---
id: freeing-space.what-is-the-on-your-fast-drive-chart
url: https://storagestudio.us/faq/freeing-space/what-is-the-on-your-fast-drive-chart
category: "Freeing up space"
subcategory: "Storage Profile, charts and Home"
question: "What does the \"On your fast drive, not this Mac\" chart show?"
alt_questions:
  - "On your fast drive chart"
  - "Why did the fast drive chart go down?"
  - "Space saved chart Storage Studio"
  - "Data moved off my Mac chart"
short_answer: "It shows how much of your data is on your fast drive instead of this Mac, measured from the drive. It goes down if you move something back, so it can fall as well as rise."
tags: ["charts", "external drive", "measurement"]
related: ["https://storagestudio.us/faq/freeing-space/what-are-the-storage-charts", "https://storagestudio.us/faq/freeing-space/why-didnt-the-chart-go-up-after-a-clean-up"]
applies_to: "all"
last_reviewed: 2026-10-01
---

# What does the "On your fast drive, not this Mac" chart show?

It shows how much of your data lives on your fast drive instead of on this Mac, measured from the drive itself. It sits under the free-space chart and shares its zoom, so you can compare the same window.

Because it's a measurement rather than a running tally, it can fall as well as rise: move something back to your Mac and the line goes down. That makes it the clearest place to see the effect of moves, while the free-space line shows everything else happening on your Mac at once. See [why the free-space chart may barely move](https://storagestudio.us/faq/freeing-space/why-didnt-the-chart-go-up-after-a-clean-up).