Quick answer: A 2,000 W rack draws ~21 A continuous on a 120 V circuit (NEC 1.25 factor) and dumps 6,824 BTU/hr into your cooling — roughly 0.6 tons of AC capacity.
Rack Power Calculator
Calculate total rack power, circuit requirements, heat load, and generate a copyable rack diagram for documentation.
| Device | Watts | Qty | U | |
|---|---|---|---|---|
42U RACK POWER PLAN Total: 318W | Circuit: 15A @ 120V ───────────────────────────────────────────────────────────────── U | Device | Qty | Watts | Total ───────────────────────────────────────────────────────────────── 1 | Dell R730 | 1 | 250W | 250W 2 | (cont.) | | | 3 | Synology DS923+ | 1 | 35W | 35W 4 | (cont.) | | | 5 | UniFi Dream Machine | 1 | 33W | 33W ───────────────────────────────────────────────────────────────── TOTAL | | | 318W Generated by PowerSizing.com
How we calculate rack power and heat load
The calculator sums all equipment wattages, applies the NEC 80% continuous load rule to determine minimum circuit amperage, and converts total watts to BTU/hr for cooling sizing. Power density in W/U is also reported to flag high-density racks.
Heat load in BTU/hr = total watts × 3.412. A 2,000W rack generates 6,824 BTU/hr that your cooling must remove. One ton of cooling handles approximately 3.5 kW of IT load.
Frequently Asked Questions
- What PDU should I use?
- Basic PDUs provide power distribution with no monitoring. Metered PDUs show per-outlet current draw — essential for capacity planning. Switched PDUs add remote outlet control for power cycling equipment. ATS (Automatic Transfer Switch) PDUs accept dual inputs and switch to the secondary circuit on failure — required for truly redundant power.
- What is N+1 redundancy?
- N+1 means you have one more power source than you need. For rack power, N+1 means two circuits — each capable of carrying the full load — so if one circuit fails, the other takes over. Requires equipment with dual PSUs.
- How do I export this for my documentation?
- Use the Copy diagram button to paste the ASCII rack plan into Confluence, Notion, or a GitHub wiki. Use Export CSV to import the equipment list into Excel or Google Sheets for further planning.
Reviewed April 2026
Methodology and source note
PowerSizing calculators use shared formulas, documented assumptions, and current planning inputs that are summarized on the methodology page. Use these tools for first-pass planning, comparison, and sanity checks, then confirm local code, pricing, utility tariff, and installer specifics before you buy equipment.