A pattern tells you the shape of each piece, where it sits on the fabric and how much room is built in. You can read most of this on paper before you cut anything.
This lesson is part of the Clothing Design and Sewing section of SPM subjects and learning resources.
What the markings mean
Find these markings before you calculate.
- Cut on fold: the piece is half a shape. Its straight edge goes on the fabric fold.
- Grainline arrow: keep it parallel to the selvedge.
- Seam allowance: extra fabric outside the stitching line. Note its width on the envelope or pattern.
- Hem allowance: extra length at the bottom that turns up.
- Notches and dots: matching points for joining pieces.
The numbers on the pattern are measured to the cutting line, so they include seam allowances unless the pattern says otherwise.
Worked example: a fictional straight skirt
All numbers are invented for practice. The pattern pieces are:
- Front: cut 1 on fold, hip width 25 cm, length 59 cm including a 4 cm hem.
- Back: cut 1 on fold, hip width 25 cm, length 59 cm including a 4 cm hem.
- Seam allowance: 1.5 cm at the side seams.
The wearer’s hip measurement is 90 cm.
Finished width. The 25 cm is half the front, and its centre edge is the fold. Only the side seam edge has a seam allowance.
- Half front after sewing: 25 − 1.5 = 23.5 cm.
- Full front: 23.5 × 2 = 47 cm.
- Skirt hip circumference: 47 (front) + 47 (back) = 94 cm.
Ease. 94 − 90 = 4 cm of ease at the hip.
Fabric width. The fabric is 115 cm wide. Folded selvedge to selvedge, the working width is 115 ÷ 2 = 57.5 cm. The front and back are each 25 cm wide, so 25 + 25 = 50 cm fits side by side, leaving 7.5 cm.
Fabric length. The pattern length is 59 cm. Add 10% for straightening the fabric ends and shrinkage:
- 59 × 1.10 = 64.9 cm, which rounds up to 65 cm.
- Round up to the next 10 cm, so buy 0.7 m.
The mistake that costs marks
A common slip is to read the front as 25 cm wide in total. That gives a hip circumference of 25 + 25 = 50 cm, which is smaller than a 90 cm hip, so the garment could not be worn.
| Step | Wrong | Right |
|---|---|---|
| Piece on fold | Full width = 25 cm | Full width after opening = 2 × 25 = 50 cm (before seam allowance) |
| Seam allowance | Forgotten | Subtract 1.5 cm at the side seam |
| Sense check | None | A 50 cm hip is smaller than the 90 cm wearer, so go back and check the fold |
The sense check is quick. The finished hip should be a little above the body measurement, never below it.
Laying out the fabric
Draw a small sketch showing the folded fabric, the two pieces side by side, and the grainline arrows parallel to the edge. Label the fold and the selvedge.
For each piece, ask three questions. Is the fold edge on the fold? Is the grainline parallel to the selvedge? Do all pieces fit within the working width?
Check yourself
A fictional pattern has a front piece cut on fold, hip width 28 cm, with 1.5 cm seam allowance at the side only. The back is the same. The wearer’s hip is 100 cm. Find the finished hip and the ease.
Answer
Half front after sewing: 28 − 1.5 = 26.5 cm. Full front: 26.5 × 2 = 53 cm.
The back is the same, so the finished hip is 53 + 53 = 106 cm.
Ease: 106 − 100 = 6 cm.
What to study next
Read explaining a fabric and construction choice for an original garment plan, then check your written working with the structured-answer self-review tool.
Sewing practice and practical assessment stay with your school. If you want a teacher to check your pattern calculations, see online one-to-one Clothing Design and Sewing tuition.