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Folder Size Calculator

Analyze a selected folder locally with an interactive treemap, recursive folder totals, largest-file and extension evidence, ignore rules, age review, unreadable-item accounting and exportable reports.

Subfolder byte roll-upLargest folders + filesExtension bytes + searchFolder/file CSV + JSON

Local-only folder map · recursive totals · evidence exports

Folder Size, Treemap & Cleanup Audit Studio

Choose a folder explicitly, map where its logical bytes live, drill into heavy subfolders, search paths, review old-large files and same-size duplicate candidates, and export a read-only audit without uploading file contents.

Interactive drill-down treemapNative picker + folder-input fallbackIgnore globs + unreadable evidenceLargest folders/files + extensions + ageSame-size candidates (not hash proof)CSV · JSON · Print · numeric history

1. Select a folder locally

The native picker can walk directories and report unreadable items when supported. The folder-input fallback works more broadly but exposes files rather than a true directory handle.

Choose folder (fallback)

Ready. No folder has been read.

Browser capability truth

A website cannot silently scan a whole drive. You choose the folder. Logical file length is not the same as filesystem allocated size, compressed size-on-disk, cloud placeholder size, or deduplicated storage.

2. Scan rules

Ignore patterns — one per line or comma; *, ?, ** supported Ignore matching is case-insensitive

Ignore rules apply on the next scan. A pattern without / can match any path segment; patterns containing / match the normalized relative path.

Report controls

Search path / extMinimum row MBRows/tableReview ≥ MBOlder than days

No session baseline pinned.

Logical bytes0 B

Files0

Folders observed0

Largest file—

Unreadable0

Bytes >1 year old0 B

3. Treemap — click a folder to drill in

Rectangle area is proportional to logical bytes among the current folder's direct children. Files and folders with zero logical bytes are omitted from the map but remain in counts where the browser exposes them.

Choose a folder or load the demo.

Largest folders

Folder	Size	Files	Share	Map

Largest files

Path	Size	Ext	Modified	Share

Extensions by bytes

Extension	Bytes	Files	Share

Modified-age distribution

Modification time is metadata supplied by the browser/filesystem. It is not proof that a file is obsolete or safe to delete.

Old + large review queue

These are review candidates only. No file is deleted, moved or modified.

Path	Size	Modified	Action

Same-size candidate groups

Matching byte length is a fast triage signal, not duplicate proof. Exact duplicate detection requires content hashing/byte comparison.

File size	Count	Potential repeated bytes	Examples

Unreadable / scan errors

No scan yet.

Measurement evidence

Choose a folder or load the demo.

Evidence handoff & repeat use

How to read the report

Treemap answers “where?”

Use area to spot large direct children, then click a folder to drill deeper without losing the parent context.

Roll-up answers “how much?”

Every file contributes its logical bytes to each ancestor folder. That is why parent totals include nested files.

Errors stay visible

When native directory iteration cannot read a file, the error is listed instead of silently counting the file as zero bytes.

Cleanup stays manual

Age, size and same-size groups are evidence for review. This Studio never auto-deletes and does not claim two same-size files are duplicates.

Truth boundary: WebToolArc measures the logical byte length and metadata the browser is allowed to expose. It cannot silently scan entire drives, report filesystem allocation/slack/compression/deduplication, bypass permissions, guarantee access to cloud placeholders, prove same-size files are duplicates, or decide that an old/large file is safe to delete. The native picker and folder-input fallback expose different directory/error details.

Start with the treemap, then drill down

The fastest route to a space hog is usually visual: find the largest rectangle, open that folder, then repeat until the biggest file or nested directory becomes obvious.

Logical bytes are not “size on disk”

Browser file metadata exposes logical file length. Filesystem block allocation, sparse extents, compression, deduplication and cloud-placeholder behavior can make operating-system disk usage differ.

Use ignore rules for generated trees

Large code projects often contain node_modules, build outputs or caches. Ignore patterns let you compare the part of the tree you actually care about, but ignored directories do not contribute to the filtered total.

Review candidates are not deletion recommendations

Old-large and same-size groups narrow the audit. Verify ownership, backups, references and file contents yourself before deleting or moving anything.

Private by design

The scan runs in this browser tab. Reports can include local paths when you explicitly export them; the settings-only share link excludes paths, file names, sizes, ignore rules and history.