Freelance graphic design for agency - how much to charge?

[MitchT]

Looking on the website of a good local design/brand agency with global offices, it says the following ...

We’ve a good bank of talented freelancers who we use on a regular basis, but we’re always looking for more. So if you’re a designer, writer, artworker or all-round creative genius then please get in touch via the relevant email address below. You’ll need to send us a covering letter, a CV and some examples of your best work, and please put your area of expertise, the studio you’d like to work in and your day rate in the subject line. Eg: ‘Freelance Senior Designer, Leeds, £xxx’.

I'm currently a 'PAYE pleb' but I'm considering other options, however, I wouldn't have a clue how much to put for the day rate! What do freelancers sat within the offices of design agencies charge?

[anonymous-user]

I used to pay anything between £150 and £250 per day for a freelance GD depending on portfolio, now I have outsourced all my digital projects.

[anonymous-user]

A sensible starting point would be to take the typical gross salary of a full time employee doing a similar job, work it down as a day rate, then add 50%.