Sometimes you know exactly what you want to spend on pay per click advertising and all your other marketing channels. Other times, you may feel a little lost, whether you have or have not run PPC campaigns previously.
If you have run Google Ads or other PPC campaigns in the past and have good data, determine the number of leads and / or sales you want and back out the math based on prior cost-per-conversion and other key metrics.
If you haven’t run a campaign before or don’t have data you believe in, you can still use a similar process. Create low, high, and middle ranges for key metrics like cost-per-click, conversion rate, and (if doing lead campaigns) offline sales conversion rate. Employ some rough math to create several ranges for cost-per-sale, put in the number of sales desired, and factor in your risk tolerance and profit margin. If you haven’t worked through this process before, working with a PPC agency is your best bet to help you develop your forecasts.