How much should I charge for custom tailoring?
A general rule of thumb for handcrafts is to charge three times the cost of your supplies. This covers your time and creativity. I don’t know if that’s practical for sewing. Do the math and see what you think. If this lady often has dresses made, ask her what she usually pays. Then, give a bit of a discount. Or, check your local phonebook and see if there are any seamstresses in your area. If not, dry cleaning shops usually have a tailor on call. Ask them how much that tailor or seamstress would charge for a dress. Get all the info you can, and then make a decision. It would probably be best to charge per project rather than per hour, I’d say.
I’d charge between $15 and $20 per hour, plus the cost of all fabric and notions. I imagine that your geographic location would make a difference in an hourly rate. I n this area a seamstress will get about $10 for shortening pants, or taking in/letting out a waist, and a skirt hem would run from $12.50 to $25, depending on the width, kick pleats, etc. This is a professional service. If you are good at what you do, you should be compensated accordingly.