How to Measure Windows for Custom Window Treatments
Direct answer: Choose the exact treatment and mount style first, then measure the window in several places with a rigid metal tape. Record the opening, mounting surface, depth, and nearby obstructions without rounding or making your own deductions. Curtains need the planned rod or track position and finished drop; inside-mount shades and blinds need the clear opening; outside-mount treatments need the intended finished coverage. Always enter dimensions according to the instructions for the exact Luxvelum product you order.
Accurate measuring is less about memorizing one formula and more about documenting the real window. A custom treatment is built from the information you submit, so separate the raw measurements from the final order dimensions. If you have not chosen between an inside and outside mount, use our inside-mount versus outside-mount guide before beginning.
Start with the product, mount, and operating plan
A window opening is not a complete specification. A curtain hangs from a rod or track, while a shade or blind may sit inside the opening or cover it from outside. Hardware, controls, handles, trim, and the direction a window moves can all change what must be measured.
Identify the treatment category
Write down whether you are measuring for curtains, a shade, or a blind. Do not transfer an instruction from one category to another. The Luxvelum custom curtain collection and the Luxvelum shades and blinds collection represent different structures and ordering decisions, even when both cover the same window.
Choose inside or outside mount for shades and blinds
An inside mount uses the clear space within the opening. An outside mount attaches beyond the opening and uses a planned coverage area. Decide this before recording order dimensions. If you are uncertain, document both the inside opening and the surrounding wall or trim so the options can be reviewed without another measuring session.
Confirm how the window must operate
Open and close the window. Note locks, cranks, handles, screens, alarm sensors, and trim that project into the treatment area. Also note whether nearby doors, cabinets, furniture, or vents limit where hardware can sit. A measurement that ignores an obstruction may describe the opening correctly but still produce an impractical installation.
Gather a simple measuring kit
Use a rigid metal tape measure, a pencil, and a worksheet or phone note that keeps every window separate. A soft sewing tape can bend or stretch around an edge, which makes repeatable readings harder. If the order form accepts a particular increment, record at least that level of detail and do not round early.
Label every window
Give each opening a location-based name such as “primary bedroom left” or “living room center.” Two windows that look alike can differ. Measure each one independently and keep its width, height, depth, mount choice, and control-side notes together.
Use width by height consistently
Write dimensions as width first, then height. Add the unit beside every entry. Keep raw opening measurements in one column and proposed order dimensions in another. This small separation helps prevent an opening size, finished coverage size, and fabric size from being mistaken for one another.
How to measure for inside-mount shades and blinds
For an inside mount, measure only the clear interior opening where the treatment and hardware would sit. Do not include surrounding trim. The goal is to capture variations in the opening and identify anything that reduces usable space.
Measure width at three positions
Take width readings near the top, through the middle, and near the bottom of the opening. Keep all three readings. Do not assume the sides are parallel, and do not choose a final order width until you have checked the exact product instructions. A product may apply its own manufacturing allowance or ask you to submit dimensions in a particular way.
Measure height at three positions
Measure the clear height on the left, at the center, and on the right. Record each result. A sill, sloped header, or uneven opening can make the readings different. The product instructions, not a universal shortcut, should determine which value becomes the order height.
Record usable depth and obstructions
Measure from the front edge of the opening to the first obstruction, then note the full opening depth separately. Do not count space occupied by handles, trim, a screen, or another projection as usable. Confirm that the exact headrail and brackets can fit before choosing an inside mount. Depth requirements can differ among roller shades, cellular shades, and Venetian blinds.
How to measure for outside-mount shades and blinds
For an outside mount, the opening is a reference point rather than the final size. Measure the area you actually want the treatment to cover and confirm that the planned mounting surface can accept the hardware.
Mark the intended hardware position
Identify where the headrail or brackets would sit: above the opening, on trim, or on another suitable surface. Check for uneven molding and nearby obstacles. Measure the available mounting area as well as the opening so the treatment is not planned where hardware cannot be placed.
Measure the planned finished coverage
Record the total width and height you want the treatment to occupy. Think about edge coverage, trim visibility, sill position, and clearance below the window. Do not automatically add a generic amount to the opening. The appropriate overlap and the meaning of “order width” can vary by product and installation.
Check control and movement clearance
Confirm that a chain, cord, wand, or motorized component would have room to operate without colliding with a handle, wall return, or furniture. Record the preferred control side only if the product offers that choice. Keep operational notes with the dimensions rather than relying on memory at checkout.
