Milliamp-Hours to Watt-Hours Converter (mAh to Wh & Battery Energy

Milliamp-Hours (mAh) to Watt-Hours (Wh), Battery Voltage & Airline Rules

Milliamp-Hours measure electric charge capacity, while Watt-Hours measure true stored electrical energy:

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• Universal mAh to Wh Conversion Formula**:

E_Wh = Capacity (mAh) × V_nominal1,000 = Capacity (Ah) × V_nominal

Capacity (mAh) = E_Wh × 1,000V_nominal

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• Why Voltage Matters (The mAh Comparison Trap)**:

• Two batteries with the exact same 10,000 mAh rating store radically different energy amounts if their voltages differ:

• Smartphone Battery (3.7V): (10,000 × 3.7) / 1,000 = 37.0 Wh

• Drone LiPo Battery (14.8V): (10,000 × 14.8) / 1,000 = 148.0 Wh (4× more energy!)

• E-Bike Battery Pack (36.0V): (10,000 × 36.0) / 1,000 = 360.0 Wh (9.7× more energy!)

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• TSA & FAA Airline Carry-On Regulations (49 CFR 175.10)**:

• 100 Wh: ALLOWED in unlimited quantities in carry-on baggage (never checked baggage).

• 100 to 160 Wh: RESTRICTED (Requires prior airline approval; max 2 spare batteries per passenger).

• > 160 Wh: PROHIBITED on commercial passenger aircraft (must ship via certified HazMat cargo).

How to Use This Calculator

Enter your Battery Capacity (Milliamp-Hours / mAh) (e.g. 20000 in mAh), Nominal Battery Voltage (Volts / V) (e.g. 3.7 for standard Lithium-Ion in V), Battery Chemistry / Nominal Voltage Standard — choose from Lithium-Ion / Li-Po Cell (3.7V Nominal), Lithium Iron Phosphate (LiFePO4 - 3.2V Nominal), Lead-Acid Sealed / AGM (12.0V Nominal), and Battery & Power Bank Benchmark — choose from Custom mAh & Voltage, 5,000 mAh Smartphone Battery (3.7V) → 18.50 Wh, 20,000 mAh Travel Power Bank (3.7V) → 74.00 Wh (TSA Approved). Results update instantly as you type — adjust any value to compare scenarios.

The Formula

Convert mAh to Wh: Wh = (mAh * V) / 1000

Worked Example

A traveler taking a 26,800 mAh power bank on an international flight calculates Wh = / 1,000 = 99.16 Wh, confirming to airport security that the battery is under the 100 Wh TSA limit.

Understanding Your Result

Unit conversion precision: round to the same number of significant figures as your original measurement. Converting 6 feet to meters gives 1.8288 m — but if your measurement was approximate (±1 inch), expressing more than 2 decimal places is false precision. For international trade and technical specifications, SI units (meters, kilograms, liters) are the standard. US customary units (feet, pounds, gallons) differ from Imperial UK units: 1 US gallon = 3.785 L vs. 1 UK gallon = 4.546 L.