It’s pretty simple to estimate your reach with Facebook ads. Facebook provides a tool that shows you an approximate reach number.
Here are two screenshots of the adset level with the reach estimate highlighted
In the first image you see the targeting is USA , Men and Women and ages 18–65+. The daily reach for this $20/per day budget is between 7,300 and 34,000. This is a wide range but allows for comparison. (see the second image)
In the second image, the targeting is again $20/day and USA but this time only targeting people from 30 to 50 years old. You can see that the reach estimate has changed drastically. It’s now 5,600 to 20,000, which is a lot smaller than the previous adset.
When I run ads for clients at the Exfil Project I will sometimes take advantage of these differences if there is flexibility in the ad age ranges.
For instance, sometimes by adjusting the age range by a year or two on either end you can get a higher reach estimate. It’s definitely something to look at, but if you have a specific range, there may not be much you can do about it.