mAh to Wh Calculator
Convert battery capacity in milliamp-hours to energy in watt-hours. Useful for comparing power banks, EV battery packs, solar storage cells, and portable electronics on a like-for-like energy basis.
How do you convert mAh to Wh?
Multiply milliamp-hours by the battery voltage, then divide by 1000: Wh = (mAh × V) ÷ 1000. A 3000 mAh cell at 3.7 V stores (3000 × 3.7) ÷ 1000 = 11.1 Wh. Always use the battery's nominal voltage, not its fully charged voltage.
mAh to Wh Formula
Multiply the battery's capacity in mAh by its nominal voltage, then divide by 1,000 to convert milliamp-hours into amp-hours (since 1 Ah = 1,000 mAh). The result is energy in watt-hours. Always use the cell's nominal voltage — not the charging or cut-off voltage.
Common Battery Sizes — mAh to Wh
| Battery / Device | Capacity (mAh) | Voltage (V) | Energy (Wh) |
|---|---|---|---|
| Power bank (standard) | 10,000 mAh | 3.7 V | 37.00 Wh |
| Smartphone | 4,500 mAh | 3.85 V | 17.33 Wh |
| AA alkaline cell | 2,500 mAh | 1.5 V | 3.75 Wh |
| 18650 Li-ion cell | 3,000 mAh | 3.6 V | 10.80 Wh |
| Laptop (3S pack) | 5,000 mAh | 11.1 V | 55.50 Wh |
Why Convert mAh to Wh?
mAh is only meaningful when you also know the voltage. Watt-hours is the universal energy unit — it lets you compare batteries of different chemistries and voltages on equal terms.
Airlines limit carry-on batteries to 100 Wh (or 160 Wh with approval) — not mAh. Convert to check if your power bank is flight-safe.
Solar battery banks are rated in Wh or kWh. Convert your cell's mAh to Wh to calculate how many hours of load a pack can support.
EV range estimates use Wh/km. Knowing your pack's Wh capacity lets you estimate range at a given efficiency figure.
LiPo packs use different cell counts (1S–6S) and voltages. Wh lets you compare packs with different S-ratings fairly.
Capacity in Context: Named Battery Packs as Reference Points
Abstract mAh numbers are easier to interpret when anchored to familiar devices. The figures below use publicly documented nominal cell voltages to calculate Wh. These are representative values — exact specs vary by production year and region.
- Anker 737 Power Bank (24,000 mAh, 3.7 V nominal cell): 24,000 × 3.7 ÷ 1,000 = 88.8 Wh. This is below the 100 Wh threshold for carry-on batteries under IATA/FAA regulations, so it can be taken on a plane without airline pre-approval.
- Typical iPhone 15 battery (~3,877 mAh, 3.86 V nominal): 3,877 × 3.86 ÷ 1,000 ≈ 15 Wh. A 37 Wh power bank (10,000 mAh at 3.7 V) can theoretically charge it roughly 2.5 times before accounting for USB conversion losses (~85 % typical efficiency).
- Rad Power Bikes RadRunner 2 e-bike battery (14 Ah / 14,000 mAh at 48 V): 14,000 × 48 ÷ 1,000 = 672 Wh. At a typical e-bike consumption of roughly 15–20 Wh/km, this pack provides an estimated 33–45 km of range under normal conditions.
- DeWalt FLEXVOLT 9 Ah battery (9,000 mAh at 60 V nominal): 9,000 × 60 ÷ 1,000 = 540 Wh. Cordless power tool packs are rarely described in Wh on retail packaging, making this conversion essential when comparing runtimes across different brand voltage platforms.
Frequently Asked Questions
How do I convert mAh to Wh?
Multiply the milliamp-hour value by the battery voltage, then divide
by 1,000: Wh = (mAh × V) ÷ 1,000. For example, a
10,000 mAh power bank at 3.7 V holds
(10,000 × 3.7) ÷ 1,000 = 37 Wh.
Use the nominal cell voltage, not the USB output voltage.
What is the formula for mAh to Wh?
The formula is: Wh = (mAh × V) ÷ 1,000. This works
because watt-hours = amp-hours × volts, and 1 Ah = 1,000 mAh.
Always use the nominal cell voltage — for Li-ion cells this is
typically 3.6–3.7 V, not the 4.2 V peak charging voltage.
How many Wh is 10000 mAh?
It depends on the battery voltage:
- 3.7 V (Li-ion cell): 37 Wh
- 3.85 V (Li-Po / phone): 38.5 Wh
- 5 V (USB-rated label): 50 Wh
Most manufacturers use 3.7 V as the cell nominal voltage — so a 10,000 mAh pack typically holds about 37 Wh of usable energy.
What does mAh mean on a battery?
mAh stands for milliamp-hours. It measures how much electric charge a battery can store — specifically, how many milliamps of current it can deliver for one hour before depleting. A 3,000 mAh cell can supply 3,000 mA (3 A) for 1 hour, or 1,500 mA for 2 hours. However, mAh alone does not tell you total stored energy — you also need the voltage to calculate watt-hours.