RV propane usage: guide values, tanks and saving tips
In summer a 20 lb propane tank lasts for weeks, in winter sometimes only three days. The difference is called the furnace. This article provides the guide values you need to plan your propane supply realistically – and explains why a nearly empty tank suddenly fails in freezing weather.
How much energy is in a propane tank?
Propane has a heating value of about 21,600 BTU per pound (12.87 kWh/kg). A 20 lb tank therefore holds about 432,000 BTU (≈ 127 kWh) – as much as 3.4 gallons of diesel. Propane still vaporizes at −44 °F (−42 °C); butane (in some camping cartridges) fails below 32 °F (0 °C).
| Tank | Fill weight | Energy | Weight full (steel) |
|---|---|---|---|
| 1 lb cylinder | 1 lb (0.45 kg) | ≈ 21,600 BTU | ≈ 2 lb |
| 20 lb | 20 lb (9.1 kg) | ≈ 432,000 BTU (127 kWh) | ≈ 37 lb (17 kg) |
| 30 lb | 30 lb (13.6 kg) | ≈ 648,000 BTU (190 kWh) | ≈ 55 lb (25 kg) |
| 40 lb | 40 lb (18.1 kg) | ≈ 864,000 BTU (253 kWh) | ≈ 72 lb (33 kg) |
Guide values per appliance
| Appliance | Consumption | Typical per day |
|---|---|---|
| Propane furnace (Truma Combi 4 / 6) | 160–335 / 160–480 g/h (7,600–15,900 / 7,600–22,800 BTU/h) | fall 1–2 lb, winter 4–6.6 lb |
| Absorption fridge | 14–18 g/h (670–860 BTU/h) | 0.7–1 lb (330–440 g) |
| Stove (large burner) | up to 160 g/h (7,600 BTU/h) | 2–5 oz (50–150 g) |
| Water heater 2.6 gal (Truma B10) | 120 g/h (5,700 BTU/h) | ≈ 1.8 oz (50 g) per heat-up |
| Propane grill | 150–250 g/h (7,100–11,900 BTU/h) | 5–9 oz per hour |
Without the furnace, daily consumption is typically 0.7–1.1 lb (0.3–0.5 kg) – a 20 lb tank then lasts two and a half to four weeks. With the furnace the outside temperature decides: in freezing weather and a poorly insulated vehicle, 6.6 lb (3 kg) a day is not unusual.
Propane usage calculator – adds up your appliances with data sheet values
Why nearly empty tanks fail in winter
The liquid propane has to vaporize in the tank, and for that it needs heat from the surroundings. The less propane is in the tank, the smaller the liquid surface – and the less propane can vaporize per hour in the cold. A furnace drawing 300 g/h (14,000 BTU/h) no longer gets enough from a nearly empty tank at 14 °F (−10 °C). Therefore: always carry a second tank in winter and switch in good time.
Determining the fill level
- Weighing is the most accurate method: total weight minus the stamped tare weight (TW) = propane content.
- Ultrasonic level sensors work on the tank wall but are approximations.
- Condensation: after longer operation the tank is cooler below the liquid level – visible in humid air.
- Tank scales and sensors (e.g. Bluetooth) make checking easier on the road.
Saving without freezing
- Set the thermostat 4–5 °F (2–3 °C) lower at night and insulate windows/roof vents with thermal covers.
- Heat water when needed instead of keeping the heater at 140 °F (60 °C) permanently.
- Heat electrically on shore power at the campground if the electricity price is right (heating cost calculator).
- Run the fridge on 120 V at the campground.
- Cook with a lid and a matching pot size – halves the cooking time.
Heating cost calculator – compares propane, diesel and electric
Sources
- promobil: propane in the motorhome – monitoring consumption and saving energy
- Truma, Dometic, Thetford: technical data (propane consumption)
- Propane properties: heating value 46.3 MJ/kg ≙ 21,600 BTU/lb
Published 09/19/2026.