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Rounded Rectangle Stitch Line Length

Enter the width, the height and the corner radius of the stitch line. The page gives the exact perimeter with its straight sides and quarter circles, and draws it, ready to feed the thread and holes calculators.

Stitch line length (mm)

302.831853

0.302832 m · 2 × (100 + 60) − 8 × 10 + 2π × 10

Enter the size of the stitch line itself, not of the cut outline. The geometry is exact; cutting and stitching are not.

How it works

  1. Enter the width and the height of the line you will stitch, in millimetres.
  2. Enter the corner radius, 0 for square corners.
  3. Read the perimeter and check the drawing.
  4. Copy the figure or use it in the thread length estimator.

What people use it for

  • A card holder or a case

    Know the length of the stitch line around the rounded outline before you mark it.

  • Different corner radii

    Compare 5 mm and 10 mm corners on the same panel.

  • Feeding the thread estimate

    Use the perimeter as the seam length of the thread length estimator.

Questions

What is the formula?
Perimeter = 2 × (W + H) − 8 × r + 2 × π × r. The four straight sides lose 2 × r at each corner and the four quarter circles add up to one full circle of radius r.
What radius is allowed?
From 0 up to half of the smaller side. At exactly half the short side, two corners meet and the shape has no straight part along that side.
Is it the length of the cut or of the stitching?
It is the length of the line you describe. If you stitch inside the cut edge, enter the width, height and radius of the stitch line itself, not of the cut outline.
How accurate is it?
The geometry is exact. Cutting, marking and stitching are not, and the page does not claim a precision for them.