How to Measure for Curtains
Choose the mounting point and curtain heading first. Measure the intended rod or track width, not only the glass, then measure the drop from the correct hanging reference to your desired endpoint.
Quick answer: Choose the mounting point and curtain heading first. Measure the intended rod or track width, not only the glass, then measure the drop from the correct hanging reference to your desired endpoint. For a conventional outside-mounted rod, IKEA recommends extending the rod at least 15 cm (about 6 in) beyond the window on each side; calculate the finished curtain fabric width separately to allow fullness.
This procedure is for standard residential curtains. Bay windows, motorized tracks, sloping ceilings, Roman blinds, pinch-pleat systems and complex double-track installations need their own system measurements. Do not buy based on a window width alone. Measure twice in the units shown on the product packaging.
Before you begin: safety and materials
What you need:
- Rigid tape measure, notebook and pencil
- Step stool with a safe level footing if needed; avoid overreaching
- Curtain rod or track specifications and curtain heading description
- Helper for wide windows or tall openings
Step-by-step instructions
Step 1: Choose the mounting and endpoint
Decide whether the rod will mount to a wall, ceiling or inside a recess. Note handles, radiators, furniture, window swing and bracket space. Mark your proposed mounting line with removable tape; no drilling is necessary to take measurements.
Step 2: Measure window width and planned rod length
Measure frame-to-frame width. If outside mounting ordinary fabric curtains, add room on both sides: an IKEA recommendation is at least 15 cm each side, where space permits. This is a rod/track planning figure, not a claim that every curtain panel should be 15 cm wider.
Step 3: Work out total fabric width for the desired fullness
Use the actual working pole or track width, excluding finials. As an indicative convention IKEA suggests 1.5–2 times rod width for simple pleats; deeper double pleats may need 2–2.5 times. Check the curtain manufacturer’s published finished-panel width and how the heading gathers; do not assume a labelled 140 cm fabric panel gives 140 cm of finished coverage.
Step 4: Measure the drop from the correct hardware reference
For eyelets or tab tops, follow the panel maker’s reference point on the pole; for hooks and tracks, follow the hook or glider reference. Measure vertically down to the chosen sill, below-sill or floor endpoint. Take left, center and right readings if floor levels vary.
Step 5: Allow for how the curtain will hang and be cleaned
Floor-skimming curtains may need a small gap for cleaning; a puddled style requires extra fabric. Verify finished length and header size, plus any shrinkage instructions before hemming. If curtain washing can shrink the fabric, follow the product maker’s preshrink guidance.
Step 6: Record an order-ready worksheet and recheck
Record frame width, usable rod width, mount type/height, proposed finished panel width, number of panels, measured drop, heading, bracket clearance and units. Verify the selected rod spans the measurement and the chosen curtain set delivers the fullness you calculated.
Practical examples: how the steps change
A 150 cm window in an ordinary room
Using IKEA’s 15 cm-per-side suggestion produces a nominal 180 cm rod span where the wall permits. If choosing 2× fullness, the total flat finished curtain width target is about 360 cm, divided between the panels as sold. This is an illustration, not a universal purchase dimension.
A pole is already installed above uneven flooring
Measure from the installed curtain hanging reference to the finished floor at three positions. Choose the drop according to the shortest clearance if avoiding dragging is critical; check hem and heading adjustments.
Troubleshooting the problems people actually encounter
Curtains fail to meet in the middle: Look at actual finished fabric width, pleat gathering and whether rings or brackets reduce travel; rod length alone does not guarantee coverage.
Panels appear too short: Check whether you started the drop at the pole, eyelet, ring underside or track; each heading uses its own reference.
Curtains hide too much glass when open: Evaluate extension beyond each side and stack-back space before changing fabric width.
A radiator or desk sits below: Choose a deliberate sill or apron endpoint rather than accidentally trapping fabric against a heat source.
Alternatives, product differences and limitations
For recess-mounted tension rods, measure the inside width at the intended height, not the outside-frame width. For ceiling-mounted tracks or layered curtains, use the exact system planning guide, track offsets and bracket requirements. Never infer structural mounting capacity from a curtain-length diagram.
When to stop and seek qualified help
Do not drill or climb unsafely to improve a measurement. If hidden wiring, plumbing, weak plaster or an unknown ceiling substrate makes installation unsafe, involve the appropriate installer.
Frequently asked questions
Are curtain and rod width the same measurement?
No. Rod width controls the span; total panel fabric width usually includes extra material for gathers. Use the finished width on the panel label.
Should I include decorative rod finials?
Normally measure the usable running length between finials for curtain coverage; verify exceptions with the hardware instructions.
Sources & further reading
Use the checklists as you go, and confirm the result before moving on to a more involved repair.