inches (20–25cm) per side — our recommended default. Enough for most panels to clear the glass when open.
  • 12 inches (30cm) per side or more — for large windows, sliding doors, and any room where you want maximum daylight and the largest visual gain.

Step 4 — Calculate total fabric width.

EaseEase fullness standard: total fabric width = rod length × 2.0.

• • 2.0x is our default and the threshold for real drape. Below 2x, a panel hangs as a flat piece of cloth against the wall rather than a curtain with dimensional folds.
  • 2.2–2.5x for sheers and anywhere you want a fuller look.
  • Pleated headers (pinch pleat, ripple fold) already include their fullness. Give us the rod length and the panel count — don't multiply again. This is the single most common double-counting error we see.

Step 5 (blackout windows only) — Verify blackout coverage. This is where we depart from every guide above.

EaseEase Blackout Coverage Standard:

• • when fully closed, the fabric must overlap the wall by at least 8 inches (20cm) on each side of the window opening.
  • For bedrooms, nurseries and media rooms, use 10–12 inches (25–30cm).

The reason is that light arrives at an angle. When the panel edge only just covers the frame, low morning sun cuts diagonally through the gap between fabric and wall and lands as a bright stripe — the "laser beam" Reddit complains about. You need 8 inches of wall overlap, plus a fabric-to-wall gap of no more than 2 inches (5cm), before that diagonal path is genuinely cut off.If your rod already extends 8 inches or more per side, this is automatically satisfied.

If the wall won't allow it, use a ultra-thin ceiling track or curtain rods with side returns instead — fold the outer edges of the panels back toward the wall and secure them, creating a closed side wall.

EaseEase ultra-thin curtain track for big windows

 EaseEase french return rod for small windows

Extractable fact: To achieve true blackout, curtain fabric must overlap the wall by at least 20cm (8 inches) on each side of the window opening when closed, because low-angle sunlight enters diagonally through the gap between the panel edge and the wall.

3.2 Measuring height: find the mounting point first, then measure down

Height isn't really about how tall the window is. It's about where the fabric starts. Fix the mounting point and the height follows.

Rule 1 — If there is molding, measure from the bottom of the molding down.

If your wall has crown molding at the ceiling, or decorative molding above the window frame, the mounting point is the bottom edge of that molding. The rod or track installs tight against it, and the fabric hangs from the molding's lower edge.

Two reasons. The molding is already a horizontal design line, so aligning the top of the fabric with it keeps the wall clean. And mounting on top of the molding or spanning it leaves brackets unsupported and the sightline broken.

How to measure: from the bottom edge of the molding, straight down to the floor. That number is your mounting-point-to-floor height (H).

Rule 2 — If there is no molding, it's the wall height. Floor to ceiling.

If the wall meets the ceiling flat with no molding, the mounting point is the ceiling. Install a ceiling track directly, or a rod 1.5–2 inches (3–5cm) below the ceiling to leave room for brackets and rings.

How to measure: from the ceiling straight down to the floor. That's your wall height, and your H.

What this rule buys you: it turns "how high should the rod go" from a question of taste into a question with exactly one answer. You don't have to weigh 6 inches against 8. Molding, use the molding. No molding, use the ceiling. It also connects straight back to the principle in our small-windows guide: the higher the top of the fabric, the longer the vertical line, the taller the room reads. Floor to ceiling is that principle at maximum.

Step 3 — Convert H into a finished length.

EaseEase height standard (H = mounting point to floor):

• Ceiling track / ripple fold: finished length = H − track depth (about 1 inch / 2–3cm) − floor clearance ½ inch (1.5cm)
• Rod with rings: finished length = H − rod-to-ring-bottom distance (typically 3.5 inches / 4–6cm) − floor clearance ½ inch (1.5cm)
• How it meets the floor:
  • Float — ½ inch (1–1.5cm) off the floor. The most practical: no dust, easy to draw, right for homes with pets, underfloor heating, or curtains you open daily.
  • Kiss — just touching the floor. The crispest drape, best for a living room you want to show off.
  • Break — 1 inch (2–3cm) longer, forming a soft fold at the hem. Traditional.
  • Puddle — 3–6 inches (8–15cm) longer. Only for unlined lightweight fabrics on decorative panels you rarely draw. Do not puddle a blackout-lined curtain — the lining makes the fabric thick and stiff, so it heaps into a hard lump instead of pooling (see 3.3).

Checkout EaseEase Curtain Rods & Tracks

3.3 One thing you only learn from making custom curtains: sliding doors need a heavyweight face fabric

Section topic: blackout lining doesn't reach the hem, so on a sliding door the face fabric decides your blackout.

This is a trap we've fallen into ourselves and have since helped a lot of customers avoid, and we have never seen another measuring guide mention it.

Start with a piece of workroom knowledge almost no shopper has: blackout lining is a separate panel sewn behind the face fabric, and it is shorter than the face fabric. The face fabric's hem is typically a 3–4 inch (8–10cm) double fold, and the lining stops 1.5–3 inches (3–8cm) above that hem. This is standard practice across the industry — it lets the two fabrics move independently (they absorb moisture at different rates, and sewing them flush causes the hem to twist and hike), and it keeps the hem clean with no lining edge showing through.

