Good Internet Speed for Online Backup — Backblaze, Carbonite, and More
Online backup services continuously upload your files to remote servers — making upload speed the critical metric. Test your upload specifically at instantspeedtest.net/.
Online Backup Speed Impact — Initial Backup Time Calculator
| Backup Size | 5 Mbps Upload | 20 Mbps Upload | 100 Mbps Upload |
|---|---|---|---|
| 100 GB | 44 hours | 11 hours | 2.2 hours |
| 500 GB | 9 days | 2.3 days | 11 hours |
| 1 TB | 18 days | 4.6 days | 22 hours |
| 5 TB | 90 days | 23 days | 4.6 days |
Why Online Backup Initial Seeding Is the Real Challenge
The initial backup upload of a full computer is the biggest challenge — not ongoing incremental backups. Backblaze, Carbonite, and CrashPlan all throttle initial backup to protect ISP bandwidth, so real-world initial backup speeds are often 5–20 Mbps regardless of your connection speed (configurable in backup client settings). After the initial seed, incremental daily backups of changed files typically use under 2 Mbps. Cable internet’s limited upload (10–20 Mbps) makes the first backup of a multi-terabyte drive take weeks. Backblaze offers physical USB drive seeding services — ship them a hard drive with your data, they import it, and your offsite backup is current from day one. See our guide on good upload speeds.
Related Guides
- What Is a Good Upload Speed?
- How to Improve Upload Speed
- Speed for Dropbox Cloud Sync
- Fiber vs Cable Internet
- Speed for NAS Backup
- Cloud Video Editing Speed
Frequently Asked Questions
Will online backup slow my internet while running?
Most backup clients have throttle settings — you can limit upload to a specific Mbps (e.g., 5 Mbps) to prevent backup from impacting other activities. Schedule heavy backup sessions overnight. Backblaze and Carbonite both have bandwidth scheduling: set maximum upload during working hours (2 Mbps) and unlimited overnight. Without throttling, an active initial backup on a cable plan saturates upload bandwidth — degrading video calls and gaming simultaneously.
Is 25 Mbps upload enough for online backup?
25 Mbps upload is excellent for ongoing incremental backups and keeps initial seeding times reasonable. A 1 TB initial backup at 25 Mbps (with client-side throttle turned off) would complete in approximately 89 hours — under 4 days. After the initial backup, daily incrementals of 10–20 GB use under 2 Mbps when scheduled overnight and complete in hours. For households with multiple computers backing up simultaneously, 25 Mbps symmetric is adequate but fiber’s 100–500 Mbps upload is ideal.