We measure windows for a living, hundreds of them a year across Los Angeles, and the honest secret is that measuring isn't hard. It's just unforgiving. An eighth of an inch rarely matters; picking the wrong starting point (the window instead of the rod, the frame instead of the opening) throws the whole order. So this guide spends less time on where to hold the tape and more time on the decisions that come before it.
If you'd rather not do any of this, that's a real option too. In LA and Ventura counties, we measure for free, at your home, and the numbers become our responsibility instead of yours.
What you need before you start
A steel tape measure, a pencil, and a sketch. That's the whole kit. Skip the cloth sewing tape; it stretches and sags across wide spans, and wide spans are exactly what you're measuring. If the window is tall, a step stool beats standing on furniture, and a second set of hands makes the long horizontal pulls honest.
Draw each window as a rough rectangle and write the numbers directly on the sketch as you go: width across the frame, height, distance from frame to ceiling, distance from frame to floor. Measure in inches, to the nearest eighth. And measure every window separately, even a matched pair in the same wall. In newer construction they'll agree; in a 1930s Craftsman they can disagree by close to an inch, and the drapes will tell on the builder forever.
The two big decisions before you measure
Every measurement depends on two choices, so make them first.
Inside or outside the frame. Shades can sit inside the window opening (inside mount) or on the wall above it (outside mount). Curtains and drapes are outside-mount by nature; they hang from a rod or track on the wall or ceiling. Inside mount looks clean and tailored and shows off nice trim, but it leaves a small light gap at each edge, and it needs enough frame depth to hold the shade. Outside mount covers the whole opening, blocks light better, and forgives crooked openings.
Where the hem lands. Floor-length is the default for curtains in living spaces; sill-length suits kitchens, baths, and windows over counters or radiators. You don't need the exact hem style yet (kiss, break, and puddle all come below), but you need to know which surface the tape ends at: sill or floor.
How to measure width for outside-mount curtains
Width is rod math, not window math. Work it in three steps.
Step one, size the rod. Measure the outside width of the window frame, then extend the rod 6 to 10 inches past the frame on each side. The extension gives open panels somewhere to stack besides the glass. A drape's stack takes roughly a quarter to a third of the width it covers, so on a wide window, generous extensions keep the view clear when the curtains are open. Before you settle on the number, check what the wall allows: finials add 3 to 6 inches beyond the bracket at each end, and corners, sconces, and switch plates all vote.
Step two, apply fullness. Fullness is the ratio of fabric width to rod width, and it's what separates a custom drape from a flat bedsheet. The number depends on the header style:
| Header style | Typical fullness | The look |
|---|---|---|
| Grommet | 1.5x to 2x | Deep, even columns; modern and relaxed |
| Rod pocket | 2x to 2.5x | Soft, shirred gathers; casual classic |
| Pinch pleat | 2x to 2.5x | Structured, tailored folds from a sewn heading |
| Ripple fold | 2x to 2.2x | Uniform waves on a track; the hotel look |
| Sheers, any header | 2.5x to 3x | Lightweight fabric needs more of itself to read as full |
Step three, split across panels. Total fabric width equals rod length times fullness; divide by the number of panels. A 120 inch rod at 2x fullness needs 240 inches of fabric, so a pair of panels at 120 inches each, or four panels at 60. And if the drapes are decorative only (never drawn), you can drop to stationary panels at around 1.5x and half the fabric cost, which is an honest trade we'll always mention.
The width formula
Rod length = frame width + 12 to 20 in. · Fabric width = rod length × fullness · Panel width = fabric width ÷ number of panels
How to measure width for inside-mount shades
Shades flip the logic: now the opening itself is the measurement. Measure the width of the opening at the top, in the middle, and at the bottom, and record the narrowest of the three. Then measure the height at the left, center, and right, and record the longest. Give the workroom those exact opening numbers; don't subtract anything yourself. Every shade maker takes their own deduction (usually a quarter to three eighths of an inch total) so the shade clears the frame without rubbing, and a double-deducted shade arrives narrow with a light gap you could read by.
Check the depth too. A roller shade wants about 2 inches of flat depth to mount inside; a roman shade with its stacked fabric wants 2 to 3. Plenty of older LA casements simply don't have it, and that's fine: an outside-mount shade on the trim, or drapery over the whole opening, solves it without a remodel.
Bay windows, arches, corners, and French doors
Standard rectangles are the easy 90 percent. The other 10 percent is why measuring guides exist.