How to measure for custom curtains
Curtain measurements begin with the planned hardware and finished look, not only the glass or inside opening. Decide whether a rod or track already exists. If it does not, establish its intended position before measuring the finished width and drop. For a curtain-only worksheet covering hardware span, hanging point, finished drop, panel arrangement, and clearances, use our custom curtain measuring guide.
Measure the rod or track width
For existing hardware, measure the usable span the curtains will cover rather than decorative finials or unrelated projections. For new hardware, mark the intended start and end points and record that planned span. Keep the window-opening width as a separate reference measurement.
Measure from the correct hanging point
The starting point for height depends on the selected header and hardware. Measure from the point where the curtain will actually hang to the intended endpoint. Note whether the desired finish is at the sill, below the sill, or near the floor, but do not invent a clearance or pooling allowance. Confirm the header and length convention on the chosen product before ordering.
Separate finished coverage from panel construction
Record the total area the closed curtains should cover, then follow the product options for panel count, header, and fullness. Fabric behavior and construction vary. Do not treat the raw window width as an automatic panel width, and do not assume every curtain uses the same fullness rule.
Special windows need extra notes
Bay windows, corner windows, French doors, deep sills, and grouped openings add relationships that a single width and height cannot show. Make a simple sketch and label each segment, angle, obstruction, and proposed control side.
Measure grouped openings individually
Record each opening separately even if one long rod, track, or outside-mounted treatment is being considered. Also measure the gaps, trim, and total group span. This preserves both individual and combined options.
Document moving parts
For doors or operable windows, note the swing path, handle position, and any surface that moves. A treatment must be planned around normal operation. Photographs can help explain unusual conditions, but they should supplement labeled measurements rather than replace them.
Common measuring mistakes to avoid
- Measuring before choosing the mount: inside-opening dimensions and outside finished coverage answer different questions.
- Measuring only once: openings can be uneven, so keep readings from several positions.
- Rounding early: preserve the actual readings until the exact order form tells you how dimensions are accepted.
- Making your own deduction: manufacturing allowances and order conventions are product-specific.
- Ignoring hardware and obstructions: depth, handles, trim, controls, and mounting surfaces are part of the fit.
- Copying one window’s numbers: measure every opening, even in the same room.
- Confusing curtain coverage with panel size: record the finished goal first, then use the selected product’s construction options.
Final check before you order
- Match the worksheet label to the correct room and window.
- Confirm the treatment category, exact product, and mount style.
- Recheck width, height, depth, units, hardware position, and obstructions.
- Verify that width is written before height everywhere.
- Compare your raw notes with the product’s current measuring and ordering instructions.
- Review control side, header, panel, and installation choices where applicable.
- Ask for design help before submitting if the opening or order convention remains uncertain.
If you are still selecting a treatment type, the complete guide to custom window treatments explains the practical differences before you measure.
Frequently asked questions
Should I measure the glass or the window frame?
Usually neither measurement alone is enough. Inside-mount shades and blinds use the clear interior opening, while outside mounts use planned finished coverage. Curtains generally use the rod or track position and intended drop. Follow the exact product instructions.
Should I subtract anything for an inside mount?
Do not make an automatic deduction. Record the clear opening accurately and check how the selected product defines order width and manufacturing allowance. Applying a generic deduction can create a second, unintended adjustment.
Can I use the same measurements for matching windows?
No. Label and measure each opening separately. Construction and trim can vary enough that numbers copied from a neighboring window do not describe the actual fit.
What if my three measurements are different?
Keep all three readings and do not hide the variation by averaging. Recheck the measurement, note where the opening changes, and use the exact product guidance to determine the submitted dimension. Ask for help if the fit remains uncertain.
Do curtain measurements work for shades and blinds?
No. Curtains are planned around hardware position, finished coverage, header, and panel construction. Shades and blinds are sized around an inside opening or an outside-mounted coverage area. Use the worksheet and instructions for the category you are ordering.
Measure the window, then follow the product
A reliable order begins with complete raw information: several width and height readings, usable depth, intended hardware position, obstructions, units, and a clear window label. Keep those facts separate from any product-specific order adjustment. That approach makes it easier to compare options, catch inconsistencies, and submit the dimensions the selected Luxvelum treatment actually requires.
