Rates will vary depending on the type of work you require (copy-editing, development editing, proofreading, rewriting, research, etc.), but also on the length of the text, on the number of additional elements involved (number of images and tables to be reviewed, for example), on the level of difficulty (is it heavily technical, for example, or has it been written by a non-native English speaker?), and also on the turnaround time required.
Moreover, there are different levels of copy-editing: you might require a basic SPAG (spelling, punctuation and grammar) copy-edit or you might require a far more substantive edit. Within proofreading, too, there is often scope for this to turn into ‘proof-editing’, meaning a more invasive check that verges on copy-editing. Needless to say, all of these various tasks will require different levels of specialist knowledge and expertise.
I will normally base my rates on the recommendations of the Society for Editors and Proofreaders (see here); however, as I have discussed above, rates will depend on the level of skill and expertise required for the job and, ultimately, on the time required to do the work. Therefore, determining a rate for your job will inevitably involve some initial discussion, and probably also an assessment of a sample of the text, in order to determine exactly what it is that you are looking for.
I will always try to offer you as fair a rate as possible, while not compromising the integrity of the expertise that I am offering.
I am always happy to negotiate. Drop me a line.