Bay windows get measured as three (or five) flat sections, one per plane, plus the two angles between them. A bent bay rod or a ceiling track follows the angles; what matters is the wall width of each plane and where the corners land. Measure each section's frame separately and note the angle as best you can; a phone photo shot from directly above the sill line tells the workroom more than the number does.
Arched windows come down to one honest question: cover the arch or celebrate it? Covering means mounting a straight rod above the arch's peak and measuring length from there, treating the whole thing as a taller rectangle. Celebrating means panels that hang from below the arch, or stationary side panels that frame it. In the Spanish Revival houses of Hancock Park and Silver Lake, the arch is usually the best thing in the room, so we frame it and let the plaster do the talking.
Corner windows need a plan for the meeting point. Two rods dying into the corner leave a light gap unless the panels overlap, so measure each wall's run to the corner and tell the workroom which side should carry the overlap. Mid-century houses in Sherman Oaks and Studio City love this detail, and it's an easy one to get right on the first try.
French doors take either outside-mount panels wide enough to clear the doors completely (measure like a patio slider, stack off the glass) or shallow-projection rods mounted to each door panel itself. For door-mounted, measure the glass, add 2 to 3 inches each side for coverage, and check the handle clearance before committing to a projection.
How to measure length, from sill to puddle
Length is a style decision wearing a measurement's clothes. These are the six hem positions we quote, shortest to longest.
Sill ends level with the window sill; right for kitchens, baths, and anything above a radiator or counter. Cafe covers only the lower half of the glass from a mid-window rod. Float stops a half inch above the floor, hangs dead straight, and never collects dust or dog hair; it's what we recommend for most families. Kiss just touches the floor, the most tailored look, and the least forgiving, since it shows every quarter inch the floor is out of level. Break adds 1 to 2 inches so the hem folds slightly, like a trouser hem on a shoe, relaxed and generous. Puddle adds 6 to 12 inches of fabric pooling on the floor; romantic in a bedroom with linen or silk, and a commitment to re-fluffing it after every vacuum.
Measure from where the fabric actually hangs, not from a guess at the rod. For grommet and rod pocket panels, that's the top of the rod. For pleated panels on rings, it's the eye of the ring, where the drapery pin sits, typically an inch or so below the rod itself. Floors in older houses are honest about their age, so for kiss, break, and puddle lengths, take the height at both ends of the window and the middle, and flag any spread bigger than a half inch.
How high to hang the rod
The standard answer is 4 to 6 inches above the frame, and the better answer is usually higher. Mounting the rod two thirds of the distance between the frame and the ceiling (or to within a few inches of the ceiling in a standard 8 or 9 foot room) pulls the eye up and makes the window read taller than it is. It's the cheapest architectural upgrade in the room.
Two caveats from the field. Crown molding needs about 2 inches of clearance for the bracket, so measure to the molding's bottom edge, not the ceiling. And in the double-height living rooms we see in Beverly Hills and Pacific Palisades remodels, going all the way up can strand the window in a sea of drape; there, we'll usually mount 12 to 18 inches above a 10 foot frame and let the proportions breathe. Tall spaces are also where a professional measure earns its keep; ladders, stacked fabric weight, and 14 foot panel lengths are not a Saturday project.
Hardware, brackets, and the return
The rod needs three numbers: length (from the width step), diameter, and projection. Projection is how far the bracket holds the rod off the wall, usually 3 to 3.5 inches. Layering drapes over an existing shade or blind? Use a 5 to 6 inch projection so the panels clear the inner treatment. The return is the fabric that wraps from the face of the panel back to the wall at each end, closing the side gap; it should match the projection, which is why we ask for it on blackout orders especially.
Fabric logistics live here too. Most decorative fabrics from mills like Kravet and Schumacher run 54 inches wide, so wide panels are seamed from multiple widths, and patterned fabric has to match at every seam across its pattern repeat. None of that math lands on you with a custom order, but it explains why a 25 inch damask repeat quotes higher than a plain linen at the same size.
Common measurement mistakes we catch on custom orders
These five account for nearly every remake we've ever sewn.
- Measuring the window instead of the rod, which produces panels that cover the glass and nothing else. Width is always rod length times fullness.
- Copying the numbers from old curtains. Ready-made panels come in stock sizes that were wrong for the window the day they were bought.
- Assuming identical windows. Measure each one; pre-war LA framing was done by hand, and it shows an inch at a time.
- Forgetting what lives under the window. Baseboard heaters, vents, and deep sills all change the right length, and a floor-length drape over a working radiator is a fire question, not a style question.
