RV Propane Usage & Run-Time Calculation
Calculating approximate propane usage is essential when planning several days of off-grid dry camping or boondocking. Remember that an RV propane tank or cylinder is considered 100% full at 80% liquid volume capacity to allow proper expansion room for liquid LP expansion.
How to Calculate Total Appliance Run-Time
Multiply your total filled propane volume in US gallons by 91,502 BTUs to determine total available energy capacity. Then, sum the maximum BTU ratings of the appliances you plan to run (found on appliance dataplate labels or owner's manuals) and divide the total container BTUs by total appliance BTU demand.
Sample Calculation:
If your RV LP container holds 14 US gallons when filled to 80% capacity:
$$14 \text{ gallons} \times 91,502 \text{ BTUs/gallon} = 1,281,028 \text{ Total BTUs}$$
If running a furnace, water heater, and absorption fridge drawing a combined 43,800 BTUs/hour:
$$\frac{1,281,028 \text{ BTUs}}{43,800 \text{ BTUs/hour}} \approx 29.2 \text{ hours of continuous duty}$$
Cold Weather Warning: At ambient freezing temperatures below 0°F (-18°C), LP gas vaporization rates drop drastically, effectively reducing usable tank BTU output by 50% or more.
Tip contributed by Mark Polk at RV Education 101.