Build a device list, allow room to grow, and check the switch power budget and PoE ports together.
Planning tool
Size your PoE budget
Count the devices, allow room to grow, then check the switches. The starting values are an editable example.
Use switch-side power allocations (PSE). Choosing a type starts at its maximum allocation, including the standard’s channel allowance. Device-side input watts (PD) are a different figure.
Minimum aggregate PoE budget
381 W
20PoE ports 16 devices + 4 spare
304.8 W allocated ÷ 0.80 usable share. Budget rounded up to a whole watt.
Port mix to confirm
12 × 802.3af · Type 1
4 × 802.3at · Type 2
Power reserve does not specify future devices. Spare ports still need the required type, speed and power when you use them. Check the budget with the intended power supplies, including any failure mode you need to support.
Check a switch you already have
Enter specifications for one PSU configuration. Use a port group where every port supports the selected type; check mixed-port switches group by group.
Complete a valid plan and both switch figures to see the checks.
These checks cover the figures entered. Confirm IEEE negotiation, model support, port assignments, cabling and environmental limits separately. Proprietary passive PoE is outside this worksheet.
Switches to review
Catalog options whose stated PoE budget and total port count meet your targets. Total ports can include unpowered ports and uplinks: confirm the actual powered-port mix, included power supplies and configuration on each product page.
Work through the details
Power & racks
PoE normal and failed-PSU budget scenarios
Compare explicit PSE allocations with documented normal and surviving switch totals.
Example inputs · Replace these with your measurements to build your plan.
PSE allocations only. PD consumption and AC input are different quantities.
Method, example and sources
Enter switch-side allocations for every endpoint group.
Keep the chosen share of the final PoE budget unused and add spare powered ports.
Compare normal and surviving budgets and powered-port counts separately.
Review per-port type, PSU configuration and shedding priorities before selecting equipment.
Worked example. Four 30 W allocations and twelve 15.4 W allocations total 304.8 W. Keeping 20% of the final budget unused requires 381 W; a stated surviving budget of 370 W misses that target.
