How to turn a fashion sketch into a sewing pattern

What a sewing pattern is

A sewing pattern is a set of flat pieces, one for each part of the garment: a front, a back, a sleeve, a collar, a facing. Each piece has a cutting line, a seam allowance inside it, a grainline to lay along the fabric, and notches that show which edges join and where.

When the pieces are cut from fabric and sewn edge to edge, they make the shape in the sketch. Turning a drawing into those pieces is called drafting.

1. Read the sketch

Start by deciding what the garment is and how it is built. What kind of garment is it, and how close does it sit to the body? Where are the seams, the darts and the closure? Is the sleeve set in, raglan or cut in one with the body?

Then write down what the drawing can't show: the back, the pockets, the lining, where it opens. Fashion illustrations stretch the figure, often nine heads tall instead of about seven and a half, so the pattern follows the body's real proportions, not the drawing's.

2. Take the body measurements

A pattern is drafted from the body it will fit: chest or bust, waist, hip, back length, shoulder width, and the lengths the garment needs. Measure the body, not a garment, and measure snugly but without pulling.

The measurements guide shows where to place the tape for each one.

3. Draft the block

Pattern cutters start from a block (also called a sloper): a plain, close-fitting shape for the bodice, skirt, sleeve or trouser, drafted from the measurements. It has no style yet, only the body's shape: its darts, its balance from front to back, an armhole that fits the sleeve.

4. Turn the block into the design

The design is built on the block. Darts are moved or turned into seams, style lines are drawn on, fullness is added for flare or gathers, and collars, cuffs, pockets and facings are drafted to match. Each change keeps the edges that meet the same length.

5. Add ease for the fabric

Ease is the room between the body and the garment. Wearing ease lets you move and breathe; design ease gives the silhouette in the sketch. The fabric changes how much you need: a stiff wool needs more room than a soft jersey, and a stretch knit can be cut smaller than the body.

6. Seam allowances, notches and grain

Add the seam allowance and hems, mark the notches and the grainline, and check that every seam matches its partner. Walk the seams: the side seam of the front against the side seam of the back, the sleeve cap against the armhole. A seam that doesn't match will pucker or not close.

7. Test it in a toile

Before cutting good fabric, sew the pattern in calico or another cheap cloth. This test garment is the toile (a muslin in the US). Try it on, pin out or open what doesn't fit, and carry the changes back to the pattern.

How Styli does it

Drafting by hand takes an experienced pattern cutter hours for a simple garment and much longer for tailoring. Styli does the same steps in minutes:

• Upload the sketch, a drawing or a phone photo of one, and describe what it can't show. The AI reads only the sketch, your description and the material.
• Add the fabric and your measurements. Measurements are never sent to the AI.
• Styli drafts the pattern with its own drafting rules, the same steps as above, and checks that every seam matches, including the sleeve cap and armhole and the collar and neckline.
• Test and adjust. It gives you the toile tests and fixes the pattern when one fails, and you can adjust any piece by the centimetre.
• Print or export for a home printer, a copy shop or a projector, or as DXF for CLO 3D.

It drafts tops, shirts, dresses, skirts, trousers, jumpsuits, jackets, coats, capes and corsets. When a design goes beyond what can be drafted, it drafts the base and says how to build the rest. See every step.