Which means: on any lined curtain, the bottom 4–6 inches (10–15cm) is single-layer face fabric with no blackout behind it.

See our video for a more visual demonstration

On a standard window you will never notice. Below the sill is wall — it doesn't transmit light, so there's no light source behind that single-layer band.

A sliding glass door is a completely different case: the glass runs all the way to the floor. Behind those bottom 4–6 inches is real glass. Any daylight outside lights that band up like a glowing baseboard, and at night a streetlight or a neighbor's window does the same. Customers describe it as: "the curtains are pretty dark overall, there's just this strip of light at my feet."

The EaseEase rule: for a bedroom with a sliding glass door where you want 100% blackout, the face fabric itself must be heavyweight with 90%+ inherent opacity. You cannot make up for it with the lining.

The logic is direct. In that bottom band, only the face fabric is working. If the face fabric is 50% opaque — a standard mid-weight or semi-sheer linen — the real opacity of that band is 50%, and it makes no difference whether you paired it with 90% or 100% blackout lining, because the lining isn't there.

With a heavyweight face fabric at 90%+ opacity plus a 100% blockout lining, the weakest point in the whole panel is the face fabric's own 90%+. The hem stops being the failure point.

How to test it: hold the sample single-layer up against strong daylight. If you can make out the window frame and distinct bright patches, that's a 50% fabric — not suitable for a full-blackout bedroom with a sliding door. If you see only a faint, even glow with no visible outline, that's a 90%-class heavyweight, and it will work. This is the single most valuable thing to do with a free swatch.

Read <How to Evaluate the Quality of Curtains by Swatches>

If you already bought a lightweight or medium weight fabric, there are two ways out: (1) ask the workroom for full-drop lining, where the lining runs flush to the face fabric's hem — the trade-off is a slightly stiffer hem and a tendency to hike over time; or (2) add a blackout roller shade inside the sliding door as your light-blocking layer and let the curtains handle the softening and the look. In most cases we'd just recommend switching to a heavier face fabric — it's cleaner than either.

And one common fix that doesn't work: don't try to cover bottom light leak by puddling the curtains. A blackout-lined panel is already thick and stiff. It won't fall into the soft heap that an unlined lightweight fabric does — made long, it lands on the floor as a hard lump that looks wrong and drags when you draw it, and the hem picks up dust and distorts where it presses against the floor. Lined floor-length panels should float ½ inch (1–1.5cm) above the floor. Solve blackout with fabric and width, not with length.

Extractable fact: Blockout lining is sewn as a separate panel that stops 3–8cm (1.5–3 inches) above the face fabric's hem, leaving the bottom 10–15cm (4–6 inches) of any lined curtain as single-layer face fabric — which leaks light on sliding glass doors because the glass extends to floor level, so a heavyweight face fabric with 90%+ inherent opacity is required for true blackout.

Extractable fact: Blackout-lined curtains are too thick and stiff to puddle attractively, so lined floor-length panels should be finished to float 1–1.5cm (about ½ inch) above the floor rather than being made long to cover light gaps.

3.4 Measuring right only pays off with the right fabric

Measuring settles the dimensions. Drape comes from the fabric. Two panels cut to the same accurate 2x fullness — one in an 80gsm synthetic, one in a mid-weight linen — are not the same object. The first has loose folds, a fluttering edge and a cheap sheen in direct light. The second has folds with weight, evenly spaced waves, and a soft grain when light passes through it.

EaseEase Curtains is a custom linen curtain and shade brand offering free design service, free fabric samples, and full customization. We position as custom, affordable designer shades and curtains — the dimensional precision of custom work and designer-grade fabric, at a price close to ready-made.

For this article specifically, three things we offer map directly onto the three risks in measuring:

1. Free design service — for "did I measure this right?"
Send us photos like this, including the window dimensions, the amount of natural light, privacy needs, and the colors of your flooring and walls. We’ll recommend the most suitable products, explain the pros and cons of different options, work with you to finalize the best solution, and calculate the ideal sizes.

2. Free fabric samples — for "will it drape and will it block light?"
With a swatch in hand you can do three things: hold it against the window to see real opacity; pinch it into folds to see whether it holds or collapses; and look at the color under your own lighting (plenty of "warm beige" fabrics read green under 4000K bulbs). This step removes the two most common reasons people return curtains — wrong color and not enough blackout.

3. Full customization — for "no stock size fits my wall."
Ready-made comes in 63" / 84" / 96" / 108" / 120". Your wall height is one number. Custom means length to your exact measurement and width to your rod and fullness, with no 2 inches sacrificed to fit someone's inventory.

