mAh to Wh Calculator - Battery Capacity Converter

Agarapu Ramesh — Editor and content reviewer
Editorially reviewed Reviewed by Agarapu Ramesh, science educator (chemistry). LinkedIn
Last reviewed: May 2026 | Standard electrical engineering formulas

mAh is charge capacity. Wh is energy. You need voltage to convert between them. A big mAh number at low voltage can still be less energy than a smaller mAh number at higher voltage.

Formula at a glance

  • Wh = mAh x V / 1000
  • mAh = Wh x 1000 / V
  • Ah = mAh / 1000

Field note: If the pack voltage is unknown, the conversion is guesswork. Find the chemistry or nameplate voltage first.

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mAh to Wh Calculator

Convert battery capacity

mAh
V
Result
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Formula

WhWh = (mAh × V) ÷ 1000

Common Battery Voltages

Battery Type Voltage
Li-ion/Li-Po 3.7V
Li-ion (full) 4.2V
NiMH/NiCd 1.2V
Alkaline AA 1.5V
Lead Acid 2V/cell

Related

Wh to mAhElectricity Bill

How to use the mAh to Wh Calculator

Use this as a runtime estimate, then discount it for battery age, discharge rate, temperature and inverter losses. Battery labels are optimistic on their best day.

Worked example

Example: 10,000 mAh at 3.7 V is 37 Wh. At 5 V output after conversion losses, usable delivered energy is lower.

Practical checks before you trust the number

  • Use nominal cell voltage, usually 3.6 V or 3.7 V for lithium-ion cells.
  • Power-bank marketing loves mAh because the number looks large.
  • Airline limits usually care about Wh, not mAh.

Common mistake

If the pack voltage is unknown, the conversion is guesswork. Find the chemistry or nameplate voltage first.

Sources and references

Related calculators

Frequently Asked Questions

Wh = (mAh × V) ÷ 1000. Convert mAh to Ah by dividing by 1000, then multiply by voltage. Example: 5000 mAh at 3.7 V → (5000 × 3.7) ÷ 1000 = 18.5 Wh. This is how power banks and laptop batteries are rated for airline carry-on limits, which are in Wh, not mAh.

Wh = (mAh × V) ÷ 1000. The voltage matters because Wh is energy and mAh is just charge. Without voltage, you can't convert. Example: a 10,000 mAh phone battery at 3.7 V → 37 Wh. The same 10,000 mAh at 11.1 V (a 3-cell laptop battery) → 111 Wh.

Wh = (10,000 × 3.7) ÷ 1000 = 37 Wh. So a typical 10,000 mAh power bank at 3.7 V Li-ion stores 37 Wh of energy. That's well under the 100 Wh airline limit, so it's allowed in carry-on. For a 20,000 mAh power bank, the figure jumps to 74 Wh — still under, but worth checking.

Because mAh is just charge (current × time), not energy. To get energy, you must multiply by voltage. A 1000 mAh battery at 1.5 V stores much less energy than the same 1000 mAh at 12 V. Voltage is the missing piece that makes the conversion meaningful.

Wh is the universal energy measure across battery chemistries. mAh depends on voltage, so comparing 3.7 V Li-ion mAh to 1.2 V NiMH mAh is misleading. Always convert to Wh first. Example: 2000 mAh Li-ion (3.7 V) = 7.4 Wh; 2000 mAh NiMH (1.2 V) = 2.4 Wh — the Li-ion has 3× the energy.

Yes. Most laptops use 11.1 V (3-cell) or 14.8 V (4-cell) Li-ion packs. A 5000 mAh, 11.1 V laptop battery = 55.5 Wh. A 7000 mAh, 14.8 V battery = 103.6 Wh — over the 100 Wh airline limit, so it requires special permission for carry-on.

Yes, this is one of the most common practical uses. Most airlines limit lithium batteries to 100 Wh in carry-on (160 Wh with permission, 300 Wh in some regions). Convert your power bank's mAh × V ÷ 1000 to get Wh, then check against airline policy before flying.