// LAB 13 · INTERACTIVE
mAh to Wh calculator: how many charges will a power bank give?
Turn mAh into watt-hours and see how many real phone charges a power bank gives — and if it can fly.
⚡ POWERING UP THE LAB…
// HOW IT WORKS
The idea in 30 seconds
- Wh = mAh × volts ÷ 1,000. Power banks are rated at the cell voltage, usually 3.7 V.
- About a third is lost boosting 3.7 V up to USB volts, in the cable and in the phone, so expect about two-thirds.
- A 20,000 mAh bank = 74 Wh, about 48 Wh reaches the phone: ≈ 2.5 charges of a 5,000 mAh phone.
- Airlines: up to 100 Wh in your cabin bag, 100–160 Wh only with approval, never in checked bags.
// READ THE FULL GUIDE
Step-by-step guide
Watch the lessons
More labs
All labs →LAB · INTERACTIVE · NEWMultimeter simulatorTurn the dial, plug in the probes and measure batteries, a socket, wires and LEDs — safely. Then do the job cards.LAB · INTERACTIVE · NEWElectricity bill calculatorAdd your appliances, hours and price per kWh — see what each one really costs per month.LAB · INTERACTIVE · NEWInverter backup timeEnter your battery (V, Ah) and your load in watts — see how many hours your inverter or UPS will really last.