This guide is for Web developers or API users who may have a printing background but are new to embroidery. One of the most common questions we get is:

'Why does the stitch count increase when an image is scaled up?'

Design size vs stitch count

For example, the letter 'B' at 10mm has 251 stitches, while at 50mm it has 2,670 stitches.

Stitch view	TrueView

Why?

1. At small sizes, stitches fit neatly.
2. At larger sizes, columns become too wide for a single stitch, leading to:
3. Gaps and shading.
4. Misaligned curves.
5. Extra needle penetrations (to avoid fabric tearing).

Result: Scaling from 10mm to 50mm increased size by 5× but stitches by more than 10×.

Conclusion: Embroidery designs are not infinitely scalable. Beyond a certain size, the design won’t stitch well.

Scaling artwork with auto-digitizing

Using Smart Design in EmbroideryStudio (same as api/bitmapArtDesign):

Bitmap artwork	Auto-digitized embroidery

Note:

1. A small bitmap generated 5,212 stitches.
   
2. A version scaled 3× larger generated 24,825 stitches.
3. Stitch count increased 4.5×, not just 3×.

Reason: The stitch type chosen by Smart Design greatly affects stitch count.

Stitch count & stitch types

There are two main stitch categories that behave differently when scaled:

Satin stitch

Crosses a column with a single stitch.

Example:

1. 20mm × 3mm object → 155 stitches.
2. Scaled to 40mm × 6mm → 375 stitches (~2.4× more).
3. Extra stitches come from density adjustment – software reduces stitch spacing at larger sizes for quality.

Tatami stitch

Fills wide areas with multiple rows.

Example:

1. 10mm × 10mm square → 262 stitches.
2. Scaled to 20mm × 20mm → 771 stitches (~2.9× more).
3. Not perfectly quadratic – it should be 4× – due to how short boundary stitches are handled.

Key points

1. Stitch count increases faster than size when scaling embroidery designs.
2. Satin stitches behave more linearly – Tatami stitches behave more quadratically.
3. Over-scaling leads to poor embroidery quality – gaps, excessive penetrations, or weak fabric.
4. Developers should not assume proportional scaling like in graphics.