Free RV Electrical Calculator — Shore Power, Off-Grid & System Sizing

Check shore power capacity, estimate battery runtime off-grid, and size your solar and inverter setup. Covers 30A/50A hookups, lithium and lead-acid banks, and solar harvest — no sign-up required.

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What This Calculator Checks

Shore power load check for 30A and 50A hookups
Battery runtime estimate for off-grid camping
Solar harvest calculation based on panel wattage and sun hours
Inverter sizing for AC appliances off battery
Load prioritization when shore power is limited
Battery bank sizing for lithium and lead-acid
Downloadable power budget report

RV Electrical Calculator

Choose a scenario below and enter your appliances to see whether your electrical setup can handle the load.

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No account needed No tracking 3 calculation flows Downloadable report

How It Works

1

Pick Your Scenario

Choose shore power check, off-grid power budget, or full system builder. Each flow asks only the questions that matter.

2

Enter Your Loads

Add appliances, lights, and devices with their wattage and daily run time. The calculator tallies amps, watts, and watt-hours in real time.

3

See Your Results

Get a clear verdict — will your setup handle the load? See exactly how much headroom you have or what needs to change.

What Is Shore Power and Why Does It Matter?

Shore power is the electrical hookup at a campground pedestal that feeds your RV's AC system. Most sites offer either a 30-amp or 50-amp connection. Knowing your shore power capacity — and how much your appliances draw — prevents tripped breakers, damaged equipment, and frustrating campsite blackouts.

  • Capacity — A 30A hookup delivers about 3,600 watts; a 50A hookup delivers about 12,000 watts
  • Breaker trips — Running too many appliances at once overloads the circuit and kills power to your rig
  • Equipment damage — Sustained low voltage (brownouts) can harm your air conditioner compressor and electronics
  • Planning — Knowing your load lets you decide what to run simultaneously and what to stagger

RV Electrical Terms Explained

Abbreviation Full Name Definition
W Watt Unit of electrical power. Volts multiplied by amps. Tells you how much power a device uses at a given moment.
A Amp (Ampere) Unit of electrical current — how much electricity is flowing. Your shore power breaker is rated in amps (30A or 50A).
V Volt Unit of electrical pressure. RV systems use 120V AC (shore/inverter) and 12V DC (battery/house system).
Ah Amp-Hour Battery capacity measure — one amp drawn for one hour. A 100Ah battery can deliver 1A for 100 hours or 10A for 10 hours (ideally).
Wh Watt-Hour Energy consumed over time. A 100W appliance running for 3 hours uses 300Wh. Used to calculate daily energy budgets.
DoD Depth of Discharge How much of a battery's capacity you actually use. Lead-acid should stay above 50%; lithium can safely go to 80-90%.
SOC State of Charge The inverse of DoD — how full the battery is. 100% SOC means fully charged, 0% means completely discharged.
kWh Kilowatt-Hour One thousand watt-hours. Utility power is billed in kWh. A 400Ah 12V lithium bank stores about 4.8 kWh of usable energy.

Common RV Electrical Mistakes

Running AC on a 30A hookup with other loads

A rooftop air conditioner draws 12-16 amps alone. On a 30A connection, that leaves little room for a water heater, microwave, or hair dryer running at the same time.

Draining lead-acid below 50%

Lead-acid batteries lose cycle life rapidly when discharged past 50%. Treating them like lithium (80-90% DoD) can cut their lifespan from years to months.

Overestimating solar harvest

Panel ratings are measured in lab conditions. Real-world output depends on angle, shade, temperature, and hours of direct sun — expect 60-75% of the rated wattage.

Ignoring phantom loads

Appliances on standby, always-on inverters, and control boards draw small but constant power. Over 24 hours, phantom loads of 3-5 amps can drain 70-120Ah from your batteries.

Mixing up 30A and 50A connections

A 30A plug uses 3 prongs (one 120V leg); a 50A plug uses 4 prongs (two 120V legs). Using a dogbone adapter without understanding the capacity difference can overload your system.

Frequently Asked Questions

What is shore power?
Shore power is the AC electricity supplied by a campground pedestal to your RV. It's called "shore" power because the term comes from boats plugging into dock-side outlets. Most RV parks offer 30-amp or 50-amp hookups.
What is the difference between 30A and 50A hookups?
A 30-amp hookup provides one 120V hot leg at 30 amps — about 3,600 watts total. A 50-amp hookup provides two 120V hot legs at 50 amps each — about 12,000 watts total. The 50-amp service is not just "a little more" — it's over three times the capacity.
How long will my batteries last off-grid?
It depends on your battery capacity, depth of discharge, and daily energy consumption. A 200Ah lithium bank at 80% DoD gives you 160Ah of usable capacity. If your loads draw 40Ah/day, you get about 4 days — less if you're not recharging with solar.
How much solar do I need for my RV?
Start by calculating your daily watt-hour consumption. Divide that by the average peak sun hours for your region (typically 4-6 hours in the US) and derate by 25% for real-world losses. For example, 1,500Wh/day ÷ 5 sun hours ÷ 0.75 ≈ 400W of panel capacity.
What size inverter do I need?
Size your inverter to handle the largest simultaneous AC load you'll run on battery power. A microwave (1,000-1,200W) plus a few lights and a phone charger might peak at 1,500W. Add a 20% buffer — so a 2,000W inverter would be appropriate.
What is depth of discharge (DoD)?
Depth of discharge is the percentage of a battery's total capacity that has been used. A 200Ah battery at 50% DoD has delivered 100Ah. Lead-acid batteries should not exceed 50% DoD regularly; lithium (LiFePO4) batteries can safely go to 80-90% DoD.
Do I need a battery monitor?
Yes, if you boondock or rely on batteries. Voltage alone is an unreliable indicator of remaining capacity. A shunt-based battery monitor (like a Victron SmartShunt) tracks actual amp-hours in and out, giving you an accurate state of charge reading.
Can I run my air conditioner on battery power?
Yes, but it requires a significant investment. A standard rooftop AC draws about 1,200-1,500W running (2,500-3,000W starting). You'll need at least a 3,000W inverter and a battery bank large enough to sustain the load — typically 400Ah+ of lithium for a few hours of runtime.
What are phantom loads?
Phantom loads are small, continuous power draws from devices on standby — things like an always-on inverter, CO detector, propane detector, stereo head unit, and slide-out control board. Individually small (0.5-2A each), they add up to 3-5 amps and can drain 70-120Ah over 24 hours.
How do I calculate my RV's daily power consumption?
List every electrical device you use, note its wattage, and estimate daily run time in hours. Multiply watts × hours to get watt-hours per device. Sum all devices for your daily total. The AmpSmart calculator automates this — just pick your appliances and set run times.

RV Electrical Resources

Dig deeper into RV electrical systems with these guides.

RV Shore Power Explained: 30A vs 50A

Everything you need to know about campground electrical hookups.

RV Solar Sizing Guide

How to calculate the right amount of solar for your camping style.

RV Battery Types Compared

Lead-acid vs AGM vs lithium — pros, cons, and when each makes sense.

RV Inverter Sizing Guide

How to pick the right inverter for your AC loads and battery bank.

Boondocking Power Management Tips

Practical strategies for stretching your battery life off-grid.

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