Power consumption calculator: watts, volts, amps & runtime
FreezAir is reader-supported. When you buy through links on our site, we may earn a commission at no extra cost to you. This never influences our scores. How we make money.
This power consumption calculator handles the three conversions cooling shoppers actually need: label volts × amps into watts, watts into daily kWh, and battery watt-hours into honest runtime for camping and van setups.
Formulas: W = V × A · kWh/day = W × h ÷ 1,000 · runtime h ≈ Wh ÷ W × 0.85 (conversion losses). Battery mAh × 3.7 V ÷ 1,000 ≈ Wh for typical packs.
The off-grid cheat sheet
Vans, tents and desks-without-sockets are where this class of device genuinely shines, because the wattage gap becomes a runtime gap. A 10 W USB cooler lives happily on power banks; a 45 W unit (like Coolizi, claimed) wants a small power station; a 340 W personal compressor needs a serious battery or mains; a 1,200 W conventional portable is a wall-socket appliance, full stop. Price the mains scenarios in the energy cost calculator.
Frequently asked questions
How do I calculate watts from volts and amps?
W = V × A — the first mode of this power consumption calculator. A label reading 230 V / 0.2 A is a 46 W device; that conversion unmasks many “mystery wattage” coolers.
How long will a power bank run my cooler?
Runtime ≈ battery Wh ÷ device W × 0.85 (inverter/USB losses). A 20,000 mAh bank (~74 Wh) runs a 10 W USB cooler roughly 6 hours — and a 45 W device only ~1.4 h.
Can a solar generator run a personal AC?
A 340 W personal compressor wants ~340 Wh per hour — realistic for mid-size power stations, heavy for small ones. Evaporative units at 5–60 W are the genuinely off-grid class.
Why does my portable AC trip the breaker?
Compressor start-up surges can double the running draw for a moment; a loaded circuit gives up. Our breaker guide walks the fixes.