How much PoE budget do I need for my UniFi deployment?

Sum the rated wattage of every PoE device, then add 25–30% headroom for thermal derating, future expansion, and spike absorption. A fleet of twelve U7 Pro APs and eight G5 Bullet cameras pulls roughly 270W; size for 350W sustained, which means a 24-port, 400W-budget switch.

How long should a UPS hold UniFi gear up during an outage?

For most commercial sites, target 15–30 minutes of UPS runtime at full load. That covers brownouts and brief outages while providing a clean shutdown window for sustained outages. Anything longer is a generator problem, not a UPS problem.

Do I need a redundant UPS for my network rack?

For a single-rack commercial install, usually no. For multi-tenant facilities, regulated environments, or compliance-driven camera coverage, redundant UPS plus generator transfer planning is the right answer.

Why does my camera draw more power than the spec sheet says?

Cameras spike on IR activation, heater turn-on in cold weather, and recording-init bursts. Spec-sheet wattage represents typical draw, not peak. Plan for rated draw plus headroom — a deployment that "just fits" on paper often trips on a cold December night.

How is this different from the PoE calculator on Ubiquiti's site?

Ubiquiti's calculator handles total wattage. This planner handles port-class allocation, sustained-load headroom, switch standards mismatch, and UPS runtime in one panel — and exports straight to a BoM line.

Sized to ride out the actual outage.

Sum your fleet against PoE port classes and switch budget, then size a UPS for graceful shutdown — not for working through hours of dark power. Standards-aware, headroom-honest, and exports straight to a BoM line.

Open the planner →How it works

Free No sign-in Standards-aware Shareable URL

133W·12 devices

2 categories · 160W with 20% buffer · sized against PoE budget

rack design is cleanall checks pass

Switch budget fits the load with headroom, the UPS hits the 20-minute graceful-shutdown target at sustained load, and port counts leave room for the patch-panel landing. Copy the BoM and ship.

PoE devices · 2 rows · 108W draw

CategoryDeviceQty

13W·802.3af (PoE)·52W total

CategoryDeviceQty

7W·802.3af (PoE)·56W total

Include switch base-power draw (~25W)The switch itself draws ~25W on top of its PoE budget. Keep this on for honest UPS sizing.

Alternative switch · same load, different tradecompatible

Switch Standard 48 PoE

48 ports · 195W PoE budget

$589

48× PoE+

Take it with you

Three numbers decide the answer.

The planner runs PoE port-class allocation, sustained-load headroom, and UPS runtime against the same buffers drawn from real installs. Inputs come from the catalog; outputs are a shareable plan you can paste into a quote.

Standards before wattage.

Total wattage is necessary, not sufficient. A PoE++ camera will not power on through a PoE+ port even if the switch budget is otherwise fine. The planner counts ports per standard — 802.3af / at / bt-T3 / bt-T4 — and flags mismatches before the order ships.

Headroom is the difference between “works” and “works in summer”.

A switch run at 95% PoE budget on a 70°F day fails when the closet hits 90°F. The planner sizes for ~70% sustained load, leaving room for thermal derating, cable losses, and the device you forgot to count.

Runtime is for graceful shutdown, not work-through.

Target 15–30 minutes of UPS runtime: enough to ride out a flicker and to shut down cleanly during a sustained outage. Buying a UPS large enough to keep the office running for hours is a generator problem, not a UPS problem.

Standards, in one paragraph each.

Skip if you wire racks for a living. Useful if a stakeholder is about to ask why “30W of PoE” on a spec sheet isn't actually 30W out of the wall.

802.3af / PoE

The original PoE standard, delivers up to 15.4W per port. Sufficient for VoIP phones, most APs, and basic IP cameras.

802.3at / PoE+

Up to 30W per port. Most modern APs, IR cameras, and PTZ cameras live here. Default for new deployments.

802.3bt / PoE++

Type 3 delivers 60W; Type 4 delivers 90–100W. Required for high-power APs (U7 Pro Max), heated outdoor cameras, and digital signage panels.

