Laptop Battery Wh, Calculated: Why 100Wh Is the Carry-On Limit
Divide mAh by 1,000 and multiply by voltage to get watt-hours. Laptops quote Wh instead of mAh because cells wired in series give every model a different voltage — and 100Wh and 160Wh are the lines that decide how many batteries you can carry onto a plane.
