Start with an oversized T shirt and lay it out on a flat surface.

From the bottom hem measure the desire shortest length of your skirt. I went 12 inches from the bottom. Mark with chalk.

At this point you can simply cut across and make the skirt one-length. I chose to cut on a bias. For this, mark just below the armpit of the opposite sleeve and cut diagonally.

Finally, make a little snip in the hem and thread either a string or a pretty ribbon to make a drawstring.

That's it! Easy Peasy!