Watt-Hour (Wh) Battery Capacity Calculator

Convert mAh to Wh and check battery compliance for air travel (TSA/FAA/EASA rules). Essential for power banks, drones, and laptops.

User Rating 0.0 ★★★★★
Total Usage 1 times
Category Electronics
Common: 3.7V (Li-ion), 1.2V (NiMH), 1.5V (Alkaline)
Is this tool helpful?

Your feedback helps us improve.

★ ★ ★ ★ ★

About

Air travel regulations regarding lithium-ion batteries are strict. Security agencies like the TSA (USA), EASA (Europe), and CAAC (China) limit the size of batteries allowed in carry-on luggage, typically capped at 100Wh (Watt-hours) per battery without approval, and strictly prohibiting loose lithium batteries in checked bags. However, most consumer electronics especially power banks and camera batteries are labeled in milliamp-hours (mAh), not Watt-hours.

This calculator bridges that gap. It converts your battery's voltage and capacity (mAh) into Watt-hours (Wh) to verify compliance with flight safety rules. It also estimates the effective run time for devices, accounting for energy conversion efficiency, which is crucial for photographers and travelers relying on portable power.

battery calculator mAh to Wh TSA battery limit power bank allowed on plane watt hour formula

Formulas

The relationship between electric charge, voltage, and energy is defined by the formula:

E(Wh) = Q(mAh) × V(volts)1000

To reverse the calculation (calculating required mAh from a known Wh limit):

Q(mAh) = E(Wh) × 1000V(volts)

Reference Data

Device / Battery TypeStandard Voltage (V)Typical CapacityWatt-Hours (Wh)Carry-On Status
AA Alkaline Battery1.5 V2,500 mAh~3.75 WhAllowed
18650 Li-ion Cell3.7 V3,000 mAh11.1 WhAllowed
Smartphone (Average)3.8 V4,000 mAh15.2 WhAllowed
Small Power Bank3.7 V10,000 mAh37.0 WhAllowed
Laptop (MacBook Pro 16)11.4 V8,700 mAh99.6 WhMax Allowed
Large Power Bank3.7 V26,800 mAh99.16 WhAllowed
Drone Battery (Mavic 2)15.4 V3,850 mAh59.29 WhAllowed
Large Drone (Inspire 2)22.8 V4,280 mAh97.58 WhAllowed
E-Bike Battery (Small)36.0 V10,000 mAh360 WhPROHIBITED
Car Battery (Lead Acid)12.0 V50,000 mAh600 WhPROHIBITED

Frequently Asked Questions

Most airlines and safety agencies (TSA, FAA, EASA) allow lithium-ion batteries up to 100Wh in carry-on luggage without prior approval. Batteries between 101Wh and 160Wh usually require airline approval (maximum 2 spares). Batteries over 160Wh are generally prohibited on passenger aircraft.
Capacity in mAh only measures the electric charge. Watt-hours measure the actual energy. A 10,000 mAh battery at 3.7V (standard phone power bank) has 37Wh, but a 10,000 mAh battery at 12V (UPS or tool battery) has 120Wh. The higher voltage battery stores much more energy despite having the same 'mAh' rating.
No. Loose lithium batteries and power banks are strictly prohibited in checked luggage due to fire risk. They must be carried in the cabin where crew can access them in case of thermal runaway.
It is usually printed on the battery label. For USB power banks and phones, the internal cell voltage is typically 3.7V or 3.85V, even if the USB output is 5V. Always use the nominal cell voltage (usually 3.7V) for accurate Wh calculation unless the manufacturer states otherwise.