Adjusting Facebook Ad Budgets towards a target ROAS Goal

Here is a simple formula to adjusting your daily Facebook Ad budget towards a target ROAS based on past performance.

NumberOfDays	The time period for which you want to base performance.
AmountSpent	How much did you spend during the time period.
ActualROAS	The ROAS performance of your ads during the time period.
TargetROAS	The ROAS target you are trying to achieve.

How I use this

1. I maintain an evergreen campaign structure so that I can easily measure past performance.
2. My performance target is generally an ROAS of 4.5
3. My lookback time period is generally 7 days

Once a week (or sometimes daily if we are in a period of high activity or if we have launched a new promotion), first thing in the morning, I look at the past 7 days and run the above formula for each of my campaigns.

• If my target ROAS is very close to my actual ROAS, then I don’t bother with the calculation, nor with adjusting budgets.
• If the results call for a decrease, then I decrease the budgets.
• If the results call for an increase, then I increase budgets, but usually by no more than 10%.