Decision guide

How Long and Wide Should Your Curtains Be?

Measure from the curtain's actual hanging point to the hem position you want, and measure the usable pole or track for width. Then check where the fabric will gather when open. The heading, lining, sill, heating equipment, and floor can change the answer. Use the chosen supplier's measuring instructions to turn those room measurements into an order; window glass alone does not give you the curtain size.

Researched and published Last updated RoomRearrange Editorial Team

Short verdict

What we found

  • Set the fitting position and hem endpoint before choosing a catalog drop.
  • Measure open-curtain storage as well as closed coverage; a wider pole is useful only if the fabric can occupy that space.
  • A render cannot approve curtain dimensions, heating clearances, fixings, or cord safety. Resolve those before ordering.

Method and boundaries

How this guide was built

We inspected the living-room image pair below for the visible curtain edges, window, sill, and heating equipment. Furniture and finishes also change, so curtains are not an isolated variable. The worksheet is an editorial ordering aid. Current IKEA and Dunelm guidance informed the distinction between mounting position, usable fitting width, and heading-dependent drop; CPSC supplies the child-safety boundary.

Review criteria

  • Where the proposed fabric sits relative to the window when open
  • Which objects occupy the space beside and below the opening
  • Whether each worksheet dimension has a named start point and endpoint
  • Which decisions remain unresolved without a product specification or installer

Known limitation

The pair has no scale, curtain specification, fabric sample, hardware details, or closed-curtain view. We have not measured this room or tested its window treatment. Apparent fabric length and fold volume cannot establish an order size, light-blocking performance, heater compatibility, or fixing capacity.

Decision tool

A curtain measurement sheet to fill in before ordering

Copy these rows onto one sheet per window. Use a single unit throughout. Keep room measurements separate from the supplier's final order dimensions, especially when the heading or hardware changes.

RecordWhere to measureWrite downDecision it controls
Opening and side spaceAcross the outside of the window frame; then from each frame edge to the next wall, cabinet, or obstruction.Frame width ___; available wall left ___ / right ___.Where the fitting and gathered fabric can extend. Unequal side space may require an unequal draw.
Usable pole or trackAlong the part on which the curtains travel; exclude decorative pole ends. Record any track overlap separately.Usable width ___; overlap ___; existing or proposed fitting ___.Closed coverage and the width to give the supplier, rather than the glass width.
Stack-backThe space occupied by each curtain when fully open, measured on existing curtains or obtained for the proposed fabric and heading.Stack left ___ / right ___; estimate supplied by ___.Whether the open fabric clears enough glass for your daylight preference. Ask for an estimate if the curtains do not yet exist.
Drop and headingFrom the start point specified for your heading to the chosen hem endpoint, at left, center, and right.Heading ___; start point ___; drops L ___ / C ___ / R ___.The supplier's order drop. Resolve uneven floors before selecting or hemming a panel.
Projection and obstaclesFrom the wall to the outermost handle, sill, blind, or heating equipment; note the window's opening movement.Projection ___; window swing ___; equipment model ___.Bracket depth and the fabric path. Equipment clearances come from its instructions, not from this measurement alone.
Product and fixing detailsRead the curtain and hardware specifications rather than inferring them from a photo.Panel or pair ___; flat or finished width ___; lining ___; support requirements ___.Whether the proposed order and installation match the measured fitting and the wall or ceiling.

Worked examples

Long curtains frame this window, but the closed position is untested

This selected RoomRearrange product example includes an AI-generated proposed direction. It shows a visual relationship between window, curtains, and furniture, not a completed installation, measured fitting test, or customer result.

Living room before redesign with an uncovered dark four-pane window, projecting sill, and heating equipment beneath itBefore
Generated living room direction with pale long curtains open beside the window, new seating, and the heating equipment still beneath the sillProposed direction
Labeled product example

Living room: the fabric parks beside the frame

The proposed pale curtains run down both sides of the dark frame, leaving most of the glass visible in this open view. Their vertical edges give the window wall a different outline. The heater below the sill remains visible between the chairs. Closing these panels would bring fabric across that wall; this image does not show the resulting fabric path or clearance. Check those in the actual room before copying the full-length treatment.

Open the full product example

Preserved

  • ✓ Dark four-pane window on the far wall
  • ✓ Sill and heating-equipment location
  • ✓ Long room envelope
  • ✓ Comparable camera direction

Changed or obscured

  • → Full-length curtains added
  • → Fabric hides parts of the side wall
  • → Seating, rug, and lighting
  • → Closed-curtain position is not shown

Decide what you need when the curtains are open and closed

Stand where you use the room. Do you need privacy while sitting on the sofa, less glare at a desk, or a fabric border around a window you rarely cover? Write down the main job. Decorative side panels and curtains that close every evening are different orders, even when the saved pictures look similar.

Next, open the window and move any nearby furniture as you normally would. Note what occupies the wall beside the frame and the floor below it. A desk against one side can leave nowhere for a thick curtain to gather. You may prefer a shorter curtain or a separately specified blind with decorative side panels, rather than squeezing two full panels into an unsuitable space.

