Steam Deck battery life calculator and handheld runtime estimator

Estimate Steam Deck, ROG Ally, Legion Go, and handheld gaming battery life from watt-hours, system draw, and a safety buffer. Numbers are planning estimates, not manufacturer claims or guaranteed results.

How to use this estimate

Battery capacity is measured in watt-hours. Total system draw includes more than the processor power target: display, memory, storage, fans, radios, and conversion losses all matter. Measured system draw is better than using TDP alone.

Use a safety buffer because battery health, brightness, background downloads, Bluetooth accessories, and demanding game areas can shorten runtime.

Useful next step

Compare USB-C power banks, chargers, and rated cables.

Frequently asked questions

How do I estimate handheld battery life?

Divide usable battery watt-hours by estimated total system draw. The result is a planning estimate; display brightness, wireless use, battery health, and game load change runtime.

What wattage should I enter?

Use measured total system draw when available. A device TDP value alone does not include the display, memory, storage, cooling, and conversion losses.

How can I extend Steam Deck or ROG Ally battery life?

Use a stable frame cap, lower brightness, reduce the power target gradually, and lower expensive graphics effects.