Power Bank Recharges
Estimate how many full recharges your portable battery can provide after accounting for real-world conversion losses.
Actual runtimes depend on cable quality, device cut-off voltages, and temperature. Use this as a planning estimate, not a guaranteed spec.
Examples
- 20,000 mAh pack → 4,500 mAh phone at 88% ⇒ 3.91 full charges
- 10,000 mAh bank → 3,000 mAh camera at 85% ⇒ 2.83 full charges
- 26,800 mAh airline-legal bank → 5,000 mAh tablet at 82% ⇒ 4.39 full charges
FAQ
Why include efficiency?
Voltage conversion, heat, and cable resistance reduce the delivered capacity. Efficiency captures these losses.
Can I enter watt-hours instead?
Yes. Convert both the power bank and device batteries to the same unit (mAh at nominal voltage) before using the calculator.
Does fast charging change the result?
Fast-charging protocols may lower efficiency by a few percentage points. Adjust the efficiency input to match your observed performance.
How should I interpret fractional charges?
A result like 3.9 means three full recharges plus a partial top-up to 90% on the fourth cycle.
Additional Information
- Usable capacity = Power bank mAh × Efficiency ÷ 100.
- High-draw devices or fast-charging protocols can lower efficiency; adjust the percentage based on your measurements.
- Convert watt-hours to milliamp-hours by dividing Wh × 1,000 by voltage (usually 3.7 V) if your bank lists Wh instead.