Unfortunately, there’s no clear answer to this question, because it entirely depends on your industry, your goals, and, most importantly, your budget.
If you knew you could, at the very least, double the money you spend on your ads, your budget would probably be whatever you could afford.
So how do you decide your initial budget?
The good news is that there is always a minimum amount that needs to be spent to acquire a conversion. If you know the fewest number of conversions you need in a given month to stay profitable, then you can use these two numbers to determine your budget.
This minimum amount is different for every business, and can only be accurately determined via either a Google Ads account audit, creating an account and monitoring the results for an ‘adjustment period’ of one month, or from your own knowledge of your business.
If you’ve never run Google Ads before, it’s impossible to know how well all of the factors that go into their creation will work.
Once your ads have been fine-tuned to your business & your goals, then your optimum budget will, in effect, reveal itself.
Like a genie.