Run this PowerShell script to list all folders over a specified size. The default script uses 1000 MB as the threshold but you can edit to whatever size is suitable. 

###
# Show Large Folders
# 
# Description: 
# Highlights a list of all folders (not subfolders) in red when the folder is over a threshold size.

##Run in PowerShell ISE with admin rights

#
# Version: 1.0
# Updated: 20231020
# Author: Julian Dalley
###

# Define the drive and threshold size (in MB) for highlighting
$drive = "C:\"
$thresholdSizeMB = 1000

# Function to format file sizes in a human-readable format
function Format-Size {
    param([double]$size)
    $units = "B", "KB", "MB", "GB", "TB"
    $unit = 0
    while ($size -ge 1KB -and $unit -lt 4) {
        $size /= 1KB
        $unit++
    }
    "{0:N2} {1}" -f $size, $units[$unit]
}

# Function to check if the current user has access to a folder
function Test-FolderPermission {
    param($folderPath)
    try {
        $null = Get-Acl $folderPath
        return $true
    }
    catch {
        return $false
    }
}

# Function to get folder size, handling "Access is denied" errors
function Get-FolderSize {
    param($folderPath)
    if (Test-FolderPermission -folderPath $folderPath) {
        $folderSize = Get-ChildItem $folderPath -File -Recurse -ErrorAction SilentlyContinue | Measure-Object -Property Length -Sum
        return $folderSize.Sum
    }
    else {
        Write-Host "Access is denied or insufficient permissions for folder: $folderPath" -ForegroundColor "Yellow"
        return 0
    }
}

# Get a list of folders and their sizes
$folderSizes = Get-ChildItem $drive -Directory | ForEach-Object {
    $folder = $_
    $folderSize = Get-FolderSize -folderPath $folder.FullName
    [PSCustomObject]@{
        Folder = $folder.FullName
        Size   = $folderSize
    }
}

# Highlight folders with size exceeding the threshold
$highlightColor = "Red"
$normalColor = "White"
$folderSizes | Where-Object { $_.Size -ge ($thresholdSizeMB * 1MB) } | ForEach-Object {
    Write-Host ("Folder: {0} - Size: {1}" -f $_.Folder, (Format-Size $_.Size)) -ForegroundColor $highlightColor
} 

# List folders below the threshold
$folderSizes | Where-Object { $_.Size -lt ($thresholdSizeMB * 1MB) } | ForEach-Object {
    Write-Host ("Folder: {0} - Size: {1}" -f $_.Folder, (Format-Size $_.Size)) -ForegroundColor $normalColor
}