---
id: backups.why-does-the-backup-time-left-keep-changing
url: https://storagestudio.us/faq/backups/why-does-the-backup-time-left-keep-changing
category: "Backups & restore points"
subcategory: "Speed, progress and the first backup"
question: "Why does the backup's time remaining keep changing?"
alt_questions:
  - "backup ETA jumps around"
  - "time left wrong on backup"
  - "estimate keeps going up"
  - "backup estimate inaccurate"
short_answer: "The estimate follows the real transfer speed, which varies with file sizes, the cloud service and how busy your Mac is. Idle stalls are excluded, so it settles as the backup goes on."
tags: ["eta", "progress"]
related: ["https://storagestudio.us/faq/backups/how-do-i-read-backup-progress"]
applies_to: "all"
last_reviewed: 2026-10-01
---

# Why does the backup's time remaining keep changing?

Because it's worked out from the speed the backup is actually achieving, and that changes. Lots of small files move more slowly than a few big ones, cloud services vary through the day, and Storage Studio slows itself down when you're using the Mac heavily.

Stalls don't distort it: time when nothing was moving is excluded from the estimate and shown separately as idle. Over a long backup the figure settles as it gets more to go on.