Most measuring guides open the same way. Take the tape, measure in three places, write down the smallest number. Nine listings read on their own product pages open somewhere else. One prints a formula and asks you to apply it before you type anything into the size box. One asks you to take three eighths of an inch off your own measurement, then asks you to add two to four inches instead, for the same window, if the shade goes on the wall rather than in the recess. One is sold in a single finished size, where there is nothing to measure, only something to check.
So knowing how to measure for curtains and shades is not really about the tape. A measurement is worth something only once you know which surface it describes, and that is settled before the tape comes out: by where the covering will sit, by the mechanism inside it, and, for a curtain, by where the rod is going. Get that order wrong and you can measure to the eighth of an inch and still order a size that never fitted. It is one stage of measuring, hanging and installing a window properly, and the stage the other two depend on.
The tape is the last step, not the first
Two Pages sells a linen cotton roman shade that asks for 2 1/2 inches of window depth for a manual inside mount, and 4 inches for the same shade with a motor in it. Same fabric, same merchant, same recess, and an inch and a half between the two requirements. The gap is the headrail, not the cloth.
So the mechanism is a measuring decision before it is a shopping one. A reveal three inches deep takes the manual version and refuses the motorised one: on a shallow frame the choice is made for you, before anyone picks a colour. Refused the recess, the motorised shade sits proud of the frame instead, and its headrail stays visible as a band across the top of the window rather than disappearing into it. The room reads that band as part of the window, so an inch and a half of depth decides how the window looks, not only whether the shade fits.
In the room
Listed at $149.99. starting price in the configurator, quantity counted in panels, made to order; no anchor price shown
Catalogue photo from Two Pages, retrieved 2026-08-22.
It happens one step further out too. The woven wood panel track Two Pages sells for wide openings is ceiling mount only, and asks for 3 1/8 inches of mounting depth. Not window depth. Ceiling depth. If the tape never left the window, that number was never taken.
Depth decides before width does
Depth is also where the merchants stop agreeing. Neutral Curtains recommends a minimum window depth of 2 1/2 inches for its motorised system. Two Pages requires 4 inches for the motorised version of its roman shade. Two verbs, two different risks: one is advice you can weigh, the other is a condition of sale.
The Two Pages woven wood roller shade publishes no inside-mount depth at all. Its page says only that an outside mount carries no depth requirement, which is the honest version of the same information.
A shallow frame does not rule a covering out, then. It relocates it. Below the published minimum the product leaves the recess and goes on the wall, where it is free to be wider and taller than the opening, so the window reads larger than it measures. That is a proportion choice landing in the middle of a measuring session, better made on purpose than discovered afterwards.
Compare the two
Minimum inside mount depth: 2.5 in
This listing does not publish minimum inside mount depth.
Checked 2026-08-22 against what Neutral Curtains, Two Pages publish on their own product pages. Fold & Light runs no tests, so a percentage is always the brand speaking, not us.
Then check your window is a size someone actually makes
Before the tape means anything, the number it gives you has to be one a factory accepts. This is the step most people skip when they measure for window shades and blinds, and it is the cheapest one to run.
The window sizes each listing says it will make
widthlengtha dot is a single stock size, not a range
Two Pages Jawara Linen Cotton Roman Shade Cordless
manual
motorised
manual: 22-46 in wide for 20-70 in long, 47-63 in wide for 20-63 in long; motorised: 24-98 in wide, 24-98 in long
Neutral Curtains Custom Motorized Roman Shade & Blinds
22-98 in wide, 14-119 in long, in eighths of an inch
Half Price Drapes Millstone Grey Solid Cotton Room Darkening Tie-Up Window Shade
one ready-made size, 46 in wide x 63 in long
Half Price Drapes Double Layered Extra Wide Sheer Curtain (White)
100W x 84L / 96L / 108L / 120L; a single width
Two Pages Lay Natural Woven Wood Panel Track Blinds – Beige
not published: this listing does not say which window sizes it makes
no size range published on this page
Two Pages Rae Natural Jute Woven Wood Roller Shades Cordless
not published: this listing does not say which window sizes it makes
no size range published on this page
Two Pages Lark Motorized Curtain Tracks
not published: this listing does not say which window sizes it makes
no size range published on this page
Neutral Curtains Extra Wide Bamboo Shade & Blinds | Top Down Bottom Up
not published: this listing does not say which window sizes it makes
no size range published on this page
Neutral Curtains Lily Linen Curtains & Drapes Ripple Fold with Track
not published: this listing does not say which window sizes it makes
no size range published on this page
4 of these 9 listings publish the window sizes they will make. The floor counts as much as the ceiling here: the narrowest width any of them accepts is 22 in, so a window under that is outside the catalogue rather than outside the product. Ranges are shown as published; none is estimated, averaged or borrowed from a neighbouring listing. The 5 silent listings keep their line, and no range is invented for them.
