Backing up your computer is an important data protection task that many of us put off or forget to do regularly. However, consistently backing up your files to an external hard drive can save you from data loss disasters down the road. In this article, we’ll provide a comprehensive overview of the backup process – from typical backup sizes and connection types, to software, network backups, and best practices.
Understanding how long it takes to fully back up your computer is useful for setting proper expectations and planning your backups accordingly. With the right preparation and information, you can implement a regular backup routine that works with your schedule. By the end of this guide, you’ll have estimates for how long your backups could take based on your specific computer setup.
Factors That Affect Backup Time
The most important factors that determine how long it takes to back up a computer to an external drive are the computer’s specs, the external drive’s specs, and the amount of data being copied.
On the computer side, CPU speed, RAM capacity, and whether you have an HDD or SSD all play a role. Faster processors and more RAM allow data to be read from the internal drive and written to the external drive more quickly. SSDs have much faster read/write speeds than traditional HDDs, which reduces backup time.
For the external drive, the main factors are the connection type and transfer speed. USB 2.0 has a maximum transfer speed of 60MB/s, while USB 3.0 is over 10 times faster at 625MB/s. USB-C and Thunderbolt connections offer even faster potential speeds. In addition, solid-state external drives are faster for backups than mechanical hard drives.1
So in general, backing up a computer with a fast processor, lots of RAM, and an SSD to an external SSD connected via USB 3.0 or better will be much faster than an old mechanical hard drive computer backing up over USB 2.0.
Typical Backup Sizes
When estimating how long a backup will take, it’s important to have a sense of how large your files are. Here are some typical sizes for common file types:
Documents:
- Word documents (DOCX) are usually between 4-8KB, though large documents with images can be larger (Average File Sizes).
- PDF files range from 18-20KB for text-based documents up to multiple MB for files with high resolution images (How Big is a Gig?).
Photos:
- JPEGs are typically 1.5-2MB per photo (How Big is a Gig?).
- RAW photo files are larger, around 10-80MB each depending on the camera (RAW File Size Comparison).
Music:
- MP3 songs are about 4MB per song on average (How Big is a Gig?).
- Uncompressed music like WAV files are much larger, around 50MB per song.
Program and System Files:
- The Windows 10 operating system requires around 20-35GB of disk space.
- Individual program installation files range from under 100MB up to multiple GB for games and creative suites.
Knowing typical file sizes helps estimate how long backups will take based on the amount and types of data being copied.
Connection Types
The speed at which a backup occurs depends largely on the connection type between the computer and the external drive. Some key connection types and their typical maximum speeds include:
- USB 2.0 – Up to 480 Mbps (60 MB/s) [1]
- USB 3.0 – Up to 5 Gbps (640 MB/s) [2]
- USB 3.1 – Up to 10 Gbps (1,250 MB/s)
- eSATA – Up to 6 Gbps (750 MB/s) [1]
- Thunderbolt – Up to 20 Gbps (2,500 MB/s) [2]
As you can see, USB 2.0 is the slowest interface, while Thunderbolt is the fastest. Upgrading to a faster connection type like USB 3.0, eSATA, or Thunderbolt can significantly speed up transfer rates and backup times compared to older USB 2.0.
Desktop vs Laptop Backups
Desktop computers tend to have larger storage capacities than laptops. Most desktops use 3.5″ HDDs ranging from 500GB to multiple terabytes, with higher end models using SSDs up to 4TB or more (1). Laptops typically max out around 2TB for HDDs and 1TB for SSDs, since they are limited to smaller 2.5″ drives. However, laptops have the advantage of supporting faster solid state drives (SSDs), while most desktops still rely on traditional hard disk drives (HDDs) (2).
This means laptop backups may be faster despite the smaller drive sizes. A 256GB SSD can backup as fast as 500MB/s, while a 4TB desktop HDD maxes out around 150MB/s. So if speed is the priority, a laptop with an SSD will significantly outpace a desktop HDD backup. Desktops compensate by offering more raw storage capacity, which is ideal for large media libraries, games, or other disk-heavy use cases (3).
In summary, desktops provide more backup storage potential, while laptops can leverage SSD speeds for faster backups of a smaller storage footprint.
Backup Software
Using dedicated backup software can greatly improve the speed and reliability of backups compared to manual copy and paste. Backup software typically includes compression and incremental backup capabilities that reduce the amount of data needing to be copied each time. Compression reduces file sizes while incremental backups only copy new or changed files since the last backup.
