How Much Fabric for a Dress?
The bodice barely matters. Two dresses in the same size can be two yards apart, and almost all of that difference is below the waist.
The Skirt Is the Whole Question
A bodice is a handful of small pieces. Front, back, maybe a facing, maybe sleeves. Change the size and those pieces grow by an inch or two, which is nothing. The skirt is where the fabric goes, and skirt shapes differ enormously.
A straight or lightly shaped skirt is close to a rectangle and cuts efficiently. An A-line flares out, so the hem is wider than the hip and the piece stops nesting neatly with its neighbour. A gathered skirt is a straight rectangle again, just a much longer one, often two or three times the waist measurement. A full circle skirt is in another league entirely and can need more cloth than everything else in the dress put together.
So before looking up any number, answer that question first. It matters far more than your size does.
An A-Line Dress at 45 Inches
Put a size M A-line dress, standard fit, on 45 inch fabric through the sewing calculator and it reports 2 yards of main fabric.
That is with nothing extra: no lining, no interfacing, no pattern to match, and the pieces free to be turned round to pack tightly. It is a realistic floor rather than a typical order, because most real projects break at least one of those conditions. Treat it as the number to start from and add the things your version actually needs.
A One Way Fabric Costs a Quarter More
Change one thing about that dress. Keep the size, the fit, the width and the style, and only say the fabric has a nap or a one way design. The same dress now reports 2.5 yards.
Half a yard, a quarter more fabric, for a decision about the print rather than the dress. It happens because a two way layout can spin a flared skirt piece so its narrow waist end tucks beside another piece’s wide hem. Once every piece has to point the same way, those gaps stay empty and the layout gets longer.
This catches people out with velvet, corduroy, brushed cloth, satin, and any print with a clear top and bottom. Check before you buy by cutting two pieces, turning one, and laying them side by side. The wool guide goes deeper into one way layouts, since almost all wool has this problem.
Your Height Is Not in the Size Chart
Pattern sizes are built around body measurements, and commercial patterns are drafted for one assumed height, often around five foot five or six. If you are noticeably taller or shorter than that, you are going to lengthen or shorten the pattern, and lengthening costs fabric that the envelope figure does not include.
Adding three inches to a skirt sounds small. If that skirt piece sits in a row of its own, you have just added three inches to the total length of the layout, and if it pushes the piece past a point where it stopped fitting beside its neighbour, you may add far more. Work out your adjustments before ordering, not after the pattern is traced.
Lining and Interfacing Are Separate Lines
A lined dress is two dresses worth of cutting, though the lining is usually simpler and often narrower cloth, so it is its own calculation rather than a copy of the first. Interfacing is small pieces but it is a separate purchase, and it comes in its own widths.
Keep them on separate lines with any zip, thread, buttons and bias binding. Adding them into one number is how you end up with plenty of the main fabric and nothing to line it with. If the fabric is silk, the silk guide covers the narrow widths and single layer cutting that come with it.