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InfraToolbox

Category · 2 calculators

Capacity & Spend

Compare colocation pricing models on like-for-like terms, and project when you run out of headroom.

Both calculations here are about money, and both are easy to get wrong by a five-figure margin. Colocation is priced per kilowatt or per rack, and which wins depends entirely on density; capacity projections compound, so the gap between “filling up” and “full” is far shorter than intuition suggests.

Where the usual mistakes are

  • You are billed on contracted power, not draw. Contract 5 kW per rack, average 3.5, and 30% of the power spend buys nothing. The honest comparison is cost per kilowatt actually consumed.

  • The crossover point is one division. Rack price divided by per-kW price gives the density where the two models meet. At $800 and $150 that is 5.33 kW — the most useful number to take into a negotiation.

  • The date capacity runs out is not the date to act. Procurement, lead times and commissioning add up to a year or more, and electrical gear is worse. If you hit 80% in nine months, you are already late.