Hey there,
There's a game design job I'm applying for (I have 4 years experience) and it'll be transitioning from a salaried job to freelance / hourly. In the first stage call with HR I was asked what my hourly rate would be. On the application, I put £18 which was £35,000 salaried but on the call I found out it would be freelance and so I'd need to charge more as it would need to cover pension, holiday and sick days and everything that doesn't come with a salaried role.
I asked what their budget was and ofc they didn't say but they said "I could add a little more" to what I'd given but not a lot more. Online is generally saying for a mid, I could ask for £30-60 and with them saying I could "add a bit more" onto £18, I'm not surely sure if I could push for £30 or if that's a totally valid and sensible request (with it being the lowest end of that scale).
Any insight would be amazing

Replies
We have some estimates here on our wiki, with links to more info
http://wiki.polycount.com/wiki/Freelance#Freelance_Rates
Personally, I would highly recommend this book. You can usually find an older version for free in a library too.
Graphic Artists Guild Handbook: Pricing & Ethical Guidelines
It has so much info it's amazing, and it's kept up to date. Literally a gold mine for commercial artists.
double your expected full time salary and let them haggle you down a bit if you really want the job. The extra money is because you can be let go basically immediately and it doesn't bother the employer because it's still cheaper in the long run than a full time hire.
pay an accountant for an hour an have them explain why it's an awful idea to use an umbrella company/agency to manage your pay (saved me 300quid a month when i did it) - its been 10 years since i went back to full time so tax laws have changed but self assessment is not difficult or much work at all so don't be afraid of it.