i'm just looking for the accurate number by which to multiply an hourly rate to get a salary.

i'll show my workings and would appreciate if anyone could make my number more accurate:

365.25 days a year
average of nearly 261 week days a year
minus 20 days holiday (is this too little?)
241 days
how many public holidays are there a year? bank holidays and stuff? about 10?
231 days
and do most companies let people take free holidays from christmas to new years? so thats another couple of days off?
228 days.
then 9-5 with one hour lunch break is 7 hour day

7x228=1596 hours of work a year

so minimum wage (£5.35) as a salary is £8,540
and a £20k job as an hourly is £12.53

but i guess some hourly waged jobs let people have paid holiday too? what sort of thing? are there minimum holidays?

i doubt anyone knows full answers to these things, but if people could let me know how the jobs that they've had relate to the speculations i've made above, that'd be really useful. not just for me, but it'd be great for this magical formula to exist so that people could weigh up different job options.