How much should I charge?

[haveigotnewsforyou]

Hi All

I'm currently temping and planning to go self employed as I want to work more hours for several companies.

I'm currently earning £15 per hour through an agency and have been told I should charge more to cover my tax/National Insurance/holidays/sickness.

Does anyone have any idea how I should calculate this? I don't want to overcharge but equally don't want to lose out.

Thanks a lot

[Grevling]

I always add 25% to cover "employee overheads". This is Employer NI, Holidays etc. So £18.75 per hour.

Roughly 10% will cover holidays and another 10% for Employer NI. 5% misc.