The formula
Total budget = results × expected cost per result
Daily budget = total budget ÷ days
Example: you want 300 messages in a month at an expected 15 per message. Budget = 4,500, or 150 per day, and 5,400 with the safety margin.
Where does "expected cost per result" come from?
- Your own account: the last 30-day average for the same objective and country is the most accurate source.
- A test campaign: with no data, run a small 5 to 7 day test.
- Profitability: never exceed the max CPA your margin allows.
Why add a 20% margin?
The first days of any campaign are usually more expensive because of the learning phase, prices rise during seasons and at month end, and you'll need to test more than one ad. The margin keeps the budget from running out before you reach the goal.
Budget allocation tips
- The daily budget should allow about 50 results per week per ad set to exit learning, or get as close as you can.
- Don't split a small budget across many ad sets; two strong ones beat five weak ones.
- During peak seasons, raise budgets gradually a few days before the peak, and watch balance in hours because spend accelerates.
FAQ
What is the minimum budget for Facebook ads?
Meta allows very small daily budgets, but a practical budget is one that allows several results a day so the system can learn. Multiply your cost per result by 5 to 10.
Is a daily or lifetime budget better?
Daily budgets are easier to control and monitor for most campaigns; lifetime budgets suit promotions with fixed start and end dates.
How do I estimate cost per result for a new account?
Run a small test for a week, or start from averages for similar campaigns in the same country and industry, then adjust.