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Server Consolidation Ratio Calculator

Work out server consolidation ratio instantly with clear inputs, formula shown and shareable results.

About Server Consolidation Ratio Calculator

Consolidation gains come from two sources: raising utilisation from the typical 10 to 15 percent of dedicated physical servers to 60 or 70 percent on shared hosts, and from newer hardware being several times more capable per socket. Multiplying both gives ratios of 20:1 or higher, which is why virtualisation displaced one-application-per-server so completely.

Formula

Consolidation

total demand = servers x current utilisation; capacity per new host = capacity multiplier x target utilisation; new hosts = ceil(demand / capacity per host)

Worked example

With the default values below, Server Consolidation Ratio Calculator returns Consolidation ratio of 20.0. Change any input above and every figure here is recalculated in your browser.

Inputs used

Existing physical serversminimum 1
180
Average CPU utilisationaccepts 0.1–100 %
12 %
Target utilisation on new hostsaccepts 1–100 %
65 %
New host capacity versus oldaccepts 1–50 x
4 x

Results

Consolidation ratio
20.0 :1
New hosts required
9
Physical servers eliminated
171
Aggregate demand in old-server units
21.6

Step by step

  1. 1Values used
  2. 2Consolidation
  3. 3Consolidation ratio= 20.0 :1
  4. 4New hosts required= 9
  5. 5Physical servers eliminated= 171
  6. 6Aggregate demand in old-server units= 21.6

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 not target 90 percent utilisation?

Headroom is needed for bursts, for host failure so surviving hosts can absorb the load, and for maintenance. Sixty to seventy percent is the usual planning target.

Does CPU utilisation alone determine the ratio?

No. Memory is frequently the binding constraint, and licensing, I/O and network bandwidth can all bind before CPU does.

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