How Much Fabric Do I Need for Curtains?

To work out how much fabric you need for curtains, you must know the span to cover, the chosen heading, the fabric’s usable width and the finished drop. You also need allowances for construction and, where relevant, pattern matching. Measuring only the glass and buying that many metres is unlikely to produce a reliable result.

This guide explains the logic so you can understand a quotation and prepare useful measurements. The examples are illustrative planning calculations, not cutting instructions for an unspecified fabric. Have your curtain maker confirm the final quantity before purchasing or cutting, especially for patterned, directional, lined or extra-wide fabric.

Start with five pieces of information

Record the usable track or pole span, the intended finished drop, the number of panels, the heading and the chosen fabric’s width. Also note whether you want one curtain drawing to a side or a pair meeting in the middle. The same opening can require different construction depending on how it will be dressed.

Measure the actual hanging system where possible. A pole measurement normally excludes decorative finials, while the treatment of track overlaps and returns should be agreed with the maker. Follow our window measuring guide to record the opening and surrounding clearances without confusing them with finished curtain sizes.

Understand linear metres, fabric widths and fullness

A linear metre is one metre measured along a roll at its stated width. Buying one linear metre of a 140-centimetre-wide fabric is not the same as buying one square metre. A fabric width, in curtain making, can also mean a vertical strip cut from that roll and joined to other strips to form a panel.

Fullness is the extra fabric arranged into folds across the span. For example, two-times fullness describes fabric width approximately twice the coverage before the folds are formed. The appropriate factor depends on heading and construction. Compare our eyelet and pinch pleat guide before settling on a heading.

The basic planning formula

For conventional curtains made from vertically joined widths, the general estimate is: coverage multiplied by fullness, divided by fabric width, then rounded up to determine the number of widths. Multiply that number by the cutting length per width. Patterned fabric needs additional planning so repeats align. The Just Fabrics fabric calculation guide sets out this general approach.

In a real cutting plan, use the appropriate usable fabric width and account for side hems, joins, overlaps and returns. Do not assume the printed roll width is all available as finished coverage. The maker should decide where allowances enter the calculation and verify the resulting panel widths rather than applying a generic formula blindly.

Worked example: a plain pair of curtains

Imagine a project with a 240-centimetre coverage span, an agreed fullness factor of two and a 230-centimetre finished drop. For this example only, the maker plans with 140-centimetre fabric widths and a combined top-and-bottom allowance of 30 centimetres. These are hypothetical inputs, not standard allowances for every curtain.

The initial width calculation is 240 × 2 = 480 centimetres. Dividing 480 by 140 gives about 3.43 widths, so the estimate rounds up to four widths. A pair could use two widths in each panel, subject to the maker checking finished width after seams and side hems. The cutting length in this example is 230 + 30 = 260 centimetres.

Four cuts of 260 centimetres give 1,040 centimetres, or 10.4 linear metres of face fabric. This is the illustrative base estimate for the whole pair, not 10.4 metres per panel. It excludes any additional allowance needed for the actual fabric, flaws, shrinkage, special construction or purchasing increments. Lining and other materials are separate.

What changes when the fabric has a pattern?

A pattern must line up across joined widths if that is the intended finish. For a simple straight-match example, suppose the required cutting length is 260 centimetres and the vertical repeat is 64 centimetres. Five whole repeats give 320 centimetres; four repeats give only 256 centimetres, which is too short. Four repeat-aligned cuts would therefore total 12.8 metres before any extra starting-position allowance.

That example does not cover every printed fabric. Half-drop designs, horizontal matching, centred motifs, borders and directional patterns can change the layout. Ask for a fabric-specific cutting plan. Keep a record of both the repeat measurement and the match type; the phrase “pattern repeat” on its own may not contain enough information.

Why the finished drop is not the cutting length

The finished drop is the visible height after the curtain is made and hung. The cutting length also has to accommodate the heading and hem construction. Eyelets, pleated headings and other finishes can require different upper arrangements, so do not add the same allowance to every order.

Agree the measuring point and the finished bottom position before the maker calculates the cuts. A curtain that finishes just clear of the floor needs a different specification from one intentionally resting on it. If the floor is uneven, discuss which measurement will control the finished pair rather than averaging the numbers without explanation.

Extra-wide fabric needs a different conversation

Some fabrics are intended to be used across the curtain in a way that avoids the usual vertical joins. This can change what the roll width represents and how the linear quantity is calculated. Do not turn any fabric sideways simply because it appears wide enough: the design direction, weave and manufacturer’s intended use matter.

Tell the maker the exact fabric reference and roll width. Ask whether the fabric will be used in conventional vertical widths or in an approved alternative orientation. A calculation built for one method should not be reused for the other without checking it.

Calculate lining and sheers separately

The decorative face fabric is only one part of a layered treatment. Lining may have a different width, finished length and construction allowance. A separate sheer curtain needs its own span, fullness, drop and heading plan. Adding a second layer does not simply mean doubling the face-fabric number.

For functional choices, read our blackout curtain guide and sheer curtain guide. Once the layers are specified, check that the hardware supports their weight and has enough clearance for both to move.

Avoid costly calculation mistakes

Use one unit consistently throughout the working. Mixing a width in metres with a drop in centimetres creates errors that can be difficult to spot once a total looks plausible. Label every number as coverage, finished size, cutting size or fabric width. Keep the total for a pair separate from the quantity for one panel.

Do not round a required number of widths down to reduce cost without asking whether the resulting construction still works. Equally, do not order a large arbitrary surplus as a substitute for a cutting plan. The objective is an appropriate allowance for the chosen fabric and construction, not simply the smallest or largest number.

Turn the estimate into a useful quotation

Ask the quotation to separate face fabric, lining, making, hardware and installation where applicable. Confirm whether the material price is per linear metre or whether the amount is a finished-panel price. Our curtain price guide explains why matching the quoted scope matters.

Before paying for cut fabric, confirm the reference, colour, batch availability, quantity, repeat and care instructions. If several windows should match, have them planned together. Keep the maker’s approved measurements and cutting specification with the order so there is a shared record of what the quantity is intended to produce.

For help preparing an order, contact Curtains Kenya with your hardware span, preferred drop, heading and fabric choice. You can explore available designs in the curtain collection. Treat an online calculation as a planning tool; the final purchase should follow the confirmed construction details.