We recently created a Free Facebook Ad Calculator.
Start by entering your revenue goal and price of service or product. The Facebook Ad Calculator will then calculate the number of customers (unit sales) you’ll need to get.
In the funnel conversion rate section, enter your landing page conversion rate and Facebook ad CTR (click-through-rate). If you don’t know these figures yet you can estimate 24% landing page conversion rate (24% of FB visits opt-in with email on your landing page for example) and 2% CTR (2% of People on FB who see your ad, click on it) but change to your actual numbers as soon as you have good data. The Facebook Ad Calculator will then determine the required ad impressions (times people see your ad) and leads (people who visit your landing page from Facebook Ad).
In the last section, enter your CPC (cost-per-click). The Facebook Ad Calculator will then calculate your required Facebook Ad spend and if the campaign is profitable or leading to a loss.
Link to Google Sheet here: Facebook Ad Calculator. To edit, make a copy and save to your Google Drive.