Type of work – Some alterations is much easier to accomplish than others.  For example, shortening a dress is much easier than lengthening it and letting it out is also a lot harder than taking a dress in if it is too big.  The type of work you request may have a significant impact on the price.

A number of changes – Tailors cannot charge the same fee for a simple project as they would for doing numerous changes.  The more changes you need to do to the dress will affect the cost.

Fabric type – Delicate fabrics such as lace and silk are a lot harder to work with than other types.  Extreme caution is required in order to keep the fabric in great condition when the fabric is delicate of nature and might result in extra costs.

Materials used – Do you need to add some more detail to the dress?  Beading, tulle fabrics, overlays, embroidery, and other decorative elements will all cost a bit extra to accomplish the finished effect you’re looking for.

Type of dress – Some types of dresses are a lot easier to modify than other types.  A wedding dress or corset, for example, is a lot more complex than a simple A-line dress.  The type of formal dress you have could affect the price.

Labour intensity – Some dressmaking tasks take a lot longer than others.  Beading, for example, takes hours because each bead has to be hand sewn to the dress.  Therefore, the time it takes to do the modifications will also affect the alteration fee.

The condition of the dress – Is the dress still relatively new?  Or is it extremely old?  Old, worn out dresses usually require more repairs, and matching fabrics for modifications are often hard to find.