Checked 2026-08-22 against what Half Price Drapes, Neutral Curtains, Two Pages publish on their own product pages. Fold & Light runs no tests, so a percentage is always the brand speaking, not us.
Neutral Curtains publishes size selectors running from 22 to 98 inches wide and 14 to 119 inches long, in eighths of an inch, the kind of range that comes with a made-to-measure price and what it actually covers. Half Price Drapes sells a cotton tie-up shade in one ready-made size, 46 inches wide by 63 inches long, and an extra wide sheer at a fixed 100 inch width. The Two Pages panel track runs from 24 to 102 inches of overall track width.
Read those as floors, not only as ceilings. A window 20 inches across is not too small for a roller shade in any physical sense. It is outside the catalogue, and measuring will not change that.
One listing makes the two axes fight each other. The Two Pages linen cotton roman shade is sold manual at 22 to 46 inches wide for 20 to 70 inches long, and at 47 to 63 inches wide for 20 to 63 inches long. Cross 46 inches of width and the longest available drop falls by seven inches. Seven inches short of the sill leaves a bare band of wall under the shade, on show all day, and the eye reads it as a shade ordered wrong. So on a wide tall window, whether it fits depends on which of the two numbers you settle first, which is a decision rather than a measurement.
The words on the order form are not the same words
Here is the part no tape solves. Every listing asks for a number, and almost none of them asks for the same number.
The words on the order form, and the surface each one names
| What the listing prints | What it names | What it asks of you |
|---|---|---|
| “Inside Mounted: 2 1/2 inches minimum depth requirement”Two Pages · Jawara Linen Cotton Roman Shade Cordless | The reveal, front to back | Measure it first. It rules products out before any width does. |
| “Available in one ready-made size: 46 inches wide by 63 inches long”Half Price Drapes · Millstone Grey Solid Cotton Room Darkening Tie-Up Window Shade | The window sizes the factory accepts | Check your number falls inside the range before you fall for the fabric. |
| “Ordering Dimensions”Two Pages · Lay Natural Woven Wood Panel Track Blinds – Beige | The number you type into the box | The listing has done the conversion for you. Type its result, not your measurement. |
| “Inside Mount: We automatically make a 3/8" deduction …”Neutral Curtains · Extra Wide Bamboo Shade & Blinds | Top Down Bottom Up | The width box, inside mount | Find out who removes it. Removing it twice costs you the width twice. |
| “We recommend ordering additional width (2-4 inches) to prevent light gaps on the sides”Two Pages · Rae Natural Jute Woven Wood Roller Shades Cordless | The width box, outside mount | Here you add. An outside mount is a coverage decision, not a window measurement. |
| “Installation Clearance for Single Track >= 4 inches, Installation Clearance for Double Track >= 7 7/8 inches”Two Pages · Lark Motorized Curtain Tracks | The wall or ceiling above the window | Not a window measurement at all. Measure the free space above the frame. |
| “slight size variations of approximately 0.4 inches may occur”Neutral Curtains · Custom Motorized Roman Shade & Blinds | What the finished size may still move | Read it before you order, not after the parcel arrives. |
| “Stack Height: When fully raised, the shades have a stack height of approximately 7-10 inches”Neutral Curtains · Custom Motorized Roman Shade & Blinds | The glass the raised covering keeps | Comes off the top of the window, every day, in the raised position. |
8 surfaces, 3 brands, every phrase quoted as published. Not one of them says “the window”, and that is the whole difficulty.
Checked 2026-08-22 against what Half Price Drapes, Neutral Curtains, Two Pages publish on their own product pages. Fold & Light runs no tests, so a percentage is always the brand speaking, not us.
Eight published phrases, eight surfaces, and not one of them says “the window”. Track Width asks about hardware. Overall Height counts the track and the panels together. Ordering Dimensions asks for a result you were expected to calculate first.
Put a good measurement in the wrong one and the tape was never the problem: the factory sees a number in a field and cuts to it. Order that panel track on the height of the glass and the track takes its own allowance out of the top, so the panels finish above the sill and leave a line of daylight along the bottom. Nothing about the delivery looks faulty. It hangs short of where the eye expects the fabric to stop.
Who takes the deduction off, you or the factory
Two listings here publish the same three eighths of an inch and mean opposite things by it.
In the room
Inside mount deduction: 3/8 in taken off the measured width on an inside mount by default, cancellable with a note on the order
Catalogue photo from Neutral Curtains, retrieved 2026-09-12.
