Online RulerMark a Small Seam Allowance
Measure the allowance inward from the cut edge and mark the stitching line. If your pattern already shows the stitching line and you are adding an allowance before cutting, measure outward to mark the cut line. Use the amount and unit given by the pattern.
- The seam allowance is the distance between the cut edge and the stitching line.
- Measure across the gap at a right angle to the edge at each mark. On a curve, the ruler changes direction as you move along the edge.
- A verified paper ruler lets you mark fabric flat on the work surface. Pick a scale with clear ticks for the amount you need.
- Find the seam allowance in the pattern directions. Check whether the printed outline already includes it. Identify the line or edge you will use as your starting point before you mark the fabric.
- Print the AR Ruler scale at actual size and check its 10 cm test line with a physical ruler. Choose the metric or inch scale to match the pattern. Keep the fabric flat and relaxed while you work.
- Place zero at the cut edge or at the marked stitching line. Set the scale across that line at a right angle and make a small mark at the specified distance. Repeat along the edge, placing marks closer together where the curve turns more sharply.
- Join the marks with a light line. Use a straightedge on straight spans and follow the dots on curves. Check the gap again at a few points, especially near corners and where the curve changes direction.
Use the right starting line
On fabric that has been cut with the allowance included, start at the cut edge and mark inward if you need a stitching guide. When the pattern gives only a stitching outline, start on that outline and mark outward before cutting. Follow any separate directions for hems or other edges with their own allowance.
Follow curves and corners
On a curve, turn the ruler at each mark so it crosses the edge squarely at that spot. Keep the fabric still as you turn the ruler. At a square corner, extend the marks from each straight side until the lines meet. Mark that intersection so you can see where the direction changes.
Keep marks fine
Try your fabric marking tool on a scrap first. Use small dots or fine strokes so the line has a clear center to follow. If the fabric shifts as you draw, hold it lightly near the mark and release it before taking the next reading. Let the fabric lie in its natural shape.
Can I use the screen ruler?
Yes. Verify the calibration and use the screen to check the distance. A paper scale is easier to move along fabric as you mark.
What if the cut edge is frayed?
Use the edge of the woven fabric as your starting line. Leave loose threads outside the measured span.
What if my allowance falls between ticks?
Use a sewing gauge or a ruler with a tick for that amount. That gives each mark the same reference.