Sewing Seam Allowances: The Complete Guide
Seam allowances are included in every sewing pattern. Understanding them—and knowing which brands include them and which don't—prevents costly cutting mistakes.
What Is a Seam Allowance?
A seam allowance is the strip of fabric between the cut edge and the stitching line. When a pattern instructs you to sew two pieces together, you align the edges and stitch along the seam line, which sits inside the cut edge by the seam allowance distance.
For example, a ⅝″ seam allowance means the stitching line runs ⅝ of an inch from the fabric edge. The seam allowance itself gets folded into the seam and is not visible in the finished garment.
Why Seam Allowances Matter
- They provide fabric to stitch into—without them, stitching would pull out of the edge.
- A wider allowance gives more room for fitting adjustments.
- Using the wrong allowance width changes the finished garment size.
- On curved seams (necklines, armholes), allowance width affects how the curve lies flat.
Standard Seam Allowances by Pattern Brand
Always read the pattern instruction sheet—some pieces within a pattern may have different allowances.
| Brand | Seam Allowance | Notes |
|---|---|---|
| Simplicity | ⅝″ (15 mm) | Included on all pattern pieces unless noted otherwise. |
| McCall's | ⅝″ (15 mm) | Included. Same standard as Butterick and Vogue (all McCall Company brands). |
| Butterick | ⅝″ (15 mm) | Included on all pieces. |
| Vogue | ⅝″ (15 mm) | Included. Vogue patterns often have more complex construction; check each piece. |
| Burda Style | None included | Burda patterns are printed WITHOUT seam allowances. Add your own before cutting. |
| Kwik Sew | ¼″ (6 mm) | Uses a narrow ¼″ allowance; designed for knit fabrics and serger construction. |
| New Look | ⅝″ (15 mm) | Included. New Look is a beginner-friendly line from Simplicity. |
Burda Style is the notable exception: their tissue patterns print the stitching line only, so you must draw and cut your own seam allowances.
Seam Allowances by Garment Type
| Garment Type | Typical Seam | Notes |
|---|---|---|
| Woven blouses & tops | ⅝″ | Standard; finish edges to prevent fraying. |
| Trousers & jeans | ⅝″ | Inseam and outseam; crotch curve may need ½″ for ease. |
| Dresses & skirts | ⅝″ | Standard. Hem allowance is typically 1–2″ extra. |
| Jackets & coats | ⅝″–1″ | Wider allowance gives flexibility for fitting adjustments. |
| Knit T-shirts & activewear | ¼″–⅜″ | Narrow; serged or overlocked for stretch. |
| Swimwear & lingerie | ¼″ | Very narrow; stretch stitches or serger required. |
| Quilting blocks | ¼″ | Precise ¼″ is critical; even 1⁄16″ error accumulates. |
| Bags & home dec | ½″–1″ | Heavier fabrics and hardware require wider clearance. |
| Baby & children | ⅜″–½″ | Slightly narrower for small, fiddly pieces. |
Practical Tips
- Use the seam guide on your machine's needle plate or attach a magnetic seam guide for consistent stitching distance.
- When adding seam allowances to Burda patterns, trace the stitching lines and add ⅝″ with a ruler or a seam allowance tool.
- Press seams after stitching—pressed seams sit flatter, making subsequent seams more accurate.
- Clip curved seam allowances (concave curves) or notch them (convex curves) so the seam lies flat without pulling.
Calculate Seam Allowance Adjustments
Need to convert between seam allowance widths or calculate total fabric adjustments? Use our seam allowance calculator.
Seam Allowance Calculator →Pattern Size Charts
Find body measurements for each pattern brand: