Updated September 2026
12V Power
Inverter size calculator for sleeper cab
Tick everything you run in the bunk. We total the watts, add 25% headroom, and name the inverter size — no guesswork, no popped fuses. Still shopping? Compare the winners in our best portable power station for truck drivers ranking.
What do you run in the bunk?
Tick every device you run at the same time. Wattages are typical published figures — check your device labels.
Tick at least one device above to size your inverter.
Above 12V socket limits. Most accessory sockets are fused at 10–15 A (about 120–180 W). This load needs direct battery wiring with proper-gauge cable and an inline fuse.
Surge matters too. Motors, compressors and heating elements spike well above running watts on startup — pick an inverter whose surge rating is at least double your total.
That is beyond a typical single-inverter sleeper setup. Stagger big loads (never the kettle and the microwave together) or split across two inverters.
- Size for continuous watts, not peak — the big number on the box is the continuous rating; surge is separate and short.
- Pure sine wave for a CPAP machine, laptop or microwave — their manufacturers specify it.
- Add up what runs at the same time. Stagger the kettle and the microwave and you can drop a size class.
- The 25% headroom covers inverter inefficiency (typically 10–15% is lost as heat) plus small startup spikes.
total W × 1.25 → next standard size
This sizes the inverter — not whether the truck can feed it. Battery bank, alternator, cable gauge and fuses all have to support the load independently.
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Research-based. We did not test these hands-on. Scores come from published specs and driver reviews. Wattages are typical published figures — your device label is the source of truth, and every input here is adjustable. Change anything and the math re-runs.