Ask away! I find that most big-name patterns have awful instructions.

What we're trying to figure out is if 4 inches of unstreched knit will stretch to whatever length is marked on your pattern envelope (the "from here to here" arrows). Simplicity has you use the gauge on the envelope rather than telling you "you need a knit with 50% stretch". For example, for a 50% stretch, the pick-a-knit rule would be that 4 inches on the cross grain stretches to at least 6 inches.

It's the cross grain of the knit, the stretchiest directon, that you want to test. This is the grain line that will be going over and across your bust line (and other curvy parts).

Here's how you figure out the "pick a knit" rule:

1. Take your knit fabric and find the cross grain, from selvege to selvedge. If you have tube knit yardage, the cross grain is across the width of the tube.

2. With the fabric relaxed and unstretched, measure a 4-inch section/line across the cross grain. For convenience, put in a pin, then measure 4 inches from that pin and put in another pin.

3. Take your measured section/line and lay it over the pattern envelope where your "pick-a-knit" gauge is. You want one pin point on top of the "from here" arrow, and you're going to hold the other pin point in place (unmoving) while you pull the measured section of knit to see how far it stretches.

4. Pull the "from here" pin point towards the "to here" arrow. Does that 4-inches of measured cross-grain stretch out to the "to here" arrow?

If the 4-inch section of knit stretches at least that far, then your knit is stretchy enough to use for that pattern.

Using a knit that stretches more than that probably won't cause you any problems, but if the knit you have doesn't stretch at least that far, it won't have enough "give" to fit over your bust and curves properly.

Some knits have good stretch in both directions, and others have good stretch only on the cross grain. You want to measure the stretchiness on the grain line that will be going across your bust and around your body.

CMC
Probably more detailed than it needed to be.

oh thank you that's perfect!