Backcountry Power & Battery Planner
Build a realistic power budget in watt-hours, include charging losses and your own reserve, then compare common power-bank sizes by capacity and carried weight. This is a planning aid, not a guarantee of runtime in the field.
Trip assumptions
Use conservative inputs based on your own devices and real-world usage.
Devices
Enter daily energy use directly in Wh when you know it, or estimate from battery voltage × Ah × daily fraction used.
Power plan
Actual usable energy varies by power bank, cable, device charging behavior, temperature, battery age and how often screens/radios are used. Treat this as a planning margin, not an emergency power guarantee.
Your data
Stored only in this browser. GentleTools does not receive your device list or trip plan.
Saved plans
Delete all saved power plans?
No server copy exists.
Why watt-hours beat mAh for mixed devices
mAh only makes sense at a known voltage. A phone battery, a 5 V USB output and a power bank cell may all advertise mAh at different voltages. Watt-hours put them on one energy scale, which is why this planner uses Wh internally.