File-transfer-time calculator
Estimate how long a local file transfer will take — copying between drives, to a USB stick, or over a local network — from the file size and transfer speed.
Result
Estimated transfer time
How to use this calculator
- 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) = file size (MB) ÷ transfer speed (MB/s) — a direct division, since both are already in the same byte-based unit.
Worked example
10000MB folder, 100MB/s USB drive
Inputs: fileSize=10000, speedMBps=100
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.