Rules of thumb for acres per MW hide four inputs. Change two of them and the answer halves.
Land per MW is the building footprint, the generator yard and the substation, grossed up for the share of the site you can actually build on, divided by the IT load. An illustrative 100 MW single-storey campus at 150 watts per square foot of white space needs 68.1 acres, or 0.68 acres per MW. Build two storeys and it falls to 40.3 acres; pack liquid-cooled AI halls at 300 watts per square foot on two storeys and it is 26.4.
Worked in full in The Data Center Development Handbook by Julian R. Sterling, with every figure reproduced in a free workbook.See the book on Amazon →
All inputs are illustrative. Density is measured on white space, the data hall floor where the racks stand, and the IT load is the critical load the tenant leases.
| Input | Value |
|---|---|
| Critical IT load | 100 MW |
| White space density | 150 W per sq ft |
| Gross building area / white space | 2.0 |
| Storeys | 1 |
| Peak PUE (sizes the generators) | 1.35 |
| Generator rating | 3.0 MW |
| Redundancy | one spare per block of 5 |
| Yard area per generator, with tank and clearance | 1,500 sq ft |
| On-site substation | 5.0 acres |
| Buildable share of the site | 55% |
The gross-to-white ratio carries the electrical rooms, UPS and battery rooms, mechanical plant, loading docks and offices. The buildable share is what is left after access roads, parking, setbacks from the boundary, stormwater ponds and landscaping. Both vary by jurisdiction and design, and both matter more than most people expect.
White space = IT load / density = 100,000,000 W / 150 = 666,667 sq ft (6,667 sq ft per MW)
Gross building area = 666,667 × 2.0 = 1,333,333 sq ft
Footprint = gross area / storeys = 1,333,333 / 1 = 1,333,333 sq ft, or 30.6 acres
Excel: =IT_MW*1e6/W_per_sqft*Gross_to_white/Storeys/43560
One acre is 43,560 square feet. The building alone, on one floor, already takes 30.6 acres before anything else is placed on the site.
Facility peak load = 100 MW × 1.35 = 135 MW
Generators = 135 / 3.0 = 45 running, plus 9 spares (one per block of 5) = 54
Generator yard = 54 × 1,500 = 81,000 sq ft, or 1.9 acres
Substation = 5.0 acres = 217,800 sq ft
Hard area = 1,333,333 + 81,000 + 217,800 = 1,632,133 sq ft (37.5 acres)
The generators are sized on facility load, not IT load, because cooling has to run on backup power too. That is why the peak PUE appears in a land calculation.
Site area = hard area / buildable share = 1,632,133 / 55% = 2,967,515 sq ft
= 2,967,515 / 43,560 = 68.1 acres (27.6 hectares)
Acres per MW = 68.1 / 100 = 0.68, or 1.47 MW per acre
Roads, setbacks and stormwater take 30.6 acres, as much as the building. The footprint is 44.9 per cent of the site. In hectares the campus needs 0.276 per MW.
| Use | Acres |
|---|---|
| Building footprint | 30.6 |
| Generator yard | 1.9 |
| Substation | 5.0 |
| Roads, parking, setbacks, stormwater | 30.6 |
| Site | 68.1 |
Two inputs dominate: watts per square foot and the number of storeys. The table holds everything else constant, including the 5 acre substation.
| W per sq ft of white space | 1 storey | 2 storeys | 3 storeys |
|---|---|---|---|
| 100 | 0.96 | 0.54 | 0.40 |
| 150 | 0.68 | 0.40 | 0.31 |
| 300 | 0.40 | 0.26 | 0.22 |
Going from 100 to 300 watts per square foot cuts white space per MW from 10,000 to 3,333 square feet, but land per MW falls less than threefold, because the substation, the generator yard and the setbacks do not get denser. A liquid-cooled AI campus on two storeys still needs 26.4 acres for 100 MW.
Campus size works the same way. Holding the substation at 5 acres:
| IT MW | Site, acres | Acres per MW | Substation, % of hard area |
|---|---|---|---|
| 20 | 20.9 | 1.05 | 43.5 |
| 100 | 68.1 | 0.68 | 13.3 |
| 300 | 186.2 | 0.62 | 4.9 |
In practice a 20 MW building may take a smaller substation, or none, if it connects at distribution voltage. The point is the direction: fixed site uses make small sites land-hungry per MW, and a rule of thumb quoted from hyperscale campuses understates what an edge site needs.
At an illustrative $250,000 an acre, the 68.1 acres cost $17.0m, or $170,312 per MW. Against a turnkey build of $11.0m per MW, the figure the book's chapter 13 case uses, land is 1.55 per cent of the cost. Doubling the land price moves the total by about one and a half points. Losing a year to a grid connection moves it by far more. That is the economic reason site selection starts with power and treats acreage as a constraint to check, not a cost to optimise.
Dividing the hard area by the IT load and stopping there. That gives 0.37 acres per MW instead of 0.68, because it ignores the 45 per cent of the site that can carry no building. A developer who options land on that basis finds, at master planning, that the parcel holds just over half the megawatts the power study assumed, and the scarce asset, the grid allocation, is stranded on a site too small to use it. The reverse error is to size land on the utility connection rather than the IT load: a grid connection is the IT load times the peak PUE, and the land follows the building, not the meter. How PUE turns a connection into leasable capacity is worked in how much leasable IT capacity a higher PUE costs, and the build cost per MW the land sits beside in how much a data centre costs to build per MW.
The book's underwrite of a 180 MW site, with every input live, is in the free workbook for this case.
Invert acres per MW. The illustrative single-storey campus at 150 W per sq ft of white space needs 0.68 acres per MW, so one acre carries about 1.47 MW of IT load. Two storeys raise that to 2.5 MW per acre (0.40 acres per MW), and liquid-cooled AI halls at 300 W per sq ft on three storeys to about 4.6 MW (0.22 acres per MW).
Because the substation, the access roads and the setbacks do not shrink with the load. Holding a 5 acre substation constant, a 20 MW building needs 1.05 acres per MW, the 100 MW campus 0.68 and a 300 MW campus 0.62. In the 20 MW case the substation is 43.5 per cent of the hard area; at 300 MW it is 4.9 per cent.
Usually very little. At an illustrative $250,000 an acre, the 68.1 acre campus costs $17.0m, or $170,312 per MW, against a turnkey build of $11.0m per MW: 1.55 per cent. That is why sites are chosen for power and fibre first and land price last.
This article is one calculation from The Data Center Development Handbook. The book takes the same case from first principles to the decision, chapter by chapter, and every figure it prints is a live formula in the free companion workbooks.
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