Picking the right budget for your campaign is critical to success. The first step of the “Budget & Schedule” setup is to assign a budget for your campaign. Facebook gives you two budgeting options:
1. Daily budget:
Facebook will spend this sum on delivering your ads every day during your campaign. When you set your daily budget, you’re telling Facebook to get you roughly your daily budget’s worth of the results every day.
Some days, when Facebook spots high-potential opportunities, it may spend up to 25% more than your daily budget (and then lower the spend on the low-potential days). As you select the daily budget, your daily ad spend could look like a set of curves.
Don’t worry, that’s completely normal and means that Facebook’s auto-optimizing your ad delivery (which is a good thing).
2. Lifetime budget:
Facebook will divide the total campaign budget more or less evenly across the campaign dates. If you set a lifetime budget, Facebook will ask you for the campaign dates, so that it can calculate the average spend for each day.
We recommend that you set a daily budget and an unlimited campaign duration so that you can later edit the size of your daily budgets and pause the campaign whenever you see fit.
Important! You can’t change an ad set’s budget type after the ad set has been created. Make sure you make the right selection during the campaign setup.