A 30-amp RV shares one 30 A supply among its 120V appliances. An air conditioner and modest background loads may fit, while adding a microwave or electric water heater can push the total over the limit. Add the appliances’ input amps, including battery charging, then check startup demand and individual circuits separately.
Use the calculator to compare combinations before deciding what to run together. It is for a US-style 30-amp, 120V RV hookup; it does not balance the two legs of a 50-amp RV or model an inverter/charger’s power-assist system.
Calculate your RV’s running load
PLAN WHAT CAN RUN TOGETHER
30-amp RV load calculator
All starting values are illustrative examples. Replace them with your appliances’ 120V AC input amps. Select loads that could run at the same time, including thermostatically controlled appliances.
The example below uses the preset values. JavaScript enables editing; the combination table below also works without it.
Within your chosen running-load target. Startup and circuit checks still apply.
You have 6 A left before your chosen 27 A target. Do not treat this as startup capacity.
Planning estimate at nominal 120V. Adds the input amps you enter; actual combined current can differ. Does not assess starting surges, branch circuits, voltage, wiring condition or automatic load management. A positive margin is not approval to run the combination.
Read each appliance’s input label or manual, or use an installed shore-power monitor that displays amps. Enter the load while the appliance is working, not an average across its on/off cycle. A refrigerator, water heater or air conditioner can turn back on while you are cooking.
If your monitor reports the entire RV’s draw, do not enter that as “other loads” and count the same appliances again. The converter row includes the shore-power cost of supplying 12V equipment and charging the battery; do not also add those devices’ 12V amp ratings.
How much power does a 30-amp RV hookup provide?
A standard US 30-amp RV connection supplies one 120V leg, with a maximum current rating of 30 A. Jayco’s Class C manual describes this arrangement. That is a shared limit for the RV, not 30 amps available to every outlet.
You will often see this called 3,600 watts: 120 volts × 30 amps. Technically, that multiplication gives 3,600 volt-amps; it equals 3,600 watts when power factor is 1. Motors and electronic equipment can differ, so dividing every appliance’s watts by 120 can understate its current, as Vertiv’s explanation of power factor shows.
For a simple resistive heater rated 1,500 W at 120V, 1,500 ÷ 120 = 12.5 A is a useful planning example. For an air conditioner, microwave or charger, prefer documented or measured AC input amps. If you only have input watts, ask the manufacturer for the appropriate current figure rather than treating the conversion as exact.
Which appliance combinations fit?
| Appliances running together | Total | Compared with 30 A |
|---|---|---|
| Air conditioner + background loads | 21 A | 9 A below |
| Air conditioner + microwave + background | 33 A | 3 A over |
| Microwave + background; air conditioner off | 20 A | 10 A below |
| Air conditioner + electric water heat + background | 33 A | 3 A over |
| Space heater + coffee maker + background | 28.8 A | 1.2 A below |
Background = 3 A refrigerator + 4 A converter/charger + 1 A other loads. These are the calculator’s example inputs, not appliance specifications. Totals exclude starting surges and do not check individual circuits.
The table answers a running-load question only. Even the 20 A combination needs suitable circuits, connections and voltage. Your own appliance values can change the result substantially, particularly when an air conditioner is working hard or the converter is charging a depleted battery.
Can you run the air conditioner and microwave together?
Possibly, but include everything else that is running. In our example, the air conditioner uses 13 A and the microwave uses 12 A, totaling 25 A. Adding the 8 A background load takes the RV to 33 A, which is 3 A above a 30 A supply.
Cooling + background: 21 A
13 A air conditioner + 8 A background = 21 A.
9 A below the 30 A supply limit.
Add the microwave: 33 A
21 A existing load + 12 A microwave = 33 A.
3 A above the 30 A supply limit.
Both bars use the same scale. The dark vertical line marks 30 A; hatching shows unused capacity and red shows the excess. Illustrative running loads only. Starting surges and individual circuits need separate checks.
If conditions allow you to pause cooling, the microwave plus those background loads totals 20 A. Otherwise, keep cooling and postpone the microwave, or reduce another genuinely optional load. Check whether electric water heating is on before assuming there is nothing left to turn off.
Turning the air conditioner on first does not settle the problem: its compressor may stop and restart while the microwave is still running. Follow the AC manual’s restart instructions. If you are comparing units, our RV air-conditioner guide is the separate equipment-selection starting point; use your exact model’s electrical specifications for this calculation.
