Data Centre PUE Calculator
Power usage effectiveness from total facility power and IT load. With the formula, a worked example and typical values.
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Estimate only. Not engineering or safety advice. Check the result against the applicable standard and the equipment data, and have a competent engineer review it before it is relied on. Terms of use.
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About this calculator
This page calculates PUE, DCiE and overhead from total facility power and IT equipment power. Change any value or its unit and the result updates. The steps below show the working for the default values, so you can check each line against your own method.
Limits of this calculator
A single spot reading can mislead. Use energy over a full year so seasonal cooling load is included.
Cross-check: 6 reference cases, calculated from textbook formulas coded separately from the engine by the same author, agree with this calculator. This is not an independent review.
Verification status: Engineering reference
Engineering reference. Formula and method documented and tested against separately coded reference calculations. Not yet Verified: the evidence listed on this page is still needed.
What this calculator checks
- The arithmetic of the published formula for the values you entered, in the units shown.
What remains unverified
- That the inputs suit your application. Take ratings, resistances and constants from the manufacturer data sheet or project specification.
Verification register entry
| Calculation author | Rahul Sharma (author) |
|---|---|
| Technical review | No independent technical review has been carried out |
| Individual professional approval | Not recorded |
| Formula reference | not recorded |
| Standard and edition | ISO/IEC 30134-2, 2026 Ed 2 |
| Standard review state | Public-scope screened; licensed clause review still pending |
| Scope-screening note | Defines data-centre PUE measurement, calculation and reporting. The calculator implements the basic total-facility-power / IT-equipment-power ratio; metering boundaries and reporting conditions must follow the standard. |
| Cross-check test cases | 6 reference vectors (tests/reference_vectors.json) |
| Review date | not recorded |
| Next review date | not recorded |
| Status | Engineering reference |
Needed before this calculator can be marked Verified: reviewer name, qualification and review date; licensed clause-by-clause standard review; exact formula reference; formula source (textbook or standard); next review date.
Formula
Worked example
| Input | Value |
|---|---|
| Total facility power | 1,500 kW |
| IT equipment power | 1,000 kW |
- PUE = 1,500 / 1,000 = 1.5
- DCiE = 100 / 1.5 = 66.67 %
- Overhead = 1,500 − 1,000 = 500 kW
Assumptions
- Both powers are averaged over the same period
- IT power is measured at the PDU or rack outlet
A single spot reading can mislead. Use energy over a full year so seasonal cooling load is included.
Inputs and results
| Input | Unit | Allowed or shown | Note |
|---|---|---|---|
| Total facility power | kW | greater than 0 kW | |
| IT equipment power | kW | greater than 0 kW |
| Result | Unit | Allowed or shown | Note |
|---|---|---|---|
| PUE | (number) | Shown to 2 decimal places | |
| DCiE (IT share of total, %) | (number) | Shown to 1 decimal place | |
| Overhead (cooling, losses, lighting) | kW | Shown to 1 decimal place |
How it is calculated
Each input is converted to the base unit of its quantity, the formula above is applied in the order shown in the worked example, and each result is shown in the unit you choose. Results are held at full precision and rounded only for display, except where a step selects a standard size, as the worked example shows. A value outside its allowed range is refused with a message instead of giving a result.
How the result changes with total facility power
| Total facility power (kW) | PUE | DCiE | Overhead (kW) |
|---|---|---|---|
| 1,500 | 1.5 | 66.7 | 500 |
| 3,000 | 3 | 33.3 | 2,000 |
| 6,000 | 6 | 16.7 | 5,000 |
| 15,000 | 15 | 6.7 | 14,000 |
Other inputs are the same as in the worked example above.
Standards and further reading
- EN 12464-1 (lighting of indoor workplaces)
- CIE publications on photometry
Lamp and luminaire data come from the manufacturer; the illuminance targets that apply come from your project specification and local regulation. These are named as background reading. Elecmetric does not embed clause text or rating tables, and the reviewer record for this calculator is separate from this list.
Frequently asked questions
What do I need to enter?
Enter total facility power and iT equipment power. Change the unit of a value with its selector and the result stays the same.
What does this calculator assume?
Both powers are averaged over the same period. IT power is measured at the PDU or rack outlet.
Which calculators should I use next?
Common next steps are Rack Heat Load and Airflow and UPS Battery Runtime. The related links at the bottom of this page open them.
How accurate are the results?
Every figure comes from the same tested engine as the Elecmetric calculators and is meant for estimating. 6 reference cases, calculated from textbook formulas coded separately from the engine by the same author, agree with this calculator. This is not an independent review. Check design values against the standard and the equipment data you work to.
Formula guides and reference
Longer explanations with worked examples and tables, written for the same topic.
- Cooling Formulas: Airflow and Heat Load: Cooling formulas for the airflow needed to remove heat, the temperature rise of air, watts to BTU per hour and CFM
- Energy and Cost Formulas: kWh and Payback: Energy and cost formulas for kWh from power and hours, running cost, efficiency and payback of an upgrade
More Lighting and Facilities calculatorsAll engineering calculatorsData Centre PUE in Elecmetric