How to Read a Sewing Pattern: Symbols, Sizing and Seam Allowance

By Colibri Sewing | Sewing & Quilting Supplies | Published: 2026-10-15

Category: How-to Guides

Learn how to read a sewing pattern with confidence. This guide covers the envelope, pattern symbols, sizing, and seam allowance for beginners.

Quick answer

To read a sewing pattern, start with the envelope to confirm size and fabric needs, then unfold the tissue to locate the cutting lines and symbols. Choose your size based on your body measurements, not your ready-to-wear size, and always check the seam allowance included in the pattern before you cut.

Start with the pattern envelope, not the tissue

The envelope is your roadmap. On the back, you'll find a size chart, fabric requirements, and a list of notions like interfacing or buttons. The front shows design variations and views. Before you open the tissue, confirm the pattern includes the size you need and that you have the right fabric width and yardage. If the pattern is multi-sized, the envelope will show a range; circle your size on the chart so you don't lose track.

Decode the symbols on the tissue

Pattern symbols are a universal language. The grainline arrow tells you how to align the pattern with the fabric's selvage to prevent twisting. Notches are small triangles or lines that help you match pieces during sewing. Dots and squares mark placement for pockets, darts, or buttons. A large bracket or line with 'place on fold' means the pattern piece should be positioned on the folded edge of the fabric. If you see a symbol you don't recognize, check the pattern's instruction sheet—most include a symbol key.

Choose your size by measurement, not habit

Sewing pattern sizing is not the same as ready-to-wear. Take your bust, waist, and hip measurements, then compare them to the pattern's size chart. If you fall between sizes, choose the size that matches your bust for tops or your hips for skirts and pants, then adjust the other areas. Many patterns include finished garment measurements, which tell you how much ease is built in. If you're unsure, make a muslin test garment in a similar fabric to check the fit before cutting your final fabric.

Check the seam allowance before you cut

Seam allowance is the distance between the stitching line and the raw edge of the fabric. Most commercial patterns include a 5/8-inch seam allowance, but some independent patterns use 3/8 inch or 1/4 inch. The pattern instructions will state the included seam allowance. If your pattern does not include seam allowance, you must add it to each pattern piece before cutting. Use a ruler and chalk to mark the additional allowance. For curves, a smaller seam allowance like 1/4 inch can make sewing easier, but always follow the pattern's recommendation.

Step-by-step: How to read a pattern from envelope to first stitch

Check the envelope for size and fabric: Measure your bust, waist, and hips. Compare to the size chart on the back. Note the fabric type, width, and yardage required for your view. Common mistake: buying fabric before checking if the pattern needs a nap layout or directional print. Checkpoint: You have the right size and enough fabric.
Unfold the tissue and find the instruction sheet: Locate the symbol key on the instruction sheet. Identify the pattern pieces you need for your view. Common mistake: cutting out all sizes at once; instead, trace your size onto tracing paper or use a rotary cutter with a mat to preserve other sizes. Checkpoint: You know which pieces to cut.
Identify key symbols on each piece: Look for grainline arrows, notches, dots, and 'place on fold' markings. Grainline must run parallel to the selvage. Notches help match seams. Common mistake: ignoring grainline, which causes twisting. Checkpoint: Each piece is oriented correctly on the fabric.
Confirm seam allowance: Read the pattern instructions to see if seam allowance is included and what width. If not included, add it to every piece before cutting. Common mistake: assuming 5/8 inch is always included; independent patterns often use 3/8 inch or 1/4 inch. Checkpoint: You know your seam allowance width.
Cut and mark your fabric: Cut along the correct size line. Transfer pattern markings (notches, dots, darts) to the fabric using chalk, tailor's tacks, or pins. Common mistake: skipping mark transfer, which leads to misaligned seams later. Checkpoint: All markings are visible on the fabric.

Tools that help with pattern reading and sewing

#1 BERNINA Reverse-pattern Foot: #1 BERNINA Reverse-pattern Foot is for forward and reverse-feed stitches and guarantees excellent fabric feed on materials such as cord, denim and wool. When your pattern calls for topstitching or securing seams with reverse stitches, this foot helps maintain even feed on thick fabrics, so your stitching lines stay accurate.
#59C BERNINA Double-Cord Foot 4-6mm: #59C BERNINA Double-Cord Foot 4-6mm is for simultaneously sewing on two parallel cords with a diameter of 4–6 mm, for creating piping, and is for 9 mm machines. If your pattern includes piping or decorative corded details, this foot lets you sew two cords at once, saving time and keeping the cords parallel.