GuideData center · 4 min
How much power to plan for in a data center
How to turn a rack count into a kW number for data center space (colocation). Measured draw versus the label, what power per rack changes, and why power sets your price.
The Clectiv team ·
Data center space is priced on power, not racks. Walk in with a real kW number and you set the terms of the first call. Here's how to get it.
Why power matters more than rack count#
A rack count tells a provider almost nothing. Two buyers who both say "twenty racks" can need wildly different power: one fits any building, the other only a few.
So every serious quote is priced on power, in kilowatts or megawatts (kW or MW). Start with racks and you lose a round while the provider asks for the power number. Have it on day one.
Measure what you use, don't read the label#
The most common mistake is sizing from the label on the equipment. That's the most the power supply can handle, not what the server really pulls. Size from it and you pay for power you'll never use.
Use measured draw from your current setup, plus real room to grow. No meters? Add up typical server wattage, not the maximums.
Power per rack: what it changes for you#
Power per rack (density) matters as much as your total. Same total power at a different density means a different rack count, different cooling and sometimes a different building.
In plain terms: ordinary business servers run a few kW per rack. AI and high-performance gear runs tens of kW and up. Our glossary has more.
What your density decides#
- Cooling. Ordinary racks are air-cooled. AI gear often needs liquid cooling, and not every building has it.
- Which buildings fit. Some buildings can't power or cool dense racks without a retrofit. Ask per building.
- Price. High-density and liquid-cooled space usually costs more per kW. Quote total kW without density and the quotes won't line up.
Reserved power or metered power: know which you're buying#
Ask how your power gets billed. The same rate gives very different bills under each model:
- Committed power: you pay for what you reserve, used or not. The usual model for racks and cages.
- Metered power: you pay for what you use, often on top of a reserved base.
Don't mix up building totals and rack power. Iron Mountain's biggest Manassas building carries about 96 MW. That tells you nothing about one rack, or what's free for you.
How Clectiv AI solves this#
Doing this on your own means months of chasing reps, one at a time. Every call starts from scratch, and every provider knows they're the only one in the room.
With Clectiv AI, it's days, not months. Start your project here, before you call a provider, and Clectiv AI runs the process: it goes to every provider that fits, at the same time. They know they're competing, so their best numbers come back side by side, and you choose.
You start where others finished, with 20+ years of buyer-side projects and our own data on 2,200+ buildings behind your request.
The two numbers to have before your first call#
- Total power in kW or MW, from measured draw plus real room to grow.
- Power per rack, so a provider can tell you right away whether its floor takes it.
Those two feed everything else in how to run a data center bid. Stuck on a term? Try the glossary.