Data Transfer Calculator — Drive to Drive Copy Times
A data transfer calculator estimates how long copying data between devices will take, using the sustained speed of the connection instead of the manufacturer's headline number.
Quick answer: Time = data size ÷ sustained transfer rate. 500 GB from a SATA SSD to an external USB 3.2 drive at 150 MB/s takes about 56 minutes; over 1 GbE Ethernet at 112 MB/s it takes about 74 minutes.
Copy times between drives, cards and network shares — SSDs, NVMe, USB and Ethernet at their typical sustained rates.
| File size | Time |
|---|---|
| 700 MB (CD) | 1 h 44 min 10 s |
| 4.7 GB (DVD) | 42 s |
| 25 GB (Blu-ray) | 3 min 43 s |
| 50 GB | 7 min 26 s |
| 100 GB | 14 min 53 s |
| 1 TB | 2 h 28 min 49 s |
ISPs sell megabits (Mbps), browsers and file managers show megabytes (MB/s). One byte is eight bits, so a 100 Mbps line tops out around 12.5 MB/s — and that is before protocol overhead.
| USB 2.0 | ~35 MB/s sustained — 100 GB ≈ 48 min |
|---|---|
| USB 3.2 / SSD external | ~150–400 MB/s depending on the drive |
| SATA SSD internal | ~500 MB/s (limited by SATA III at 6 Gbps) |
| NVMe SSD | 1,500–7,000 MB/s depending on generation |
| 1 GbE network | ~112 MB/s usable — a 1 TB copy takes about 2.5 h |
The weakest link decides the speed
A copy is as fast as the slowest component in the chain: a fast NVMe drive writing to a USB 2.0 enclosure runs at 35 MB/s, and USB hubs share one uplink between all attached devices. Reading is usually faster than writing on the same flash, and drives slow down as their cache fills — which is why a copy starts at 400 MB/s and settles at 150 MB/s by the end.
Many small files versus few large files
Filesystem operations dominate when copying thousands of small files: budget 30–50% of the sequential rate for photo libraries, source trees or mail archives. A single 100 GB video file will run at the full sustained rate, while 100,000 four-megabyte photos over the same link can take twice as long.
Network shares and NAS boxes
1 GbE delivers about 112 MB/s of file data after overhead — the practical ceiling for most NAS units. 2.5 GbE reaches about 280 MB/s, 10 GbE about 1,100 MB/s, but the NAS disks and CPU usually become the bottleneck well before the link does. Wi-Fi adds jitter on top, so use it only for convenience transfers.
When to use this calculator
- Planning a drive migration or laptop upgrade.
- Deciding whether to buy a USB 3.2 enclosure or a Thunderbolt one.
- Checking whether a NAS copy will finish before the end of the day.
- Timing a backup window for a server or workstation.
- Choosing between network transfer and physically shipping a drive.