Choose a fitting position you can actually install

Use an existing pole or track if its position and specification suit the new curtains. For a new fitting, mark a proposed line on a room sketch and record its height. IKEA's measuring guide starts with the mounting choice because it affects the curtain length. Raising a pole changes the order drop; it is not a free adjustment after the curtains arrive.

Check the hardware's instructions for wall or ceiling suitability, supports, fixings, and permitted load with the chosen fabric and lining. Get landlord permission for new holes or changes to a supplied fitting. If the mounting surface or concealed services are uncertain, have a qualified installer assess them. A picture cannot identify a fixing that will carry the order.

Separate fitting width, fabric width, and stack-back

These are three different entries. The fitting width is where curtains travel. Fabric width describes the panels before or after gathering, depending on the seller. Stack-back is the space the folded curtains occupy when open. Ask whether a listed width refers to one panel or the pair, and whether it is flat fabric or a finished gathered heading.

Do not apply one fullness multiplier to every product. A ready-made eyelet pair and a made-to-measure pleated curtain may use different ordering conventions. Give the seller the measured fitting width and selected heading, then obtain its required panel width or finished coverage. For a track with returns or an overlap, ask which parts belong in the order measurement.

Before extending a pole, compare available wall space with the proposed stack on each side. Request a stack-back estimate for the actual fabric, lining, and heading. If it will still cover more glass than you want, consider a different fabric or draw arrangement. Extra pole length cannot create wall space where a cupboard already stands.

Measure the drop from the right start point

Name the heading before measuring. Dunelm distinguishes the top of the pole for its eyelet measuring method from the ring eye or track reference for pencil pleats. Other headings and suppliers need their own instructions. Record that start point on the sheet so a second person can reproduce the measurement.

Choose the hem endpoint in the real room: at the sill, below it, or near the floor. Measure left, center, and right to reveal a floor or fitting that is not level. Agree with the supplier how the final drop will handle those differences. If using ready-made curtains, check whether the nearest available length can be altered and what the care instructions require before hemming.

A hem near the floor gives a different outline from one stopping at the sill. Pooling fabric adds a floor-level task: it must be moved for cleaning and kept out of a frequently used route. Try the endpoint with a fabric sample held in place at an accessible height. Pick the version you can live with rather than copying a floor gap from a photograph.

Resolve the heater and cord questions before buying fabric

If there is equipment beneath the window, identify its type and model. Obtain its current instructions and ask the manufacturer or a heating professional to confirm the proposed curtain path in both open and closed positions. Keep that requirement on the measurement sheet. We cannot give a single curtain-to-heater distance for an unidentified unit, including the one in the pictured example.

Where young children live or visit, use CPSC's current Window Covering Cords guidance when selecting a system. CPSC recommends cordless coverings and moving cribs, beds, furniture, and toys away from windows and window-covering cords. Inspect the existing covering as well as the proposed curtains. A pleasing rendering does not verify accessible cords or a child-safe installation.

Take a checked shortlist into the room preview

Handle a fabric sample beside the furniture and window. Check its appearance in daylight and under your lamps, then read its care and lining information. The sample can help you choose color and texture; the specifications and supplier's measuring method still control the order. A screen cannot approve exact color, shrinkage, or light-blocking performance.

For a visual comparison, name the window and equipment that must stay and the fitting line you have measured. Ask to compare your shortlisted hem positions without changing the room proportions. Review the frame and fabric edges first. Once you prefer a direction, return to the completed sheet and get the supplier to confirm the order dimensions before paying.

Continue with the evidence

Checklist to use

Make the next result easier to judge

  1. 1Record the main job: privacy, glare control, closing coverage, or decorative side panels.
  2. 2Fill in frame width, available side space, usable fitting width, and the proposed stack-back on each side.
  3. 3Name the heading and measurement start point; record left, center, and right drops to the chosen endpoint.
  4. 4Check handles, window movement, sill projection, furniture, and the fabric path when open and closed.
  5. 5Identify heating equipment and resolve its instructions with the manufacturer or a professional; choose cordless coverings where young children are present.
  6. 6Confirm installation instructions, wall or ceiling suitability, and any landlord permission before changing hardware.
  7. 7Check a physical sample and care information; have the seller confirm panel count, width convention, and final order drop.

Try the workflow

Start with your real room.

Upload one real room photo, describe what is not working, what must stay, and the direction you want, then review the proposed plan before generating.

Upload your room

Dated sources

Primary references used for factual boundaries

  • Measure the window for curtain rails, curtain rods or blinds — IKEA. Supports choosing the mounting position before calculating length and considering nearby window features. Its suggested dimensions and pleat ratios are not treated as universal rules here. Accessed 2026-10-08.
  • How to measure for curtains — Dunelm. Supports usable pole or track width excluding finials and different drop reference points for eyelet and pencil-pleat headings. Follow the chosen seller's instructions for the actual order. Accessed 2026-10-08.
  • Window Covering Cords — U.S. Consumer Product Safety Commission. Current consumer guidance for cordless coverings where young children are present and keeping furniture, beds, cribs, and toys away from windows and cords. This is not a heater-clearance specification or a summary of local installation law. Accessed 2026-10-08.