Portable power station capacity calculator

Set your energy budget and assumptions to find models worth checking. This is a planning scenario, not measured runtime.

Average combined load (W)Hours between reliable chargesAssumed share reaching the load (%)Reserve kept unused (%)Highest simultaneous continuous load (W)

Enable JavaScript to calculate your scenario. All guides and product records remain readable without it.

What the assumptions mean

Required nominal Wh = average watts × hours ÷ assumed delivered share ÷ remaining share after reserve. The starting 80% and 10% values are editable illustration inputs, not measurements or recommended allowances for a particular model. The delivered share includes conversion and operating losses in this simplified model.

Results apply a nominal-capacity screen. A model with a documented continuous rating below your load is excluded; an unknown regional rating remains “needs confirmation”. The planner cannot verify startup, sockets, low-load shutdown, delivered prices or appliance compatibility. It does not cover medical backup or household wiring.

How to build a load plan · Browse the full Index.

A worked load-budget example

Suppose your average combined load is 60 W and you need six hours between reliable charges. The equipment needs 360 Wh. With an assumed 80% delivered share and 10% reserve, the scenario calls for 360 ÷ 0.8 ÷ 0.9 = 500 Wh of nominal capacity. These are illustrative inputs, not measurements or a runtime promise for any model.

Vary the assumptions before making a shortlist

Keeping the same load and reserve but changing the delivered share to 70% gives about 571 Wh; at 90% it gives about 444 Wh. That spread shows why a battery label alone cannot settle runtime. Replace the average watts with figures for your equipment, and allow for periods when devices run together.

UK and EU buying checks

The arithmetic is the same in either market, but the candidate still needs the correct local sockets and voltage, a suitable documented continuous output and a compatible charging route. Check the exact regional manual. A compressor or other motor may also need a startup capability that this calculator does not model.

Can solar reduce the required battery?

It can replenish energy, but panel nameplate output is not a guaranteed recharge rate. First plan the interval without reliable charging; then consider a separate scenario with a realistic, compatible recharge route. Read the solar compatibility guide before choosing a panel.

Why is this different from the load-budget guide?

This page calculates a scenario and screens catalogue candidates. The load-budget guide explains how to gather the equipment inputs and decide which loads belong in that scenario. Use the guide first if your average load or charging interval is uncertain.