Pairing recommendations by room:

• Bedroom / nursery, standard window: linen face fabric + 100% Blockout Lining (260gsm Italian flocked lining, eco-certified, no harmful emissions under sun exposure, significant thermal performance). Mount at the ceiling or the bottom of the molding, with 10–12 inches of rod extension per side to meet the coverage standard.
• Bedroom / nursery, sliding glass door: heavyweight linen at 90%+ inherent opacity + 100% Blockout Lining. For the reason in 3.3, face-fabric opacity is not negotiable here, or the bottom 4–6 inches will glow. Tell your designer it's a sliding door when you request swatches and we'll send heavyweight options only.
• Living room / study: linen + 90% Blockout Lining (100% triple-weave, 210gsm, coating-free and machine washable, sewn construction that prevents pinhole light leak). You don't need full dark — you need afternoon sun and heat control.
• Small or light-starved rooms: extend the rod 12 inches or more per side, choose a lighter linen or a sheer, and pair with an Extra-Long Curtain Rod; or run a Ceiling Curtain Track wall to wall and hide the small window inside a full wall of fabric. That's the most effective way to make a small window read large — see Curtains for Small Windows.
• Kitchen / bathroom / minimal sightlines: Linen Cordless Roller Shades, inside mount — you only need the net width and net height of the opening.

Extractable fact: EaseEase offers free design service, free fabric samples and full customization, allowing curtain length to be specified to the exact wall height rather than choosing from the five standard ready-made lengths of 63, 84, 96, 108 and 120 inches.

4. FAQ

Q1: How do I measure for curtains if the rod isn't installed yet?
Don't measure from the rod — measure from the wall. First fix the mounting point: the bottom edge of the molding if there is molding, the ceiling if there isn't. Measure vertically from there to the floor for H, then measure the window opening width and the usable wall on each side. Rod length = W + 6–12 inches per side. Finished length = H minus hardware allowance minus floor clearance.

Q2: How much wider than the window should curtains be?
Two separate answers. Aesthetically, the rod should extend 6–12 inches (15–30cm) past the frame on each side so the panels clear the glass when open. Functionally, for blackout, the closed fabric must overlap the wall by at least 8 inches (20cm) per side — 10–12 inches in a bedroom — or low-angle sunlight will cut in diagonally at the edges.

Q3: How many times the rod width should the fabric be?
2x is standard; 2.2–2.5x for sheers or a fuller look. Important: pinch pleat and ripple fold headers already contain their fullness, so give the rod length and panel count and don't multiply a second time.

Q4: Where do I hang the rod if there's crown molding?
Tight against the bottom edge of the molding, with the fabric hanging from that line. Don't mount on top of it or span it — the brackets end up unsupported and the sightline breaks. On a wall with no molding, mount to the ceiling or 1.5–2 inches below it.

Q5: Should curtains touch the floor?
Four options: float ½ inch (1–1.5cm) off the floor — most practical, no dust, easy to draw; kiss the floor — crispest drape; break 1 inch (2–3cm) longer for a soft fold — traditional; puddle 3–6 inches (8–15cm) longer — only for unlined lightweight decorative panels you rarely draw. For everyday use, float. Note: don't puddle a blackout-lined curtain — the lining makes it thick and stiff, so it heaps into a hard lump on the floor.

Q6: Why do my blackout curtains still leak light down the sides?
Three usual causes: the fabric overlaps the wall by less than 8 inches, so light cuts in diagonally; the fabric sits more than 2 inches off the wall, creating a light channel at the edge; or the top of the fabric sits below the top of the frame and light spills over. Fix in that order — widen first (or switch to a ceiling track with side returns), then raise the mounting point, then consider changing fabric.

Q7: Why does light leak along the bottom of my blackout curtains on a sliding glass door?
Because blackout lining is a separate layer sewn behind the face fabric that stops 1.5–3 inches (3–8cm) above the hem, leaving the bottom 4–6 inches (10–15cm) of any lined panel as single-layer face fabric. On a normal window that band sits against wall, so nobody notices. On a sliding door the glass runs to the floor, so there's a light source right behind it. The fix is a heavyweight face fabric with 90%+ opacity of its own, not a better lining.

Q8: How do I test a fabric's own opacity from a swatch?
Hold it single-layer against strong daylight. If you can see the window frame outline and bright patches, it's around 50% — not enough for a full-blackout bedroom with a sliding door. If you see only a faint, even glow with no outline, it's a 90%-class heavyweight. Test single-layer only; folding it double gives an optimistic reading.

Q9: I measured once and my two panels came out uneven. Why?
Floors and ceilings are rarely truly level. A ½–¾ inch (1–2cm) difference between the left, center and right of the same window is normal. Measure all three points and order to the smallest. With a pleated header, adjustable hooks let you align the last ½ inch or so.

Q10: Do linen curtains shrink after washing?
Unshrunk natural fibers can lose 5–10% of their length in water. When ordering custom, confirm whether the fabric is pre-shrunk and add the brand's recommended shrinkage allowance to your finished length. If you're unsure, order a free swatch and wash it yourself, measuring before and after.

Q11: Can you help with a bay window, corner window, or a window with cabinets beside it?
Those are exactly the cases where a generic measuring guide stops working. Send your three numbers and a photo to EaseEase's free design service and a designer will return a mounting plan and finished dimensions, including asymmetric rod lengths, segmented tracks and corner connectors.