The formula
Results = budget ÷ cost per result
Sales = results × conversion rate
Cost per sale = budget ÷ sales
Example: a 5,000 budget, 15 per message, and a 10% message-to-sale rate. Result: about 333 messages, 33 sales, and a cost per sale of about 150.
Why conversion rate matters more than cost per result
A message at 10 with a 5% conversion rate means a sale costs 200. A message at 20 with a 15% rate means a sale costs 133. The "more expensive" campaign is the more profitable one. Always measure cost per sale, not cost per message; WhatsApp Message Campaigns on Facebook: Measure Cost per Order, Not per Conversation shows how to track it.
How to find your conversion rate
- Count conversations or leads for a week, and how many actually bought.
- Separate sources: message ads convert differently from lead forms.
- Review it monthly; response speed and sales team quality affect it as much as the ad does.
If the resulting cost per sale is above your product's max CPA, raising the budget only grows the loss. Improve conversion rate or lead quality first.
FAQ
What is a normal message-to-sale conversion rate?
It varies widely with product and response speed, usually between 5% and 20%. What matters is measuring it for your own business.
Does the calculator work for ecommerce campaigns?
Yes: use cost per click as cost per result and your site conversion rate as the rate to estimate sales from your budget.
Why do actual results differ from the estimate?
Cost per result changes with competition, seasons and ad fatigue. Use the calculator to plan, then watch real numbers daily.