Wh to mAh Calculator
Convert watt-hours to milliamp-hours for any battery voltage.
How do you convert Wh to mAh?
Multiply watt-hours by 1000, then divide by the battery voltage: mAh = (Wh × 1000) ÷ V. A 100 Wh power bank at 3.7 V holds (100 × 1000) ÷ 3.7 = 27,027 mAh. Use the nominal cell voltage (often 3.7 V), which is why a bank's true capacity differs from its rating at 5 V.
Wh to mAh Formula
Watt-hours measure energy. mAh measure electric charge. Since energy = charge × voltage (E = Q × V), we can isolate charge: Q = E ÷ V. Converting units: because 1 Ah = 1,000 mAh and 1 Wh = 1 W × 1 h, the formula becomes mAh = (Wh × 1,000) ÷ V.
Common Battery Wh to mAh Conversion
| Device | Capacity (Wh) | Voltage (V) | Approx. mAh |
|---|---|---|---|
| iPhone 15 | 13.6 Wh | 3.79 V | ~3,589 mAh |
| iPhone 15 Pro Max | 17.6 Wh | 3.79 V | ~4,643 mAh |
| Samsung Galaxy S24 | 15.6 Wh | 3.88 V | ~4,021 mAh |
| iPad Air (M2) | 35.9 Wh | 7.74 V | ~4,639 mAh |
| MacBook Air M2 | 52.6 Wh | 11.1 V | ~4,738 mAh |
| MacBook Pro 14" | 69.6 Wh | 11.36 V | ~6,127 mAh |
| Nintendo Switch | 16.0 Wh | 3.7 V | ~4,324 mAh |
| USB Power Bank | 36 Wh | 3.7 V | ~9,730 mAh |
Capacity figures are approximate; actual rated mAh may differ from cell voltage-based calculations due to manufacturer rounding and discharge curves.
Frequently Asked Questions
mAh = (Wh × 1,000) ÷ V. Multiply watt-hours by 1,000 and divide by the nominal battery voltage. Example: 10 Wh at 3.7 V = (10 × 1,000) ÷ 3.7 = 2,702.7 mAh.
(10 × 1,000) ÷ 3.7 = 2,702.70 mAh. This is a typical small Li-ion cell.
mAh (milliamp-hours) measures electric charge capacity — how much current a battery can deliver over time. Wh (watt-hours) measures energy, which accounts for both charge and voltage. A 3,000 mAh cell at 3.7 V stores 3,000 × 3.7 ÷ 1,000 = 11.1 Wh. Wh is more useful for comparing batteries at different voltages, while mAh is more common on product labels.
Because energy (Wh) depends on both charge and voltage: E = Q × V. Without knowing the voltage, you cannot determine how many milliamp-hours the energy represents. The same 10 Wh at 5 V = 2,000 mAh, but at 3.7 V = 2,702.7 mAh.