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Disk copy time calculator

Estimate local file copy time from data size and effective transfer speed in MB/s.

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Data sizeUnitEffective MB/s

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How to use it

Estimate local copy time from data size and an effective transfer rate in MB/s. It is useful for SSD, HDD or NAS planning when you have a realistic observed copy speed and want a rough duration.

Enter the data size and choose MB, GB or TB.
Enter the effective copy speed in MB/s.
Use the displayed duration and seconds as a planning estimate.

Capacity: Decimal units
Speed: MB/s
Assumption: The entered rate remains steady
Scope: Data-transfer time estimate

100 GB at 150 MB/s takes about 11 minutes 7 seconds

Using 100,000 MB for 100 GB, dividing by 150 MB/s gives about 667 seconds, or roughly 11 minutes 7 seconds.

Many small files, antivirus scanning, encryption, USB/NAS variation and slow destination writes can increase actual time. The result assumes the entered effective speed remains steady.

Use observed speed rather than a marketing maximum

If a drive advertises 3,000 MB/s but a representative copy actually runs at 600 MB/s, entering 600 produces a much more useful estimate.

The slower side of the copy path matters

A fast source SSD copying to a slow hard drive can be limited by the destination. Use an effective rate that reflects the whole path.

Large numbers of small files add overhead

The same total capacity can take longer when it is split across hundreds of thousands of files because filesystem and metadata work occurs per item.

MB, GB and TB use decimal conversion

The estimate treats 1 GB as 1000 MB. Operating systems that display GiB-style values can show a slightly different number for the same data.

Backup jobs may have extra phases

Verification, compression, snapshots or network transfer can add time beyond the raw copy step calculated here.

Related references: Digital storage units · SI prefixes & units