Choose a Pattern Size and Blend Between Sizes

A pattern size is a reference to that maker's measurement chart. Your bust, waist and hip measurements may fall in different columns. With a multi-size paper pattern, you can sometimes connect those size lines to make a more useful starting point. Work on a tracing so the original remains available for another attempt.

Jump to: Read both charts · Choose a starting size · Draw the blend · Check seams · Checklist

1. Separate body size from garment size

Compare current body measurements with the pattern's body-measurement chart. Then read the finished-garment chart and the description of the intended fit. These answer different questions: which body measurements informed the size, and how large the sewn garment will be.

The difference helps describe ease. Positive ease gives additional room; some stretch garments use negative ease and depend on suitable fabric. There is no single allowance that works for every garment. Check the maker's guidance, fabric requirements and the activities you expect to do.

Illustrative example using fictional figures: a 100 cm body hip and a 108 cm finished hip leave 8 cm of difference. That arithmetic describes this comparison only. It does not establish that 8 cm is necessary or sufficient, or explain where that room sits around the body.

2. Choose the relevant starting size and range

Follow the pattern's selection instructions. A fitted bodice may require high-bust and full-bust measurements or a specific cup option; a skirt may emphasize waist and hip. Ready-to-wear labels and a size used successfully in another brand are poor substitutes for this check.

If the maker offers separate size ranges, check which range suits the project before tracing. Overlapping numbers do not necessarily mean identical shapes. Do not join lines from separately drafted ranges unless the maker provides a method.

Consider whether a blend is needed at all. A loose area may already accommodate your measurements, although using that spare room can change the intended silhouette. Check both comfort and appearance in a test garment.

3. Connect sizes at the correct body levels

Identify the size-line styles and mark the pattern's waist, hip and other relevant levels on your tracing. Check required length changes first so the widest part will not end up above or below the place you need it.

For a simple skirt, mark the chosen waist-size line at the waist and the chosen hip-size line at hip level. Draw a gradual connection that follows the character of the side seam, without a sharp corner. Apply the corresponding blend to the front and back. Keep center lines and grainlines as intended by the pattern.

Use the maker's specific tutorial for darts, princess panels or unusual seams. A dart crossing an altered edge must still fold into a coherent seam. Changing just the visible outer edge without considering the dart can leave a mismatch when sewn.

4. Check every affected joining piece

Lay adjoining paper pieces together along their stitching lines, working from notch to notch. Check that lengths and marks still correspond, allowing for any intentional easing specified by the instructions. Comparing cut edges alone can mislead you on curves.

Update the associated waistband, facing, lining or adjoining skirt section. Keep a written list of affected pieces and tick each off. Do not automatically substitute a different sleeve size: the sleeve and armhole must remain compatible.

Blending changes selected dimensions within the pattern's existing design. It does not automatically correct shoulder slope, bust projection, posture, seat shape or torso length. Those may need a targeted adjustment. If your measurements fall outside the printed range, seek a supported grading method or a different starting pattern rather than extending lines by guesswork.

Before cutting your main fabric

• Body and finished measurements have both been checked.
• The selected lines belong to a compatible size range.
• Blends reach the right level without abrupt corners.
• All affected pieces and joining seams have been checked.
• A toile has tested the blend, movement and remaining shape questions.

For a short reference while you work, see the Measuring Guide.

Further reading: Seamwork's sizing guidance; Cashmerette on blending and its limits; Cashmerette on separately drafted ranges; Tilly and the Buttons' illustrated blending tutorial.