RV Power Budget Calculator

How much power does an RV use per day?

It depends on which question you're asking. Plugged into a pedestal, an RV's day is mostly air conditioning: one 13,500 BTU unit at the library's 1,500 W and 60% duty around the clock is 21,600 Wh by itself, and that shore-power meter reading is the figure most "how much electricity does an RV use" articles print. Off-grid, the answer is a different order of magnitude. A weekend couple with a propane fridge, some lights, the water pump, a few hours of TV and the furnace fan on mild nights uses about 1,425 Wh (111 Ah at 12.8 V), built from the same library as the tool above. Working from the rig with a Starlink and two laptops through the inverter costs 3.5× that, at 4,959 Wh. The dish matters: Starlink's equipment specifications put the Standard (Gen 3) kit at 75–100 W on average and the Mini at 25 W, and the older Gen 2 Standard Actuated dish averaged 50–75 W. The library plans the Standard at 88 W, the middle of its range. Whatever you build here, the number saved to My Rig is the off-grid one: hookups-only loads like the AC are flagged and left out of it.

How do you calculate RV power consumption?

Watts × hours = watt-hours, for every load, then add them up. Two details separate a useful budget from a guess. First, which circuit the load is on: a 12 V light costs the battery exactly what it draws, while a 120 V TV runs through an inverter that loses part of everything passing through it (Victron's 12 V Phoenix inverters peak at 92–93% efficiency; this page assumes 90%) and draws power of its own just for being switched on. Second, duty cycle: a fridge compressor, a furnace fan and a water heater cycle on a thermostat, so "24 hours" means 24 hours armed and perhaps 40% of that spent running. The engine applies both. Amp-hours are watt-hours divided by the bank's nominal voltage, 12.8 V for lithium and 12.0 V for lead-acid, which is why a "100 Ah" label means 1,280 Wh in one chemistry and 1,200 in the other.

Which RV appliances use the most power?

A 1,500 W hair dryer for six minutes is 150 Wh; a 12 W absorption-fridge control board for 24 hours is 288. The wattage on the label ranks loads the wrong way round, so here they are ranked by what a typical day costs, from the library the tool uses:

Delivered watt-hours at each appliance's default hours and run fraction; 120 V loads cost 11% more from the bank at 90% inverter efficiency. Hookups-only loads are listed for scale: nobody boondocks on an electric space heater.

The loads that empty a battery are the ones that run all day at modest watts: fridges, fans, routers, the furnace blower, a satellite dish. The kitchen appliances run for minutes. Trim hours on the always-on loads before you worry about the microwave.

How much power does an RV fridge use?

The fridge is the single biggest decision in the budget, and most people inherit it with the rig. Same job, four very different bills:

Library figures at moderate ambient temperature. Every fridge runs harder in a hot rig. The absorption fridge on 120 V is what happens if you leave a two-way fridge on "auto" while boondocking with an inverter; switch it to gas.

An absorption fridge on propane costs almost nothing electrically and about 0.8 lb of propane a day, 5.8 lb a week (18,000 BTU a day in the propane calculator's model). A 12 V compressor fridge is the boondocker's choice: 660 Wh a day, colder, and indifferent to whether the rig is level. A residential fridge is the price of a big motorhome's convenience: 1,440 Wh a day through the inverter in this library. Whirlpool's tech sheet for a 26 cu ft model lists 1.0 kWh a day at 70 °F and 1.3 at 90 °F with the doors shut, before anyone opens them. That is why those rigs come with big banks, and why "how many batteries do I need" starts with "what fridge do you have."

Does the RV furnace use electricity?

Yes, and it's the winter surprise. The furnace burns propane for heat, but its blower is a 12 V motor pulling about 8 A, or 100 W, the whole time the burner runs. How long that is depends on the temperature gap, computed here with the same duty-cycle rule as the propane calculator:

Furnace holding 68 °F inside. The hours come from a rule of thumb, duty cycle = (68 − outside °F) ÷ 100, which has no term for the furnace's size or the rig's insulation: at 30 °F it gives 38% for every rig. For a duty cycle worked from your rig's length and construction and your furnace's BTU, use the furnace-size calculator.

On a cold night the blower alone can use more than a compressor fridge, 912 Wh against 660, which is why lead-acid banks die on the first freezing weekend and why the season setting on this page changes the answer so much. A catalytic or blue-flame propane heater has no fan; it's the usual fix for winter boondocking, with the ventilation and CO-detector caveats that come with it.

Can you run an RV air conditioner on batteries?

Briefly, and only with a purpose-built bank. A 13,500 BTU unit draws about 1,500 W running, so eight hours at 60% duty is 7,200 Wh, as much usable energy as 7.0 lithium batteries of 100 Ah each hold at 80% depth of discharge (1,024 Wh apiece), for one day, before the inverter's losses and the surge to start the compressor. It's why the AC is flagged "hookups" in the list above and left out of the number this page saves to My Rig. The AC-on-batteries calculator checks your bank, inverter and soft start together, by duty cycle.

Where this number goes

The off-grid total saves to My Rig as your daily watt-hours. From there it becomes nights on your bank (the battery-runtime calculator runs it against your bank's chemistry and charge), the solar array that would cover it, the generator hours to refill, and the answer to "would a second battery change anything"; the battery-bank calculator turns it into how many batteries. Rebuild it when your habits change, whether that's a new fridge, a Starlink or a winter trip, and everything downstream updates with it.