Portable power · FREE TOOL

Portable Power Station Size & Runtime Calculator

Plan appliance energy, running watts and startup demand; estimate existing-station runtime and compare a small sourced manufacturer catalog.

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Your inputs

Edit the example
Ordinary plug-in appliances

Use measured or manufacturer watts. Startup total is the total during starting, not extra watts. Blank means unknown.

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2

Planning assumptions

%

Editable planning assumption. Follow the battery maker’s limits.

%

An assumption, not a measured equipment specification.

%

Adds this percentage to the energy estimate; not a state-of-charge cutoff.

W

Added once for the longest entered usage duration. Leave 0 if unmeasured; actual runtime may be lower.

Wh

Used only for an equivalent-runtime estimate, not a suitability claim.

Example estimate · editable inputs

Estimated nominal capacity needed

466.67 Wh

Appliance energy
280 Wh
Simultaneous running
70 W
Startup total
Unknown
Known startup lower bound
70 W
Existing station equivalent runtime
10.29 h
Schedule-average load
70 W

2 appliance startup value(s) unknown. Duty cycle reduces energy, not required running watts. Extra reserve is added to sizing; existing-station runtime is before that extra reserve.

A SMALL RESEARCHED SAMPLE

Compare the specifications

Three US models clustered around 1 kWh, checked 2026-11-01. This small sample does not cover the whole market or search for the cheapest product. We have not hands-on tested these products. Numerical candidates still need verification of startup and outlet constraints.

Ordinary manufacturer/source links only; no active affiliate tracking. Read our disclosure.

Your comparison requirements

Nominal energy needed
466.67 Wh
Simultaneous running
70 W
Known startup lower bound
70 W
Full startup demand
Unknown · needs verification

BEHIND THE RESULT

How the calculation works

Plan energy and output as in the Battery Backup tool. Equivalent runtime h = existing nominal Wh × usable fraction ÷ (schedule-average load W ÷ efficiency + battery-side idle W). Additional reserve affects sizing, not the displayed runtime.

Capacity in Wh, continuous output in W, startup behavior, and regional outlet compatibility are separate checks. Catalog entries are manufacturer specifications, not hands-on test results. They are ordered by nominal capacity, with no commission preference.

A worked example

A 60 W laptop and a 10 W lamp, each for 4 hours, use 280 Wh. With 80% usable capacity, 90% efficiency, 20% extra reserve and no idle draw, nominal capacity is 466.67 Wh. A 1,000 Wh station has about 10.29 equivalent hours at the 70 W average load, before extra reserve.

What this estimate can’t tell you

Equivalent runtime repeats the schedule-average load; it does not simulate each appliance’s on/off timing. Unknown startup values remain unknown. Even a numerical match requires manufacturer confirmation of surge duration, per-outlet limits, frequency and exact plug fit. Ordinary plug-in loads only; no medical life-support or whole-home integration.

Sources & methodology

Formulas are derived from the units shown. Read our methodology or report a correction. Sources reviewed 2026-11-01.