Count can be used to return the count of items or elements in a target. In this example, count will return 4.

$items = @("apple", "banana", "orange", "grapes")

$items.count

The Get-ChildItem cmdlet with the Count option can be used to count the number of files and folders in a directory. For example, to count the number of files and folders at C:\Example Directory:

(Get-ChildItem "C:\Example Directory").Count
15

Recurse

This will not count files and folders below C:\Example Directory. The -Recurse option can be used to count objects below C:\Example Directory.

(Get-ChildItem "C:\Example Directory" -Recurse).Count
72

Where clause

Let's say we want to count all of the files that have not been modified in the last 365 days. 

$One_year_ago = (Get-Date).AddDays(-365).ToString("yyyy-MM-dd")
$source = "C:\Example Directory"
$File_to_check = (Get-Item -Path $source).LastWriteTime.ToString("yyyy-MM-dd")

if (($File_to_check) -lt ($One_year_ago)) {"File to check less than One year ago"}

Measure Object

If you want to also determine the size of the directory, in bytes, KB, MB, GB, or TB, the Measure-Object option can be used. In this example, there are 72 files at and below C:\Example Directory, and the size of the directory is 27,136 bytes.

Get-ChildItem "C:\Example Directory" -Recurse | Measure-Object -property length -sum

Count    : 72
Average  : 
Sum      : 67181464
Maximum  : 
Minimum  :
Property : Length 

We can adjust the output to only show count and bytes.

$y = (Get-ChildItem "C:\Example Directory" -Recurse | Measure-Object -property length -sum)
echo $y.count
echo $y.sum

72
67181464

Instead of displaying 67181464 bytes, we can display the size of the files in the directory in KB (or MB, GB, TB).

$y = (Get-ChildItem "C:\Example Directory" -Recurse | Measure-Object -property length -sum)
echo $y.count
echo "{0:N0}" -f ($y.sum / 1KB) + " KB"

72
65,606 KB

There may be a scenario where the comma in the output is problematic. Let's drop the comma.

$y = (Get-ChildItem "C:\Example Directory" -Recurse | Measure-Object -property length -sum)
echo $y.count
$x = [math]::Round($y.sum) / 1024
[int]$x

72
65606