Migration Data Transfer Time Calculator

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

About Migration Data Transfer Time Calculator

Bulk data migration over the network is often far slower than intuition suggests: 400 TB over a gigabit link at 60 percent usable throughput takes over two months. Physical transfer appliances ship tens of terabytes each and complete in about a week regardless of volume, which is why they exist — the crossover is usually somewhere around 10 to 20 TB per available gigabit.

Formula

Transfer time

effective throughput = link rate x usable share; days = data bits / (throughput x 86400); appliances = ceil(data / appliance capacity)

Worked example

With the default values below, Migration Data Transfer Time Calculator returns Network transfer time of 61.7. Change any input above and every figure here is recalculated in your browser.

Inputs used

Data to transferminimum 0.001 TB: 400 TB
Available bandwidthminimum 0.001 Mbps: 1,000 Mbps
Share of the link usable for migrationaccepts 1–100 %: 60 %
Capacity of a physical transfer applianceminimum 0.001 TB: 80 TB

Results

Network transfer time: 61.7 days
Effective throughput: 600 Mbps
Physical transfer appliances required: 5
Faster option: Physical appliances will be faster - 5 units plus about a week of shipping

Step by step

1Values used
2Transfer time
3Network transfer time= 61.7 days
4Effective throughput= 600 Mbps
5Physical transfer appliances required= 5
6Faster option= Physical appliances will be faster - 5 units plus about a week of shipping

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 1 decimal place, 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

Why only 60 percent of the link?

Production traffic must continue, and TCP over a long path rarely achieves full line rate without tuning. Sixty percent is an optimistic-realistic planning figure.

Can migration be incremental?

Yes, and it should be for anything large. Seed with a bulk copy or appliance, then sync deltas continuously until cutover, which reduces the final switchover window to minutes.