I can't help you with industry norms but I can tell you how an employer thinks. We are told by our accountants to remember that staff earn paid holiday at a rate of 12.07% of their employed hours - so an invisible 12.07% extra pay if that makes sense. Then there are employer national insurance contributions that we pay that mean you get benefits if you're out of work - hardly anything but still a lot better than the diddly swat that you get as self employed. Finally your employer has to contribute into your pension pot. This might only be a tiny amount but it's still something that is extra on top of your take home pay. All of this means that employers don't get to keep all the difference between what you earn and the value of treatments that you do.
Your employer will be encouraged to pay you a maximum of 35% of the services that you earn. It may be that this isn't very much, in which case you and your employer need to think about how to increase your revenue.
So what I suggest is that you discretely calculate how much revenue you generate in a month, separated out as product sales and services. It helps to drill down into the numbers - are you mostly looking after simple walk-in enquiries, trims, kiddy cuts, blowdry's? Or do you have a returning client base who ask for you? Do you do more technically demanding work or do you pass that over to other stylists? Are you upgrading clients from the basic services to add on services - can you track a client's history over 5 services to show how they spend more on repeat visits. Do you sell a product to one client in 5? This information is all the stuff that helps you negotiate and then it doesn't matter about what is "fair" or what others earn, it becomes a conversation about you and your value - which is more powerful.
if your employer really values you they'll pay you a good rate because they won't want to lose you. I've got a good team and I check market rates several times a year to make sure I'm paying enough to make my staff feel valued and appreciated.