The Two Pages woven wood roller shade, one of the roller shades we look at across the category, says the order width should be the window casing width minus 3/8 inch. You do the subtraction. Neutral Curtains, on its extra wide bamboo shade, states that it automatically makes a 3/8 inch deduction from your measured width on an inside mount, cancelled by a note on the order. The factory does the subtraction, unless you say otherwise.
The proportion to work to
read it, never assume it
Find out who takes the deduction off
Before you type a width, find the line that says what comes off it. Some listings do the subtraction at the factory; others print your window size minus a fraction and expect you to send the smaller number.
The two instructions look identical on the page and mean opposite things. Subtract when the factory already has, and the covering arrives narrow on both sides, which is exactly where a dark room leaks. Subtract nothing when the listing expected you to, and the covering will not drop into its own recess. The fraction itself is not the decision. Who applies it is.
Trade convention and proportion, not something a merchant told us. A tape measure settles it faster than we can.
Do it yourself on a listing that has already done it and you lose three quarters of an inch of width that nobody meant to remove. It does not show up as a missing dimension. It shows up as a bright line of daylight down both edges of a shade bought for a bedroom, brightest at the hour you wanted it dark. Skip the subtraction on a listing that expected it and the covering will not drop into the recess at all, so the same misreading fails in both directions.
Neither instruction is unreasonable and neither page hides anything. They are two divisions of labour, printed in the same typeface, one screen apart.
Where this figure comes from
Neutral Curtains · Extra Wide Bamboo Shade & Blinds | Top Down Bottom Up
Listed from $65.00
What that covers: lowest base price of six collections (Natural $65.00, Nomi $79.00, Ivy $81.50, Ramie $98.50, Willow $102.00, Hazel $125.00); Total Price = Base Price + Add-ons, so this is not a total
Build your size at Neutral CurtainsThis is an affiliate link: a commission may come back to us, you pay nothing extra for it, and Neutral Curtains charges the same either way. The number above was read on 2026-09-11, so treat the live listing as the figure that counts. The shot beside it is catalogue work by Neutral Curtains, pulled 2026-09-12.
Where this usually goes wrong
| The habit | What it costs | Instead |
|---|---|---|
| Rounding the measurement to be safe The measurement is nudged down a little for clearance, or up a little so nothing is missed, before it goes into the order. | The adjustment lands on top of whatever the listing already does to your number, so the finished size misses twice over, and neither the shop nor the maker has any record of the change. A covering ordered a touch small stays small for its whole life: there is no hem to let out on a headrail. | Send the measurement as taken, to the eighth, and let the listing apply its own deduction. If you think a clearance is needed, ask the merchant for it in writing rather than building it into the number yourself. |
Where this usually breaks down, and the correction. No product figures are involved.
Outside the frame you are not measuring a window at all
An outside mount reverses the arithmetic. The same Two Pages roller shade that wanted three eighths of an inch taken off inside the recess recommends 2 to 4 inches of additional width outside it, to stop light escaping at the sides. Nothing about the window changed. The question did, from “what fits the hole” to “how much do I want covered”, and the second has no single right answer.
Worth considering instead
Tape the outline on the wall before you order
For anything mounted outside the frame, mark the finished rectangle on the wall with low-tack painter's tape, at the height and width you are about to order, and leave it up for a day.
An outside mount is not a window measurement, it is a coverage decision, and a number typed into a box gives you no idea what it will look like. Taped on the wall it takes thirty seconds to see that the width is mean at the edges, or that the header sits too low to lift the window, while the order can still be changed. It also shows you what the covering will hide: a light switch, a trim detail, the top of a radiator.
An arrangement, not a recommendation to buy anything. It works with whatever you already own.
A second number belongs in this decision and rarely gets taken. Whatever the covering does when open, it does somewhere. The Two Pages panel track publishes a panel stack width of 10 1/2 to 36 1/2 inches with three panels, so on a 102 inch opening the stack can hold more than a third of the passage. Neutral Curtains publishes a stack height of approximately 7 to 10 inches on its roman shade, taken off the top of the window every time it is raised.
Both are glass you do not get back. A panel track stacks on the wall if you gave it wall to stack on, and on your glass if you did not; a roman keeps a band of folded fabric across the top of the window all day, so the room reads a slightly shorter window than it has. Measure the opening, then decide where you can afford to lose some of it, sideways or from the top, because one of the two will happen.
Where this figure comes from
Two Pages · Rae Natural Jute Woven Wood Roller Shades Cordless
Listed from $129.98
What that covers: starting price, identical on all 30 colourways, no compare_at. Size entered in the configurator.
