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Package Update Size Calculator

Work out package update size instantly with clear inputs, formula shown and shareable results.

About Package Update Size Calculator

Fleet-wide patching multiplies download volume by host count, so 840 MB of updates across 400 hosts is 336 GB pulled from the internet. A local mirror or caching proxy reduces upstream traffic to a single copy — a saving of over 99 percent — and removes the dependency on external availability during a security patch window.

Formula

Patch download volume

per host = packages x average size; total = per host x hosts; a local mirror reduces upstream traffic to one copy

Worked example

With the default values below, Package Update Size Calculator returns Total download across the fleet of 312.92 GiB. Change any input above and every figure here is recalculated in your browser.

Inputs used

Packages to updateminimum 1
240
Average package sizeminimum 0.001 MB
3.5 MB
Hosts to updateminimum 1
400
Available bandwidth to the mirrorminimum 0.001 Mbps
500 Mbps

Results

Total download across the fleet
312.92 GiB
Download per host
801.09 MiB
Time to pull everything from upstream
5,376 s
Upstream traffic saved by a local mirror
99.75%

Step by step

  1. 1Values used
  2. 2Patch download volume
  3. 3Total download across the fleet= 336,000,000,000
  4. 4Download per host= 840,000,000
  5. 5Time to pull everything from upstream= 5,376 s
  6. 6Upstream traffic saved by a local mirror= 99.75

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 2 decimal places, 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

Is a full mirror or a caching proxy better?

A caching proxy such as apt-cacher-ng is simpler and only stores what is requested. A full mirror gives predictable content and works offline but consumes far more storage.

Should all hosts patch simultaneously?

No. Stagger them so a bad package does not break the estate at once, and so the mirror and network are not saturated.

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