File Transfer Time Calculator
Desk-speed, not plan-speed — what a drive move costs over USB, SATA or spinning rust.
File Transfer Time Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Big-copy lane — small-file transfers plunge below any table
- Sustained rates are conventions per device class
In short: A 100 GB backup over a good USB 2.0 stick — 35 MB/s sustained — is 2,857.142857 seconds: 47 min 37 s. The same 100 GB on a USB 3.0 SSD at 350 MB/s is 285.714286 seconds, 4 min 46 s: the ten-times jump the blue port promises. The marketing lane speaks bits — a 480 Mbps USB 2.0 port promises 60.000000 MB/s and delivers about 35 after overhead; a 5 Gbps port promises 625.000000 and lands near 350.
Formula
seconds = GB × 1,000 ÷ (MB/s)
A desk transfer divides bytes by bytes: gigabytes × 1,000 over the sustained megabytes per second the device actually holds. The sustained number is the honest one — interface rates are marketed in bits and never sustained: USB 2.0's 480 Mbps promise becomes about 35 MB/s of real stick, USB 3.0's 5 Gbps about 350 on an SSD, a spinning drive tops out near 120 wherever you plug it, and a SATA SSD sits near 500 with the interface still ahead of it. Thousands of small files fall below every table here — the clock prices the big, continuous copy that tables are written for.
Worked Example
- Enter the size of the copy.
- Pick the device's sustained MB/s.
- Read the clock for the big-copy case.
- Mind the small-file plunge the table cannot price.
Defaults: 100 GB at 35 MB/s → 2,857.142857 s, 47 min 37 s. Drive the rate to 350 (a USB 3.0 SSD) → 285.714286 s, 4 min 46 s — the ten-times jump is why the blue port exists. A 500 GB clone at 120 MB/s (the drive's own cap) runs about 1 h 9 min 27 s.
Strengths & Limits Of This Model
Where this engine is strong
- Interface bits vs sustained bytes priced side by side
- The four device classes that decide every clone
Where it stops
- No caching or file-count modeling
Practical Use Cases
Drive clones
500 GB overnight or over lunch
Camera offloads
card to desk, priced
SSD upgrades
the migration window
Methodology & Editorial Standards
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
File Transfer Time Calculator — 8 Expert FAQs
8 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
Why is USB 2.0 stuck near 35 MB/s?
The interface promises 480 Mbps — 60.000000 MB/s on paper — but protocol overhead, half-duplex traffic and controller limits leave a good stick sustaining about 35. The gap is not a defect; it is the difference between a marketing rate in bits and a sustained rate in bytes.
How much faster is USB 3.0?
About ten times in practice: 350 MB/s sustained against 35, so a 100 GB backup drops from 47 min 37 s to 4 min 46 s. The interface jumped from 480 Mbps to 5 Gbps and the real world tracked the leap almost exactly.
Does a spinning drive benefit from USB 3.0?
Yes — a 3.5-inch drive sustains near 120 MB/s, which a USB 2.0 port would pin at its own 35. On USB 3.0 the drive, not the port, is the limit; the clone clock divides by 120 either way the port goes once the port is out of the way.
Why do thousands of small files transfer slower?
Every file pays metadata, open-close and cache costs; the sustained-rate table prices one big continuous stream. A folder of photos can run at a fraction of the big-file rate on the same hardware — price the big copy here and budget extra for the many-small case.
What limits a SATA SSD to about 500 MB/s?
The SATA interface itself: 6 Gbps of link becomes roughly 500–600 MB/s of real throughput after encoding overhead. NVMe drives skip SATA and ride PCIe lanes into the thousands of MB/s — which is why clone clocks differ by an order of magnitude across the same chassis.
Is the transfer rate the same reading and writing?
Rarely — writes to flash trails reads, cheap sticks plunge hardest, and drives slow as they fill. The chips here price the sustained-write case, which is the pessimistic and honest one for backups.
How do I know my device's real rate?
Time a known copy and divide: 10 GB in 293 s is about 35 MB/s. Manufacturer sheets quote the interface, reviews quote the sustained curve, and your cable, port and filesystem all lean on the result.
Is this the same as my internet download?
No — this page prices desk-to-desk over a cable; the Download Time page prices plan-to-house over the internet. They share one division and nothing else: a 1,000 Mbps plan delivers 125.000000 MB/s, slower than a decade-old USB stick.