What Size Inverter for a Camper Van or RV?
Size a pure-sine inverter to the largest set of AC appliances you will ever
run at the same time, not the sum of everything you own. Take that peak
simultaneous load, multiply by 1.25 for headroom, and pick the next standard
inverter: continuous watts = simultaneous watts × 1.25. Then check
surge: motors and compressors can draw 2–3× their running watts for a fraction
of a second at startup, so the inverter's surge rating must cover that spike.
Worked example
Running a 900 W microwave, a 60 W laptop, and 40 W of lights together is
1,000 W. 1,000 × 1.25 = 1,250 W, so a 1,500 W
inverter (with ~3,000 W surge) is the right call. If the most you ever run is a
few small DC-adjacent chargers totalling under 100 W, a 300 W inverter is
plenty.
| Peak simultaneous load | Continuous need | Inverter |
|---|---|---|
| LED lights + laptop + charger (~95 W) | 119 W | 300 W |
| Blender or coffee maker (~800 W) | 1,000 W | 1,000 W |
| Microwave + laptop + lights (~1,000 W) | 1,250 W | 1,500 W |
| Induction cooktop (~1,800 W) | 2,250 W | 3,000 W |
| Air fryer + fridge + laptop (~2,100 W) | 2,625 W | 3,000 W |
A bigger inverter is not automatically better: larger units draw more idle power and demand thicker, more expensive battery cable and a larger fuse. Size it to your real loads, and remember every AC watt still comes from the battery — a big inverter does not mean a big battery unless you build one.
Quick start with a profile:
Your daily loads
Add each device with its watts and hours per day.
No loads yet. Add your fridge to start, or pick a profile above.
Solar array
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Battery bank
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Charge controller (MPPT)
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Inverter
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Battery-to-inverter wire & fuse
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Estimated cost
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Budget street price → premium brands.