Skip to main content

AV rack heat load & power calculator

Size HVAC cooling, electrical breakers, UPS, and rack space for AV and IT equipment racks. Each row tracks both typical and max wattage — HVAC and breaker sizing use the max (worst case + headroom + NEC derate), while operational power-draw view shows typical. Pick devices from a preset library (~80 common products) or enter custom values; max defaults to typical × 1.3 (or × 2.5 for amplifiers) when not on the spec sheet. Live results update as you edit.

⚠ Disclaimer This tool is provided as-is, for educational and planning purposes only. Sizing estimates — always validate against actual equipment nameplates, applicable codes (NEC / AS/NZS / IEC), and qualified electrical / mechanical engineering review before procurement or installation. The Tech Space makes no warranty and accepts no liability for any loss arising from use. Full disclaimer →

Settings

Used for amp + breaker calc
Safety margin above calc load
Typical music / speech: 30–40%
Reserved RU + power capacity

Quick start templates

Equipment list

Results

Recommendations

How the math works

Note For most AV and IT equipment, essentially all consumed electrical power becomes heat — what doesn't drive moving parts or sound waves is dissipated as heat into the room. So total wattage is also (very closely) the total BTU/hr you need to remove. The conversion factor is exactly 1 W = 3.412 BTU/hr.
Important — amplifier duty cycle Audio amplifier nameplate wattage is the maximum draw — sustained only at full power into all channels. Real-world music or speech reproduction draws 25–40% of nameplate on average. This calculator multiplies amplifier rows by the duty cycle setting to avoid wildly oversizing your HVAC and breakers. PA-system designs that need pink-noise margin should set duty to 50–70%.
Important — NEC 80% rule (US) For continuous loads (≥ 3 hours of operation, which AV racks usually are), US NEC requires the circuit be sized for 125% of the load. Equivalently, you can only continuously load a breaker to 80% of its rating. The calculator already applies this when recommending breaker size on 120V / 208V settings. AS/NZS 3000 (Australia) has similar conservative practice but no formal 80% rule — the recommendations are still good practice.
Tip Add a 1U gap between heat-generating devices (amps, codecs, switches) for airflow. Hot air rises — stack heat-light devices (PDU, patch panels, cable management) low and heat-heavy devices high. For racks with passive ventilation only, expect to lose another \~10°C / 18°F of cooling margin.

Reference

Conversion factors

  • 1 W = 3.412 BTU/hr
  • 1 kW = 3,412 BTU/hr
  • 12,000 BTU/hr = 1 ton of cooling
  • 1 ton = 3.517 kW of thermal load
  • Amps (A) = Watts / Volts (resistive / PF=1)

Common circuit sizes

  • 10 A @ 230V = 2.3 kW — 1.84 kW continuous
  • 15 A @ 230V = 3.45 kW — 2.76 kW continuous
  • 20 A @ 230V = 4.6 kW — 3.68 kW continuous
  • 32 A @ 230V = 7.36 kW — 5.89 kW continuous
  • 15 A @ 120V = 1.8 kW — 1.44 kW continuous
  • 20 A @ 120V = 2.4 kW — 1.92 kW continuous

PoE budgets

  • Class 0–3 (PoE 802.3af) — up to 15.4 W per port
  • Class 4 (PoE+ 802.3at) — up to 30 W per port
  • Class 5–6 (PoE++ 802.3bt Type 3) — up to 60 W per port
  • Class 7–8 (PoE++ 802.3bt Type 4) — up to 90 W per port
  • Switch total PoE budget is shared across all ports

Rack sizes

  • 1U = 44.45 mm / 1.75"
  • Wall-mount: 6U, 9U, 12U typical
  • Half-height floor: 18U, 24U, 27U
  • Full-height floor: 36U, 42U, 45U, 48U
  • Server-room rack: 42U most common, plus 1–2U for cable management at top + 1U PDU