PoE budget calculator

Sum switch-side device power and your reserve, then compare it with a switch’s total PoE budget.

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PoE budget calculator processes your input in this browser. Inputs and results are excluded from analytics. Recent tools save tool names, visit counts and last-visit times. Saved tools store only their names. Draft saving is optional and stays on this device; delete saved text with the draft controls. Loading text from a URL is optional and contacts that server; its URL and your IP address are visible to the server. An optional “Use in” action keeps a handoff in this tab. The next tool removes it on arrival and ignores it if more than a minute has passed.

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Powered-device count

Maximum switch-side watts per device

More inputs and assumptions

Reserve above total (%)

Available switch budget (W)

Answer

…

Sum switch-side device power and your reserve, then compare it with a switch’s total PoE budget.

More results

Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

Saved scenario

Save the current answer, then change an input to compare. This clears when you leave.

Formula and assumptions

Use manufacturer switch-side draw, including conversion and cable losses where applicable. No IEEE class, port compatibility or cable rating is inferred. A total-budget pass cannot establish per-port support.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

Scratch calculator

Check another calculation

Use +, −, ×, ÷, parentheses and %. A percentage is divided by 100. This does not change the main tool.

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Keyboard shortcuts

Updated 2026-09-26

Using PoE budget calculator

Sum switch-side device power and your reserve, then compare it with a switch’s total PoE budget.

Next: Electricity cost calculator

A worked example

Example inputs: powered-device count = 8, maximum switch-side watts per device = 15, reserve above total (%) = 20, available switch budget (w) = 150. Power budget including reserve (W) = 144.

Before you use the result

Example results for powered-device count

These examples use Maximum switch-side watts per device: 15; Reserve above total (%): 20; Available switch budget (W): 150. They are reference calculations, not recommended settings.

Powered-device count	Power budget including reserve (W)
4	72
8	144
16	288

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ToolOctopus. “PoE budget calculator.” Updated 2026-09-26. https://tooloctopus.com/poe-budget-calculator.

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