- Rounding to the nearest inch. Workrooms sew to the eighth; give them the eighth. "About 84" and "84 and five eighths" are different drapes.
One more, less a mistake than a missed opportunity: not photographing the wall. A quick phone photo of the whole window wall catches the switch plate, the sconce, and the off-center window that a column of numbers never mentions. We ask for photos with every remote order for exactly this reason.
Frequently asked questions
How do I measure windows for curtains?
Start with the decision, not the tape: will the curtains hang outside the frame (almost always yes for curtains) or will a shade sit inside the opening? For outside-mount curtains, measure the frame width, then plan a rod that extends 6 to 10 inches past the frame on each side, and measure from your planned rod height down to where you want the hem. Write down every number to the nearest eighth of an inch and measure every window separately, even the ones that look identical.
How do I measure for curtain rods?
Measure the window frame's outside width, then add 12 to 20 inches total so the panels can stack beside the glass instead of covering it. That extra is the stack space, and it's what makes windows look larger and rooms brighter. Check the wall space on each side before you commit: finials add 3 to 6 inches beyond the brackets, and a light switch or an abutting wall can force a shorter rod on one side.
How do I measure for pinch pleat curtains?
Pinch pleat panels are sewn to a finished width, so the workroom needs your rod length and your fullness target rather than a flat fabric width. At the standard 2x to 2.5x fullness, a 100 inch rod needs about 200 to 250 inches of fabric width across the pair before pleating. For length, pleated panels usually hang from rings, so measure from the eye of the ring (where the drapery pin sits) down to the floor, not from the top of the rod.
How do I measure for grommet curtains?
Grommet panels slide directly onto the rod, and the fabric above the grommet stands about an inch to an inch and a half above it. So measure from the top of the rod to the floor, then the workroom adds that standing header height. Fullness runs lighter with grommets, 1.5x to 2x, because the fabric folds into deep, even columns on its own. Deeper fullness than that and the columns crowd each other.
How do I measure for blackout curtains?
Measure the same way you would for any outside-mount curtain, then be more generous with the overlaps, because every gap leaks light. Run the rod 8 to 10 inches past the frame on each side, plan the rod at least 4 inches above the frame, and take the hem to a kiss or break length rather than floating above the floor. A wraparound (French) return, where the panel curves back to touch the wall, closes the side gaps that flat panels always leave.
How do I measure curtains for a patio door?
Treat a slider like a very wide window with one extra requirement: the panels have to clear the door completely when open. Measure the full door width, then add enough rod on the non-sliding side (or both sides) for the stack, which is roughly 25 to 30 percent of the covered width for a traversing drape. Length should end at a kiss or a half inch float; a break or puddle drags every time someone walks through the door.
How do I measure fabric for curtains?
You don't need to compute yardage yourself when you order custom, but the math helps you understand quotes. Most decorative fabrics come 54 inches wide, so a workroom seams widths together to reach your panel width, then adds 16 to 20 inches per cut for hems and headers. Patterned fabric takes more, because every seam has to land on the same point in the pattern repeat; a 25 inch repeat can add half a yard per width.
How do I measure for cafe curtains?
Cafe curtains cover the lower half of the window, so first pick the rod line, usually at the meeting rail of a double-hung window or just above the midpoint of the glass. Measure from that line down to the sill for the length, and use the frame width plus an inch or two for the rod. They're a kitchen and bathroom classic for a reason: privacy at eye level while daylight keeps coming in over the top.
What if my window is slightly crooked?
Welcome to older Los Angeles housing stock; a 1920s Spanish Revival window that's a half inch out of square is completely normal. For outside-mount curtains it rarely matters, because the rod mounts level to the world and the frame's tilt hides behind the fabric. For inside-mount shades it matters a lot: measure the opening width at the top, middle, and bottom and use the narrowest, and if the numbers differ by more than about three eighths of an inch, switch to an outside mount.
Do I measure the window or the rod for curtain width?
The rod. This is the single most common mix-up we see on self-measured orders: the window's width tells you almost nothing about the panel's width. Panels are sized to cover the rod at your chosen fullness, and the rod is deliberately wider than the window so open curtains stack against the wall instead of the glass. Decide the rod length first, then multiply by fullness, then divide across the number of panels.
Two ways to get it made
However you measure, the sewing happens the same way: cut and sewn to your numbers in our Los Angeles workroom, in fabrics you've held first. What changes is who holds the tape.