---
id: mac-storage-basics.why-is-storage-lower-after-a-macos-update
url: https://storagestudio.us/faq/mac-storage-basics/why-is-storage-lower-after-a-macos-update
category: "Mac storage basics"
subcategory: "When the disk is full"
question: "Why do I have less free space right after a macOS update?"
alt_questions:
  - "storage gone after macos update"
  - "free space dropped after upgrade"
  - "system data increased after update"
  - "macos update used my space"
short_answer: "A pre-update snapshot, leftover update files and rebuilt caches and indexes. Most settles within a day or two; delete any leftover Install macOS app."
tags: ["macos update", "snapshots", "system data"]
related: ["https://storagestudio.us/faq/mac-storage-basics/what-are-local-snapshots-on-a-mac", "https://storagestudio.us/faq/mac-storage-basics/can-i-delete-old-install-macos-apps"]
applies_to: "all"
last_reviewed: 2026-10-01
---

# Why do I have less free space right after a macOS update?

After an update macOS may keep a **snapshot** taken before the update, leftover **update files**, and rebuilt **caches and indexes** (Spotlight and Photos often re-index). Most of this is temporary and settles within a day or two.

If space stays low, check for an **Install macOS** app left in Applications and release old local snapshots. See [local snapshots](https://storagestudio.us/faq/mac-storage-basics/what-are-local-snapshots-on-a-mac).