File-transfer-time calculator

Estimate a local file copy or transfer time from file size and transfer speed, such as copying between drives, to USB, or over a local network; this is distinct from an internet upload or download estimate.

File sizeTransfer speed (MB/s)

Result

Estimated transfer time

How to use this tool

Enter the file size — switch units if it's given in GB.
Enter the transfer speed in MB/s (megabytes per second) — check your device or drive's rated speed, or a recent transfer's reported speed.
Read the estimated transfer time.

Assumptions

Assumes a constant transfer speed for the whole operation — real transfers often start fast and slow down (e.g. copying many small files, or a drive's cache filling up).

Technical details: what the fields mean

File size fileSize: Size of the file or folder being transferred.
Transfer speed speedMBps: Transfer speed in MB/s (megabytes per second) — this is the unit most operating systems show during a file copy, unlike network speeds which are usually quoted in Mbps (megabits).

Methodology

Time (seconds) = decimal file size (MB) ÷ transfer speed (MB/s). This estimates local copy throughput in bytes per second, not an internet connection rate in bits per second (Mbps).

Worked example

10000MB folder, 100MB/s USB drive

Inputs: File size: 10000 mb, Transfer speed: 100 MB/s

Result: 1.7 minutes

Practical guidance

Many small files transfer more slowly than one large file of the same total size, due to per-file overhead — this estimate assumes one continuous stream.

Common mistakes

Using a network speed in Mbps (megabits) directly as MB/s (megabytes) — divide Mbps by 8 first, or use the Mbps to MB/s converter.

FAQs

How long will it take to copy 10GB to a USB drive?

At 100MB/s, about 1.7 minutes under ideal conditions — many small files or an older USB standard will be slower.

Last reviewed: 2026-10-11

A local-transfer estimate assuming one continuous transfer at a constant speed. Many small files, drive caching, a shared bus, or differences between rated and sustained throughput can make a real copy slower; internet upload/download rates are a separate task.

This tool provides an indicative estimate, based on the assumptions stated above.

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