How to Get File Size in PowerShell (5 Methods)
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How to Get File Size in PowerShell (5 Methods)

PowerShell Tips Editor 4 min read
How to Get File Size in PowerShell (5 Methods)

Disk space alerts fire at 3 AM. A folder that should hold weekly logs is somehow 50GB. A single file is blocking a backup job. These are the moments when you need to quickly measure file sizes with PowerShell — and the tool handles it in seconds without opening File Explorer. This guide shows 5 reliable methods to get file size in PowerShell, from single file lookups to recursive folder size reports formatted in KB, MB, and GB.

Method 1: Length Property

Every file returned by Get-ChildItem or Get-Item has a Length property containing the file size in bytes:

# Get size of a single file in bytes
$file = Get-Item 'C:\Logs\app.log'
$file.Length

# Size of a specific file directly
(Get-Item 'C:\Logs\app.log').Length
10485760

The Length property is always in bytes. Directories do not have a Length property — it will be $null for folders. Use Get-Item -Path path -File or check PSIsContainer if you’re unsure whether a path is a file or directory.

Method 2: Get-ChildItem with Select-Object

Combine Get-ChildItem with Select-Object to get file sizes alongside names in one clean output:

# List all files with sizes
Get-ChildItem 'C:\Logs' -File |
    Select-Object Name, Length |
    Sort-Object Length -Descending

# Filter to specific extension
Get-ChildItem 'C:\Users\Public\Documents' -Recurse -File -Filter '*.pdf' |
    Select-Object Name, Length |
    Sort-Object Length -Descending
Name              Length
----              ------
system.log      16777216
app.log         10485760
error.log        4194304
debug.log         131072

Method 3: Convert Bytes to KB, MB, GB

PowerShell understands KB, MB, and GB multipliers in expressions. Use them with calculated properties for human-readable output:

Get-ChildItem 'C:\Logs' -File |
    Select-Object Name,
        @{ Name='SizeKB'; Expression={ [math]::Round($_.Length / 1KB, 1) } },
        @{ Name='SizeMB'; Expression={ [math]::Round($_.Length / 1MB, 2) } } |
    Sort-Object { $_.SizeKB } -Descending |
    Format-Table -AutoSize

# Single file with formatted size
$file = Get-Item 'C:\Logs\system.log'
'Size: {0:N2} MB' -f ($file.Length / 1MB)
Name         SizeKB  SizeMB
----         ------  ------
system.log  16384.0   16.00
app.log     10240.0   10.00
error.log    4096.0    4.00
debug.log     128.0    0.13

Size: 16.00 MB

PowerShell’s built-in multipliers: 1KB = 1024, 1MB = 1048576, 1GB = 1073741824, 1TB = 1099511627776. Use these in conditions too: Where-Object { $_.Length -gt 10MB }.

Method 4: Get Total Folder Size

Combine Get-ChildItem -Recurse with Measure-Object to sum all file sizes in a folder:

# Total size of C:\Logs and all subfolders
$total = Get-ChildItem 'C:\Logs' -Recurse -File -ErrorAction SilentlyContinue |
    Measure-Object -Property Length -Sum

'Total size: {0:N2} MB' -f ($total.Sum / 1MB)
'File count: {0}' -f $total.Count

# Size of multiple specific folders
'C:\Logs', 'C:\Backup', 'C:\Scripts' | ForEach-Object {
    $size = (Get-ChildItem $_ -Recurse -File -ErrorAction SilentlyContinue |
             Measure-Object -Property Length -Sum).Sum
    [PSCustomObject]@{
        Folder  = $_
        SizeGB  = [math]::Round($size / 1GB, 3)
    }
}
Total size: 30.13 MB
File count: 12

Folder     SizeGB
------     ------
C:\Logs     0.030
C:\Backup   2.147
C:\Scripts  0.001

Method 5: One-Line Recursive Size Report

The most useful pattern for disk space investigation — find the largest subdirectories:

# Top 10 largest immediate subdirectories of C:\
Get-ChildItem 'C:\' -Directory | ForEach-Object {
    $size = (Get-ChildItem $_.FullName -Recurse -File -ErrorAction SilentlyContinue |
             Measure-Object -Property Length -Sum).Sum
    [PSCustomObject]@{
        Folder = $_.Name
        SizeGB = [math]::Round($size / 1GB, 2)
    }
} | Sort-Object SizeGB -Descending | Select-Object -First 10 | Format-Table -AutoSize
Folder      SizeGB
------      ------
Windows     23.47
Users       18.92
Program Files 12.34
ProgramData  5.81
Logs         0.03

Common Errors and Fixes

  • Length is null on directories — use Get-ChildItem -File: Accessing .Length on a directory object returns $null. Always add -File to Get-ChildItem when you only want file sizes, or check $_.PSIsContainer -eq $false before accessing Length.
  • Permission denied on system folders: Measure-Object stops summing if it hits a folder where access is denied. Add -ErrorAction SilentlyContinue to Get-ChildItem to skip inaccessible folders and continue summing the rest. The total will be a lower bound rather than the true size.

Related Cmdlets / See Also

Wrapping Up

Getting file sizes in PowerShell is simple: use the Length property for individual files, Measure-Object -Sum for folder totals, and calculated properties with / 1MB or / 1GB for human-readable output. Add -ErrorAction SilentlyContinue when recursing to handle permission errors gracefully. Your next step: run the top-10 largest subdirectories report on your system’s largest drive.

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