Build your size at Two PagesThis is an affiliate link: a commission may come back to us, you pay nothing extra for it, and Two Pages charges the same either way. The number above was read on 2026-08-22, so treat the live listing as the figure that counts. The image above comes from the Two Pages listing, retrieved 2026-09-12.
For curtains, the tape goes on the rod
A curtain has no measurement until the hardware has a position, which is the argument for getting the rod on the wall first. Measure before it is up and the number describes an intention, not a window.
Hardware can also set the number outright. The Two Pages motorised curtain track is sold in three fixed lengths: 122, 200 3/4 and 279 1/2 inches, and its page states that the ordered length includes 4 inches added by the hooks. It asks for 4 inches of installation clearance for a single track, and 7 7/8 inches for a double. None of those is a window measurement. They are questions about the wall and the ceiling, and a window that suits the room can fail all three.
Where this usually goes wrong
| The habit | What it costs | Instead |
|---|---|---|
| Measuring the glass The window is measured pane to pane, and the curtain is ordered to that. | The finished curtain is too narrow and too short, because a curtain is sized from the rod, not from the window: the rod is wider and higher than the glass by design. | Measure the rod path you intend to fit, not the window you are covering. Decide the rod position first, then measure. |
Where this usually breaks down, and the correction. No product figures are involved.
Ready-made curtains reach the same place from the other end. Half Price Drapes sells its extra wide sheer at a fixed 100 inch width, so the question stops being how many inches and becomes how many panels, at what fullness, and which ready-made length to buy. Fullness is what the folds are made of: the same 100 inches reads as a generous pleated panel on a narrow window and as a flat sheet stretched across a wide one. That is counting, not measuring.
Write the number the way the box will read it
Neutral Curtains takes its sizes in eighths of an inch. That is not precision for its own sake, it is the unit the form accepts, and anything rounder gets resolved by someone other than you.
A step that pays off
Write the measurement the way the box will read it
Take each measurement to the nearest eighth of an inch, write it down as a fraction, and send it exactly as taken. No rounding in either direction.
Made-to-measure size fields are built in eighths, so an eighth is not fussy precision, it is the unit the form accepts. Rounding is not caution either: it is a decision you are making on the factory's behalf, usually in the same direction as the deduction it is about to apply. Send what the tape said and let the listing do its own arithmetic.
A practical step, not a product claim. Nothing here depends on which brand you buy.
The same page states that slight size variations of approximately 0.4 inches may occur on the finished shade. Four tenths of an inch is invisible on a wall and perfectly visible as a thread of daylight down the side of a lit window. Read that allowance before ordering, not after unwrapping: it describes what happens after your number leaves you, not what the number should be.
What to ask the listing before you type a number
Four questions, each with a written answer on a good product page.
Does this size box want my window, or my window minus something? If the page does not say, ask in writing and keep the reply.
What is the minimum depth for the mount and the mechanism I want? Manual and motorised are not the same requirement, even on one listing.
What sizes do you make, and does the maximum length change with the width? At least one listing here says yes.
Where does the covering sit when it is open, and how much window does that take? A stack width or a stack height, in inches, is a number a merchant either publishes or does not.
A tape is accurate to an eighth of an inch in anybody’s hands. What it cannot tell you is which of those four answers it is measuring for. That part is reading, and it comes first.
Questions people ask
Do I subtract anything from my window measurement?
It depends on the listing, and the listing says so in writing. Two Pages tells you the order width for its woven wood roller shade should be the window casing width minus 3/8 inch, so you subtract. Neutral Curtains automatically takes 3/8 inch off the measured width of its extra wide bamboo shade on an inside mount, and a note on the order cancels it, so the factory subtracts. Find the sentence before you type. Subtracting by reflex on a listing that already deducts costs you the width twice.
How much depth does an inside mount need?
Only the published figures are worth anything here. The Two Pages linen cotton roman shade asks for 2 1/2 inches of depth in its manual version and 4 inches in its motorised one. Neutral Curtains recommends 2 1/2 inches for its motorised system. The Two Pages panel track asks for 3 1/8 inches of mounting depth, on a ceiling mount. Two listings in this set, the woven wood roller shade and the ripple fold curtain, publish no depth requirement at all, and we are not borrowing a figure from a neighbouring page to fill the gap.
Can I measure for curtains before the rod is up?
No, because the surface to measure is the rod path, not the glass, and it does not exist until the hardware has a position. Hardware can also fix the number for you: the Two Pages motorised curtain track is sold in three fixed lengths, and its page states that the ordered length already includes 4 inches added by the hooks. Decide the rod or track position first, then measure it.