Three loads that are easy to count incorrectly
The converter is charging even when the lights are off
Your converter can be a substantial shore-power load after the house battery has been discharged. Its DC output rating is not the number to put into this calculator. For example, Progressive Dynamics lists the PD9260C with 60 A DC output and a separate 105–130V AC, 1,000 W input specification.
The calculator’s 4 A entry is only an example, not that model’s rating. Use your charger’s AC input information and account for its charging mode. Our RV converter guide covers the equipment; this page counts the load it places on the hookup.
Microwave cooking watts are not electrical input watts
A “1,000-watt microwave” does not necessarily draw 1,000 watts from the outlet. GE’s JVM3160RFSS specifications, for example, list 1,000 W microwave output and 1,580 W electrical input. These figures illustrate the distinction, not a recommendation to install that model in your RV.
Look for electrical input on your own unit. The cooking-power number on the front of the appliance is not enough to calculate its shore-power demand.
Water heating and refrigeration may use different energy sources
Count an electric water-heating element whenever it may energize. If your appliance supports propane operation, changing modes according to its manual may free up AC capacity; it still needs the required fuel supply and controls. Do not assume every water heater has both modes.
For a refrigerator operating on 120V, use its AC input. A 12V-only refrigerator belongs within the converter/charger’s AC demand while on shore power, rather than being entered again as a 120V appliance. Propane use has its own budget: see how long propane lasts in an RV.
Why a total below 30 amps is not the whole check
Individual outlet circuits have smaller limits
A 30 A main supply does not make every branch circuit a 30 A circuit. Suppose a 12.5 A heater and an 8.3 A coffee maker share one 15 A branch: together they draw 20.8 A, exceeding that branch rating even though the whole-RV total could be below 30 A.
Moving to a different outlet only helps if it is on a suitable separate circuit.
Check the panel’s circuit labels and your RV manual. For a portable heater, follow its placement and clearance instructions, and ESFI’s guidance to use a suitable wall outlet directly, without a power strip or extension cord. Never increase a breaker’s rating to accommodate a load.
Air-conditioner starting current is a separate demand
This calculator adds running amps; it does not predict the short surge when a compressor starts or the timing of a breaker trip. A compatible soft starter may reduce starting demand, as Micro-Air explains in its description of EasyStart. It does not increase the RV’s 30 A service rating.
Two air conditioners require both their running loads and starting behavior to be assessed, together with any factory load-management system. Do not assume a positive calculator result authorizes that combination. A generator introduces another set of output and starting limits; use our RV generator-sizing guide for that task.
A spare three amps is a planning choice
The tool begins with a 3 A margin, giving a 27 A running-load target on a 30 A supply. That buffer makes changes in background loads visible; it is not a universal electrical-code allowance, a continuous-load approval or a guarantee that the AC will start. Follow any stricter limit in your RV and appliance instructions.
Does a 50-amp pedestal give a 30-amp RV more power?
No. Even where your RV manufacturer permits a properly rated 50 A pedestal-to-30 A RV adapter, the RV remains limited to 30 A. The adapter does not upgrade its inlet, cord, wiring or main breaker. Camco describes the different adapter configurations, but the existence of an adapter is not permission to use it with every rig.
Check your RV’s instructions first: the Jayco manual linked above expressly specifies 30 A service and restricts adapters. The same caution applies to a 15 A or 20 A household connection. The calculator’s lower supply settings show reduced capacity; they do not approve a connection.
A TT-30 RV hookup is 120V, not a 240V dryer outlet.
What to check if a breaker keeps tripping
Identify whether it is the pedestal breaker, the RV main breaker or an individual branch breaker. Reduce the load on the affected circuit and follow the RV manual’s reset procedure. Repeated trips after reducing loads need a qualified technician’s diagnosis; do not keep resetting or bypass protection.
If only some receptacles are dead, our RV outlets troubleshooting guide covers that separate symptom. When assessing incoming-power protection, compare the actual features in our RV surge-protector guide: a surge rating alone does not tell you whether a device monitors voltage or disconnects for faults.
For camping without the hookup, switch to the furnace battery-runtime calculator to plan overnight heating. The rest of our RV power guides cover batteries, charging and generators.
