Find the twenty largest files on the drive in one command

Two questions get confused constantly. Which files are largest is answered below in one line. Which folder is largest is a different question with a different tool, because a folder of forty thousand small files never appears in a list of large files and can still be the reason the drive is full.

Explorer, with the search syntax nobody documents

Switch to Details view and add the Size column, then sort by it. Explorer's search leans on the index, so results in indexed locations appear immediately and unindexed ones trickle in, which is covered in the search index.

PowerShell, which does not depend on the index

# The twenty largest files anywhere on C. Run elevated.
Get-ChildItem C:\ -Recurse -File -Force -ErrorAction SilentlyContinue |
  Sort-Object Length -Descending | Select-Object -First 20 `
    @{n='GB';e={[math]::Round($_.Length/1GB,2)}}, LastWriteTime, FullName

Without elevation this misses every folder your account cannot read and reports no error, because -ErrorAction SilentlyContinue is what stops it stopping. The result looks complete and is not, which is the single most common way this command misleads people.

# Largest per extension, which usually names the culprit faster
Get-ChildItem C:\Users -Recurse -File -Force -EA SilentlyContinue |
  Where-Object Length -gt 50MB |
  Group-Object Extension |
  Select-Object Name, Count, @{n='GB';e={[math]::Round(($_.Group | Measure-Object Length -Sum).Sum/1GB,2)}} |
  Sort-Object GB -Descending | Select-Object -First 12

What the answers usually are

The single files that come top of the list are rarely the interesting answer, because most of them have to exist. The folder totals are where the recoverable space is, and that is what what is actually filling the C drive walks through.

For a picture rather than a list, a treemap makes the shape obvious in a way a sorted list cannot: TreeSize, WizTree and WinDirStat compared.