PoE budget

The total wattage a switch can deliver across all PoE ports simultaneously. A USW-Pro-24-PoE budgets 400W across 24 ports — not per port. Plan for sustained load, not nameplate.

UPS VA vs. watts

VA (volt-amperes) is apparent power; watts is real power. A 1500VA UPS typically delivers ~900W of real load. The planner converts your wattage into the right VA class so the runtime figure matches what the UPS will actually do.

Runtime

Minutes of backup the UPS provides at the configured load. Halves roughly with each doubling of load. Target 15–30 minutes at full load — enough for a clean shutdown without paying for unnecessary battery capacity.

Four mistakes that cause “why won't this camera turn on?”

Not exotic — the four PoE/UPS issues that account for nearly every post-install support ticket. Each one is cheaper to catch on paper than at the rack.

× BUDGET-OVER

Maxing out the PoE budget on day one.

Today's twelve cameras become tomorrow's sixteen. Treating rated PoE budget as the operating budget leaves zero room for the adds, the misclick, or the summer thermal derating. Start at ~70%; let yourself grow into it.

× STANDARD-MISMATCH

Counting watts but not standards.

A 60W camera needs a 60W port, not just a switch with 60W left in the bucket. PoE++ devices on PoE+ ports don't warn — they just don't come up. Verify port-class allocation, not only total switch budget.

× NO-UPS

Skipping UPS on the “just office” rack.

Cameras, doorway readers, and the gateway you depend on for off-site backup all sit in the same rack. A two-second flicker reboots all of them. UPS is cheap insurance against the most common kind of outage, and the only kind your client will notice.

× GENERATOR-AS-UPS

Sizing a UPS to ride out hour-long outages.

UPS is for clean shutdown. Hours of runtime is what a generator is for. Size for 15–30 minutes, double-up for critical infrastructure, and price a generator separately when the risk profile actually demands it.

FAQ

Common questions about PoE budget and UPS sizing.

The phrasing varies, but most questions fall into one of these categories. If your scenario doesn't fit, that's the point at which it makes sense to talk to an engineer.

How much PoE budget do I actually need?

Sum the wattage of every device, then add 25–30% headroom. A fleet of twelve U7 Pro APs and eight G5 Bullet cameras pulls roughly 270W; size for 350W sustained — which means a 24-port, 400W-budget switch, not a 250W one running at 90%.

Can I run PoE++ devices on a PoE+ switch?

No. The device negotiates the port class on link-up and refuses to power if the port can't supply its declared standard. The wattage budget might say yes; the standards check says no. Verify both before ordering.

How long should the UPS hold my UniFi gear up?

For most commercial sites, 15–30 minutes at full load is the right target. That covers the brownouts and flicker events that make up most outages, and gives a clean shutdown window for the rest. Anything longer is a generator problem.

Do I need redundant UPS for the rack?

For a single-rack commercial install: usually no. For a multi-tenant facility, a regulated environment, or anywhere camera coverage is a compliance line: yes — redundant UPS plus a generator transfer plan. The planner outputs a single recommendation; talk to us if redundancy is on the table.

Why does my camera draw more than the spec sheet says?

Cameras spike on IR, on heater activation in cold weather, and on recording-init bursts. Spec-sheet wattage is the typical, not the peak. The planner uses the rated draw plus a buffer; it's why a deployment that “just fits” on paper trips the breaker on a December night.

Does it matter where the UPS sits in the rack?

Yes. UPS at the bottom (heaviest, cool-air intake), gear above. Don't sandwich the UPS between switches — heat output stresses the battery and shortens its life. We design rack layouts as part of every ShiftCTRL deployment for this reason.

Want this turned into a real rack design?

We'll do the site walk, finalize switch + UPS placement against the rack thermals, and hand back a written BoM with documentation, labels, and a runbook — everything your team needs to run the rack.

Talk to an engineer