RV 30 amp and 50 amp load calculator

How to use the calculator

1. Pick where you are plugged in Choose 30 amp RV, 50 amp RV, 20 amp outlet or 15 amp outlet. A 50 amp RV on a 30 amp pedestal through an adapter counts as 30 amp, because that is all the pedestal gives.
2. Tick what runs at the same time The list starts with a rooftop AC, the microwave and the fridge turned on. Tick the second AC, electric water heater, converter or heat strip if they can be on at the same moment.
3. Match the amps to your labels Each box holds a figure from a maker’s spec sheet. Type in the amps from your own unit’s data plate for a closer answer.
4. Add anything missing Tap “Add your own” for a coffee maker or space heater, and enter the amps from its label.
5. Read the verdict It reads Fits, Tight or Too much, shows the amps left over, and names a load to turn off when you are over.

How the calculator works

The math is plain addition. The calculator adds the amps of every ticked load and compares the total with what your hookup supplies at 120 volts:

• 30 amp RV: 30 A, which is 3,600 W (30 x 120).
• 50 amp RV: 100 A, because a 50 amp RV gets two separate 50 A legs at 120 V. Southwire rates its 50 amp Surge Guard at 12,000 W.
• 20 and 15 amp outlets: 20 A (2,400 W) and 15 A (1,800 W).

It then divides your total by that limit. At 80% or less it reads “Fits,” above 80% and up to 100% “Tight,” and over 100% “Too much.” When you are over, it names the smallest single load that gets you back under the limit once it is off. If no one load is big enough, it tells you to turn off the two biggest or run them one at a time.

Worked example with the starting values. The rooftop AC is 14.9 A, the microwave 12.5 A and the fridge 2.6 A. 14.9 A + 12.5 A + 2.6 A = 30.0 A, which is 100% of 30 A. The result reads “Tight” with 0 A left over. Now tick the water heater on electric at 12 A: 30.0 A + 12 A = 42.0 A, which is 12 A over. The calculator tells you to turn off the water heater, the smallest load that covers those 12 A.

Typical amp draw of RV appliances

These are the running amps behind the calculator’s list, plus two other common rooftop units.

Dometic prints compressor and fan amps separately, so we add them. The start-up surge is what trips a breaker that is already near its limit. Dometic lists the locked rotor current, the draw of a stalled or starting compressor, at 68 A for the 13,500 BTU Brisk II and 70 A for the 15,000 BTU model.

Is 30 amps enough for an RV?

For most trips, yes, if you run one big load at a time. A 30 amp RV gets 3,600 W at 120 V, and one 13,500 BTU rooftop AC takes about half of it at 14.9 A. The fridge adds 2.6 A, and the converter up to 11 A at full output. The trouble starts when heavy loads overlap. AC, microwave and electric water heater come to 14.9 + 12.5 + 12 = 39.4 A, which is 9.4 A more than the pedestal gives.

Our rule on 30 amp: one AC at a time, and the water heater on propane while you cook. If it will not light on gas, see RV water heater not working. If you have two ACs or spend summers in the heat, 30 amp will feel tight every day. Our RV electrical problems hub covers faults that look like an overload but are not.

Can you run two ACs on 30 amp?

No. Two ACs running at once do not fit on 30 amp, even with nothing else on. The 13,500 BTU Brisk II at 14.9 A plus the 15,000 BTU Brisk II at 15.3 A comes to 30.2 A. Add the fridge and you are at 32.8 A.

A soft starter does not change that. Micro-Air says its EasyStart Breeze cuts starting current by up to 75%, which helps one AC start on limited power. The running amps stay the same, and they are what put two ACs over 30 A. On a 50 amp pedestal, the same two ACs plus the microwave, fridge and water heater come to 57.3 A of the 100 A available. The calculator assumes the loads are spread across both legs, so one leg can still trip if both ACs are wired to it.

Common questions