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.
From Wh Spec Back to mAh: Practical Lookups
Products like laptop batteries, power stations, and EV auxiliary packs are increasingly labeled in Wh on safety stickers and airline compliance labels. Converting back to mAh is useful when comparing with older specs or checking charger compatibility. Here are four real-world lookups:
| Product / Battery | Labeled Wh | Nominal voltage | Equivalent mAh |
|---|---|---|---|
| MacBook Air M2 battery | 52.6 Wh | 11.61 V (3S Li-Po) | 52,600 ÷ 11.61 × 1,000 ≈ 4,530 mAh |
| EcoFlow RIVER 2 portable station | 256 Wh | 25.6 V (LFP pack) | 256,000 ÷ 25.6 × 1,000 = 10,000 mAh |
| GoPro HERO12 battery | 5.5 Wh | 3.85 V (Li-Po cell) | 5,500 ÷ 3.85 × 1,000 ≈ 1,429 mAh |
| Tesla Model 3 SR 12 V aux battery | ~45 Wh | 12 V (lead-acid equivalent) | 45,000 ÷ 12 × 1,000 = 3,750 mAh |
The voltage used in the calculation must match the battery's nominal pack voltage, not the USB output or charger voltage. MacBook and laptop specs published by Apple and manufacturers list the pack voltage on the battery label itself.
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. If you are working with larger battery banks, try our Ah to kWh calculator.
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.
Divide the watt-hour figure by the pack's nominal voltage, then multiply by 1,000. For a 52 Wh battery at 11.1 V (a common 3S Li-Po pack): mAh = (52 ÷ 11.1) × 1,000 ≈ 4,685 mAh. The nominal pack voltage is usually printed on the battery label alongside the Wh figure. If you only see the Wh and cell count (e.g., 4-cell), each Li-ion cell is nominally 3.6–3.7 V, so a 4-cell pack is approximately 14.4 V nominal.