Curtain Lining Calculator

Lining Is the Second Half of Your Curtain Order

By the time you reach the lining, the hard decisions are made. You have picked the face fabric, settled on a heading, and worked out how many widths the curtains take. The lining question that remains is narrower: how much backing fabric do you buy to hang behind the curtains you have already costed. That is what this calculator answers, and it deliberately reuses the width count you arrived at on the face fabric rather than starting from scratch.

The reason it can reuse that number is the way lined curtains are built. The lining is made up to the same number of fabric widths as the face fabric, then locked to the back of the made-up panel and gathered into a single shared heading. If you already have the face yardage from the curtain fabric calculator, the lining is the same widths cut to a different length. The only figures that change are the drop allowances and the absence of any pattern repeat.

How Curtain Lining Yardage Is Worked Out

The calculation runs in two short steps. First it settles the number of widths, exactly as the face calculation does: it multiplies the track width by your fullness ratio, divides by the face fabric width, and rounds up because you cannot buy a part width. A 60-inch track at two times fullness on 54-inch fabric needs two widths per panel, or four widths for a pair. The lining inherits that four.

Second, it sets the lining cut drop. Every width of lining is cut to the finished drop plus a hem, with no separate heading turn because the lining top is folded into the face fabric's own heading. There is no pattern repeat to round up to, since lining is plain. The cut drop is multiplied by the number of widths to give the linear length, which is converted to yards or metres and rounded up to the nearest purchase increment. The same width-count logic drives the general fabric yardage calculator when you are cutting plain rectangles rather than gathered panels.

Why the Lining Is Cut Shorter Than the Face Fabric

Lining is not cut to the same length as the curtain. It finishes about an inch above the bottom hem of the face fabric so that it never shows from the front, and it takes a shallower hem than the curtain does. Where a floor-length curtain might carry a deep double hem and a heading allowance on top, the lining carries only its own hem and nothing at the head. The result is a cut drop several inches shorter than the face fabric's.

This gap is the reason lining and face fabric should be costed separately rather than assuming one figure covers both. On a plain curtain the two totals land close together, but the lining is always a little less. The worked guide to calculating fabric for curtains walks through the face side of the same project so you can see the two numbers side by side.

Interlining: The Layer Between Lining and Face

Interlining is a soft blanket-weight layer sandwiched between the face fabric and the lining. Makers reach for it when a curtain needs to feel substantial: it traps air for insulation, deadens sound, blocks draughts, and gives even a lightweight fabric a heavy, well-fed drape. Curtains built this way are described as interlined rather than merely lined, and the construction sits at the top end of curtain making.

For estimating, interlining behaves like the lining with one change. It is cut to the same number of widths, but to a slightly longer drop because the soft cloth needs a turning allowance and has some give. Toggle it on and the calculator itemises it as a separate material, so your shopping list shows lining and interlining as two distinct lengths to buy. The most common interlinings are these:

• Bump is the heaviest, a thick brushed cotton that gives the fullest, most insulating result.
• Domette is a lighter brushed cloth, a middle weight that adds body without much bulk.
• Sarille is a synthetic alternative that resists shrinkage and sheds less when cut.

All three are cut and counted the same way, so the calculator treats interlining as one material and leaves the choice of weight to you. If you are interlining, buy the same number of widths as your lining and face fabric.

Standard, Blackout, and Thermal Lining

The lining you choose changes the feel of the finished curtain, not the amount you buy. Standard cotton sateen, three-pass blackout, and thermal coated linings are all sold at the same dominant width and use the identical drop-count maths, so the yardage figure does not move when you switch type. What changes is the handling, and it is worth knowing before you cut.

• Standard cotton sateen is the default. It drapes softly, presses well, and is the easiest to sew.
• Blackout carries a coating built up in three passes to stop light. It is heavier and stiffer, so the bottom hem sits firmer and the coated side faces the window.
• Thermal linings add an insulating layer or coating for warmth, and like blackout they are bulkier to turn at the hem.

Because the quantity is the same across all three, you can plan the yardage first and choose the type later. The roman blind fabric calculator applies the same lining logic to flat blinds, where blackout is just as popular for bedrooms.

Is Your Lining Wide Enough?

One check sits outside the yardage figure. Lining is trimmed a little narrower than the joined face panel so that it does not peek past the edges, which means the lining bolt has to be at least as wide as the face fabric for the width count to hold. Most curtain lining is sold at 54 inches, the same as drapery face fabric, so the counts usually match without trouble.

The problem appears when the face fabric is wider than the lining, because a narrower lining then needs an extra width to cover the same panel. Confirm the bolt width before you order, especially on wide face fabrics. Our guide to standard fabric widths lists the common bolt widths so you can check the lining and the face fabric against each other.

Where People Go Wrong

Lining mistakes rarely ruin a curtain on their own, but they cost a return trip to the shop. A few recurring errors account for most of them.

• Cutting the lining to the full curtain length. Lining finishes above the face hem. Cut it to the curtain's finished drop and it will hang below the fabric and show.
• Buying lining to match a wider face fabric width. If the lining bolt is narrower than the face fabric, the width count can rise. Check both widths before ordering.
• Assuming blackout needs more yardage. Blackout uses the same length as standard lining. Budget the quantity, then pick the type.
• Forgetting the interlining is a separate buy. Interlined curtains need a third length of cloth, not extra face fabric. Itemise it so it does not get left off the list.

Treat the lining as its own small project with its own number, and the order becomes routine. Plan the face fabric, plan the lining, add interlining if the curtains call for it, and you leave the shop with everything in one trip.