If it’s awkward for you to measure yourself, ask a friend to help you. If you are measuring yourself, it is best to do in front of a full-length mirror. To measure your bust properly, wear a supportive bra but not a push-up or heavily padded bra, because this may not be what you will wear with the dress. If you don’t need to take in a loose-fitting bust, you can just measure the hips and waist.
If the dress is flat on a work surface, pull the measuring tape across the waistline and double that amount to get your measurement. Repeat this for the hipline.
Always label your measurements so you don’t accidentally switch the hip and waist measurements.
If you’d like to make a floor-length dress into an everyday dress, for instance, you might want it to cut around 20 inches (51 cm) from the bottom so the dress falls around your knees.
If you’re adjusting the hemline, you’ll need to fold at least 1⁄2 inch (1. 3 cm) of the bottom fabric over and pin it. Then, you can straight stitch the bottom hemline leaving a 1⁄4 inch (0. 64 cm) seam allowance. For example, if you’re taking in the waist by 4 inches (10 cm), make a mark that’s 1 inch (2. 5 cm) from the original seam. Remember to do it on both sides of the waist. [4] X Research source
If you want to take in more of the dress for a more snug fit, you could extend your new seam line up to the armpit of the dress. To make the skirt of the dress more form-fitting, you could also extend your new seam line down both sides of the skirt.
Use a thread that matches the color of the existing thread so your new seam doesn’t stand out.
You may want to iron the dress so the excess fabric lies flat. You might not notice it as much if it’s completely smooth.
If you have a serger, you could serge the seams instead.