According to PCWorld, some of the top backup software like R-Drive Image and Acronis Cyber Protect Home Office use advanced compression that can “shrink backup image sizes by up to 70%.” This compression significantly speeds up backups by reducing the amount of data transferred.
Incremental backups provide another major speed advantage by only backing up new or changed files after the initial full backup. PCMag notes popular backup software like IDrive and Backblaze use incremental backups to “speed up the backup process after the initial backup.”
Backup software also automates the backup process with scheduling features. Most backup software allows you to set a backup schedule rather than having to manually run backups. For example, Acronis and IDrive allow setting hourly, daily, weekly or monthly automated backups. Automating backups ensures they happen consistently without user effort.
Backing Up Over Network
When backing up over a network, whether to network attached storage (NAS) or the cloud, the speed will depend heavily on your network connection.
For NAS devices connected via Ethernet, speeds can reach up to 1 Gbit/s (125 MB/s) on a gigabit network, which is much faster than USB 2.0 but comparable to USB 3.0 speeds. According to some users testing NAS transfer speeds, they achieved 70-90 MB/s over USB 3.0 versus 60-80 MB/s on a gigabit network to their NAS device [1].
For cloud backups over the internet, speeds are limited by your internet upload bandwidth. On a typical consumer cable internet plan with 10 Mbps upload, you can expect maximum speeds of around 1-2 MB/s for cloud backups. Fiber internet plans with higher upload speeds will back up faster.
In either case, network transfers are limited by the slowest link – the network switch, the network cables, the NAS/cloud server’s network interface. Using modern gigabit network components will maximize transfer speeds to NAS or the cloud.
Recommended Backup Practices
When it comes to backing up your computer, experts recommend following certain best practices to ensure your data is properly protected and available when needed. Some key recommendations include:
Frequency of Backups: How often you back up your computer depends on how much new or changing data you have. For most home users, backing up once a week is usually sufficient according to Proactive Information Services. However, backing up daily or even multiple times per day is ideal if you are regularly creating or editing files. The 3-2-1 backup strategy recommends maintaining at least 3 total copies of your data, with 2 local backups and 1 offsite/cloud backup.
Automating Backups: Setting up automated backups on a schedule is highly recommended, as this takes the responsibility off you to remember to manually backup regularly. Most backup software like Apple Time Machine or Windows Backup allow automating backups daily, weekly or monthly. You can also set calendar reminders as a fallback.
Testing Restores: An important but often neglected practice is periodically testing that you can successfully restore from a backup, to ensure your backup files are not corrupted and will be there when you need them. You should test restoring different file types and from different backup dates at least once or twice a year.TechTarget recommends after any major system changes as well.
Estimating Total Backup Time
Putting together all the factors discussed so far, we can come up with some estimates for how long a full backup to an external drive might take.
Some key factors to consider:
- Total size of data being backed up
- Speed of connection between computer and backup drive
- Whether compression is enabled in the backup software
- Whether the backup is done locally or over a network
- Type of computer being backed up (desktop or laptop)
Here’s an example calculation for a typical laptop backup scenario:
- Total data size: 100GB
- Connection speed: USB 3.0 (up to 5 Gbps theoretical max)
- Compression enabled
- Local USB backup
- Laptop hard drive speed: 5400 RPM
In this case, we might expect the 100GB backup to take around 30-60 minutes. The relatively slow laptop hard drive will limit the read speed. Compression may cut down the total transfer size. And USB 3.0 provides reasonably fast transfer speeds to the external drive.
As another example, backing up a 2TB desktop over gigabit ethernet could take 6 hours or more. The much larger data size and network bottleneck will drag out the process. But enabling compression can help.
There are many backup time calculator tools available to help estimate durations based on your specific circumstances. But the examples above give a rough idea of typical backup times.
Conclusion
In summary, there are many factors that affect how long it takes to back up a computer to an external drive, including:
- The amount of data being backed up
- The speed of the external drive connection (USB 2.0 vs 3.0, Thunderbolt, etc.)
- Whether you are backing up a desktop or laptop
- The backup software being used
- If backing up over a network, the network speed
For individual computer users, an initial full backup of a drive may take several hours depending on the drive size. After that, incremental backups of changed files can be much faster. USB 3.0, Thunderbolt and SSD drives can also accelerate backups.
To learn more, readers may want to consult their backup software documentation, read reviews of backup drives, and research backup best practices online.