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Rsync Transfer Time Calculator

Work out rsync transfer time instantly with clear inputs, formula shown and shareable results.

About Rsync Transfer Time Calculator

rsync pays a per-file cost for stat, checksum comparison and protocol exchange, which dominates when transferring many small files. 800,000 files at 1.5 ms each is twenty minutes of pure overhead regardless of bandwidth, which is why streaming a tar over ssh is often far faster for a first full copy than rsync file by file.

Formula

rsync duration

data time = size bits / link rate; overhead = files x per-file cost; total = data time + overhead

Worked example

With the default values below, Rsync Transfer Time Calculator returns Total transfer time of 7,867. Change any input above and every figure here is recalculated in your browser.

Inputs used

Data to transferminimum 0.001 GB
250 GB
Link throughputminimum 0.001 Mbps
300 Mbps
Number of filesminimum 1
800,000
Per-file overheadminimum 0 ms
1.5 ms

Results

Total transfer time
7,867 s
Time moving data
6,667 s
Time spent on per-file overhead
1,200 s
Bottleneck
Bandwidth dominates - compression or a faster link will help

Step by step

  1. 1Values used
  2. 2rsync duration
  3. 3Total transfer time= 7,867 s
  4. 4Time moving data= 6,667 s
  5. 5Time spent on per-file overhead= 1,200 s
  6. 6Bottleneck= Bandwidth dominates - compression or a faster link will help

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

When is rsync the wrong tool?

For an initial bulk copy of millions of small files. Streaming tar or a filesystem-level send avoids the per-file negotiation entirely; rsync excels at subsequent incremental syncs.

How is the per-file cost reduced?

Run several rsync processes over different subdirectories in parallel, and avoid --checksum which reads every byte on both ends.

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