PoE Power Budget Calculator for IP Cameras
Count your cameras by type, set the longest cable run, and get the PoE budget, port count and switch models that fit — with the 20% headroom every installer should keep.
Engineering tool · Formulas from IEEE 802.3af/at/bt · Updated September 2026
Calculator
Enter how many devices of each type you will power. Wattage defaults are typical datasheet peaks (IR on at night) — edit them if you have the real figures.
How the calculation works
Three numbers decide the switch: total watts, number of PoE ports, and the longest cable run.
Total load = Σ (devices × watts per device). We then add headroom (default 20%) because IR illuminators, heaters and PTZ motors draw peak power at the same time on a cold night — the moment a switch sized to the exact sum shuts ports down.
Per-port class matters as much as the total: 802.3af delivers 15.4 W at the switch (12.95 W at the camera after 100 m of cable), 802.3at/PoE+ 30 W (25.5 W), 802.3bt Type 3 60 W (51 W) and Type 4 90 W (71.3 W). A 60 W heated PTZ cannot run on an at-class port however large the total budget is.
Cable length changes the product, not just the number: 250 m PoE extend mode exists only on Fast Ethernet models and drops the port to 10 Mbps (enough for one camera stream). Beyond 250 m, plan fibre (SFP) or a mid-span industrial switch.
Typical power draw per device
Use the datasheet figure when you have it; these are the working numbers we use when sizing projects.
| Device | Typical draw | PoE class needed |
|---|---|---|
| Fixed bullet / dome / turret, IR | 4–8 W | 802.3af |
| Varifocal, full-colour or dual-light camera | 8–13 W | 802.3af / at |
| PTZ dome (no heater) | 15–25 W | 802.3at |
| PTZ with heater / wiper, laser PTZ | 40–60 W | 802.3bt |
| Wi-Fi access point, IP phone, intercom | 6–15 W | 802.3af / at |
| Solar 4G camera (self-powered) | 0 W | — |
Five rules before you order
Each one comes from a real site call-out.
- Keep 20% headroom on watts and 20% spare ports — a switch full on day one is a switch you buy twice.
- Count the night-time peak (IR on), not the daytime average printed in marketing sheets.
- Any single device above 30 W needs an 802.3bt port or a local power supply — the total budget does not help.
- Runs over 100 m: pick a Fast Ethernet model with 250 m extend mode; over 250 m: fibre or an industrial mid-span switch.
- Check the uplink: 16 cameras at 4 Mbps fit in one gigabit uplink; 4K cameras or 24+ channels justify dual gigabit or SFP fibre to the NVR.
PoE switch models by port count
The models the calculator chooses from. Budgets are total PoE output per datasheet; every port supports 802.3af/at (30 W max).
| Model | PoE ports | PoE budget | Access / extend |
|---|---|---|---|
| Atlas S402EI | 4 | 52 W | Fast Ethernet, 250 m extend |
| Atlas S4G02GFI-SFP | 4 | 52 W | Gigabit access |
| Uniarch SW-2106-LP | 4 | 60 W | Fast Ethernet, 250 m extend |
| Uniview NSW2020-6T-POE-IN | 4 | 60 W | Fast Ethernet, 250 m extend |
| Uniarch SW-2110-LP | 8 | 60 W | Fast Ethernet, 250 m extend |
| Uniview NSW2020-10T-POE-IN | 8 | 88 W | Fast Ethernet, 250 m extend |
| Atlas S802EI | 8 | 96 W | Fast Ethernet, 250 m extend |
| Uniview NSW2010-10T-POE-S-IN | 8 | 96 W | Fast Ethernet, 250 m extend |
| Atlas S802GI | 8 | 120 W | Fast Ethernet, 250 m extend |
| Atlas S802GIGFI | 8 | 120 W | Fast Ethernet, 250 m extend |
| Uniview ISW2000-8T2GP-POE-IN (industrial) | 8 | 120 W | Fast Ethernet, 250 m extend |
| Atlas S8G02GI | 8 | 120 W | Gigabit access |
| Atlas S8G02G2GFI | 8 | 120 W | Gigabit access |
| Zhongxin Shutong ZJIES1000D-P-8PGT2GB-DC (industrial DIN) | 8 | 240 W | Gigabit access |
| Uniarch SW-2218-LP | 16 | 150 W | Fast Ethernet, 250 m extend |
| Uniview NSW2020-16T2GC-LPOE-IN | 16 | 150 W | Fast Ethernet, 250 m extend |
| Atlas S1602G1GFI | 16 | 200 W | Fast Ethernet, 250 m extend |
| Atlas S16G02GI | 16 | 200 W | Gigabit access |
| Uniview NSW2020-16T2GC-POE-IN | 16 | 250 W | Fast Ethernet, 250 m extend |
| Uniarch SW-2226-LP | 24 | 250 W | Fast Ethernet, 250 m extend |
| Uniview NSW2020-24T2GC-LPOE-IN | 24 | 250 W | Fast Ethernet, 250 m extend |
| Zhongxin Shutong ZJIES1000-P-24PGT2GB | 24 | 245 W | Gigabit access |
| Atlas S2402G1GFI | 24 | 260 W | Fast Ethernet, 250 m extend |
| Atlas S24G02G2GFI | 24 | 260 W | Gigabit access |
| Uniview NSW2020-24T2GC-POE-IN | 24 | 370 W | Fast Ethernet, 250 m extend |
Questions installers ask
Short answers you can quote to your own customers.
How many watts should I plan per IP camera?
Plan 6–8 W for a fixed camera with IR, 10–13 W for varifocal, full-colour or dual-light models, 20–25 W for a PTZ and 40–60 W for a heated PTZ. Then add 20% headroom to the total.
Is the PoE budget shared across all ports?
Yes. A 16-port switch with a 150 W budget can give 30 W to five ports or about 9 W to all sixteen — not 30 W to every port at once. That is why the calculator checks both the port count and the total watts.
What happens when the budget is exceeded?
The switch cuts power to the lowest-priority ports (usually the highest numbers) and those cameras reboot in a loop at night. It looks like a camera fault and is diagnosed as one for weeks.
Can I mix 802.3af cameras and 802.3at PTZs on one switch?
Yes — every switch listed here negotiates af or at per port automatically. Just make sure the total budget covers the sum and reserve a full 30 W for each PTZ.
Do you size the switch for me if I send a camera list?
Yes. Send the model list or BOM on WhatsApp or through the inquiry list (attachments accepted) — an engineer replies within 24 hours with the switch, uplink and cabling plan.
References
Standards and vendor documents this tool is based on. Product figures come from the datasheets on each model page; confirm the exact firmware and PoE mode with us before ordering.
Not sure the numbers are right for your site?
Send the camera list and cable distances — an engineer checks the budget and replies within 24 hours with a sized recommendation.