The stretch factor is measured on DOGS and grain-line. Read about DOGS and grain-line on this page. When the fabric stretches only on DOGS, we say the fabric is stretchy only in one direction. When the fabric stretches on DOGS and grain-line, we say that fabric stretches in both directions.
Stretch factor for fabric means how much the fabric stretches.
Sewing patterns for elastic fabrics must specify for what type of fabric they were designed: fabric that is elastic in one direction, or on both directions. Also, for every stretch direction, the pattern must include the stretch factor or stretch percentage.
How to determine the stretch factor for our fabric?
The percentage
- Identify the directions we want to measure the stretch factor on our fabric: DOGS or grain-line
- Take a segment of 20 cm long in the chosen direction. The end of the segment is marked by our thumbs. When the fabric has some kind of border, avoid taking it in our segment.
- The hand with the thumb pointing at 0 (zero) will remain still
- Stretch the fabric pulling only the right hand
- Stretch easily, do not pull to rip the fabric!
- Note the value where our right thumb is pointing
- Look for your value in the table below and see what your fabric stretch factor is.
HOW MUCH YOUR FABRIC HAS STRETCHED: | THE FABRIC STRETCH FACTOR IS: |
21 cm | 5% |
22 cm | 10% |
23 cm | 15% |
24 cm | 20% |
25 cm | 25% |
26 cm | 30% |
28 cm | 40% |
30 cm | 50% |
Examples
Below are 3 examples of different fabrics. I want to determine the stretch factor on DOGS for all 3 fabrics. Click on pictures to enlarge.
Cotton jersey
The blue line shows where 20 cm is. But the right red arrow shows that the fabric stretch to 25 cm. From the table above we see that this fabric has a 25% stretch factor.
Synthetic jersey
On the synthetic jersey, the blue line shows where 20 cm is. The right red arrow shows that the fabric stretch to 27 cm. From the table above we see that this fabric has a 35% stretch factor.
Lycra
On the Lycra fabric, the right red arrow shows that the fabric stretch to 27.5-28 cm. From the table above we see that this fabric has a 35-40% stretch factor.