Electric Heater vs Propane Cost Calculator
Compare RV overnight heating cost using electric heater watts, duty cycle, campsite kWh rate, propane furnace BTU output, furnace efficiency, propane price, outdoor load, and shore power limits.
Calculation breakdown
Current electric setup
Current propane setup
Power and capacity check
| Electric heater setting | Amps at 120 V | BTU/hr at COP 1.0 | 10 hr cost at $0.18/kWh |
|---|---|---|---|
| 500 W low personal heater | 4.2 A | 1,706 BTU/hr | $0.90 before cycling |
| 750 W half-power setting | 6.3 A | 2,559 BTU/hr | $1.35 before cycling |
| 1000 W compact heater | 8.3 A | 3,412 BTU/hr | $1.80 before cycling |
| 1500 W full space heater | 12.5 A | 5,118 BTU/hr | $2.70 before cycling |
| Propane item | BTU basis | Useful at 80% | Planning note |
|---|---|---|---|
| 1 gallon propane | 91,500 BTU | 73,200 BTU | Good for fuel cost math and tank-night estimates. |
| 20 lb cylinder | about 4.7 gal | 344,000 BTU | Real usable capacity varies by fill level and temperature. |
| 30,000 BTU/hr furnace | 30,000 BTU/hr | 24,000 BTU/hr | High output, but blower uses battery power. |
| 40,000 BTU/hr furnace | 40,000 BTU/hr | 32,000 BTU/hr | Common in larger trailers and fifth-wheels. |
| Shore power service | Nominal amps | 80% continuous target | Heater planning use |
|---|---|---|---|
| Household outlet | 15 A | 12 A | A 1500 W heater alone may exceed the continuous target. |
| Garage or 20A pedestal | 20 A | 16 A | Often supports a space heater plus small background loads. |
| 30A RV pedestal | 30 A | 24 A | Watch water heater, microwave, converter, and heated hose loads. |
| 50A RV service leg | 50 A | 40 A per leg | More headroom, but appliance balancing still matters. |
| Outdoor condition | Load factor | Typical duty change | RV detail to check |
|---|---|---|---|
| Sheltered mild site | 70% to 85% | Shorter cycles | Tree cover, low wind, few exposed slide seals. |
| Typical cold campsite | 100% | Normal cycles | Use this as the baseline for comparison. |
| Windy with slides out | 118% | Longer cycles | Slide floors, door seals, vent covers, and underbelly exposure. |
| Hard freeze or poor sealing | 135% | Near-continuous cycles | Basement heat, water bay protection, and skirted airflow. |
electric kWh = watts / 1000 x overnight hours x electric duty cycle; useful electric BTU = kWh x 3412 x COP.propane gallons = furnace BTU/hr x overnight hours x furnace duty cycle / 91500; useful propane BTU = input BTU x furnace efficiency.load-adjusted comparison = useful heat x temperature span ratio x selected outdoor load factor, with shore amps checked against 80% of pedestal rating.
At 2:00 AM, the RV’s thermostat clicks. As indoor temperature cools down to match outdoor temperature, panic sets in. Do I turn on electric space heater? Will pedestal stand up to it? Or do I go with propane furnace and hope my fuel tank lasts long enough to avoid frozen pipes?
It’s a crapshoot; a coin toss. Flip the electric switch and hope you don’t blow a breaker, kick on the propane and run the fuel meter down to bottom. In this situation, your budget meets physics and comfort all at once.
Choosing Between Electric and Propane Heat
Many people guess, and unfortunatly they are wrong about half the time. This lead them back to campground office to reset blown breakers, or to supply station to top off their tanks. With a calculator, though, someone else is running numbers, but the true benefit is knowing what they mean in terms of available power and how much energy is being transfered.
The simplicity of electric heat can be deceiving. Plug in 1,500-watt heater and it draw 12.5 amps continuously. Each kilowatt-hour produce approximately 3,412 BTUs of heat. It’s a one-to-one conversion; there are no losses between input and output.
Here’s the catch: Once you’re plugged into a limited circuit, electricity is a finite resource. For example, a typical 30-amp RV pedestal will support around 24 amps safely continuously. Maybe you’ve got lights on, you’re charging house batteries, and you’ve got an electric water heater. That electric space heater may very well be the last load that trips breaker. Be sure to factor in those background loads that folks tend to forget about until the lights goes out.
Using propane is a different story. It involves mechanics and chemistry. You have roughly 91,500 BTUs of energy potential in each gallon, but your furnace isn’t going to be perfect. If you’ve got an older one you may get as little as 70% of its potential output into actual heat, whereas moddern sealed systems can approach 85% efficiency. In addition to this, there’s battery power needed for the blower fan, which means you want a strong charging plan if you’re counting solely on propane.
Propane will give you huge surges of heat with far less reliance based off your shore power supply; but you’ll burn through your fuel tank at a quicker pace then expected. The catch is obvious: using propane gives you lots of heat, but it also runs out faster than you expect. But it usually ends up being about the duty cycle (the percent of the time the heater is on vs off).
With good insulation and a mild night, you may need to only have electric heater running 50% of the time. This keep the amp draw reasonable and keeps costs down. But in a hard freeze with wind whipping around your slides, that duty cycle will spike, causing the electric load to become unsustainable and propane usage to become too expensive. This change is reflected in the load factor inputs (which account for exposure of your site). Big difference between a sheltered location behind a tree vs out in middle of an open field.
So many people focus on the price per kilowatt-hour (or per gallon) but fail to consider how much capacity the system can provide. A typical 20-pound propane cylinder contain about 4.7 gallons. So if it’s a cold night when heat demand is high, you may go through quite a bit of that tank in just one evening. Similarly, an electric meter at a resort may have a higher per-unit cost so your numbers appear worse when they aren’t. You’re paying for convenience. The ability to keep running all night without intervening, but you also should of consider the out-of-pocket expense immediately.
So which is right? There’s no one right answer to that question, it all depends upon the conditions. Mild weather? Electric is tough to beat if you’ve got a good hookup. Freezing temps or boondocking? Propane is your friend, it will keep the chill away in an instant. A lot of times, a hybrid system can be the best bet depending on weather conditions. You can run on electric on milder nights to conserve fuel, then flip over to propane when temps dip below your electrical comfort zone. Knowing the dynamics behind this help take the guess work out of the equation and allows you to get some solid rest knowing exactly how much energy you are burning.
