Skip to content
CampingCalc

Propane Usage Calculator: How much propane do furnace, stove and fridge use?

The furnace is by far the biggest consumer: a Truma Combi 4 uses 335 g (0.74 lb) per hour at full output – if the burner runs a third of the night in fall, that's over 2 lb a day. Stove, water heater and absorption fridge add to it. This calculator adds up all propane appliances with their data sheet values and shows how long 20 and 30 lb tanks last.

Units

Propane appliances

Consumption per the data sheet (at full output), operating hours and duty cycle (thermostat: share in which the burner actually runs).

Result

Propane consumption per day

3.72 lb

60 oz per day

Per week
26.1 lb
20-lb tank lasts
5.4 days
30-lb tank lasts
8.1 days
Energy per day
21.7 kWh
  • “Furnace Truma Combi 4 – fall” causes 71% of the consumption. For furnaces the duty cycle decides – in winter it's easily 50–70%.
Show calculation
  1. 1Furnace Truma Combi 4 – fall: 15,946 BTU/h × 12 h × 30% = 43 oz/day
  2. 2Absorption fridge: 714 BTU/h × 24 h × 100% = 13 oz/day
  3. 3Stove large burner: 7,140 BTU/h × 0.5 h × 100% = 3 oz/day
  4. 4Water heater heat-up: 5,712 BTU/h × 0.4 h × 100% = 2 oz/day
  5. 5Total: 60 oz/day = 3.72 lb/day (≙ 21.7 kWh of energy)
  6. 620-lb tank: 20 lb ÷ 3.72 lb/day = 5.4 days

 

How it's calculated

Consumption per appliance [g/day] = consumption [g/h] × operating hours × duty cycle
Furnace: 335 g/h × 12 h × 30% = 1,206 g (2.7 lb)

The duty cycle is decisive for thermostat-controlled appliances: the furnace may be “on” for 12 hours, but the burner only runs part of that – 20–40% in fall, 50–70% in freezing weather. Stove, water heater and grill run continuously while in use (100%).

If you know the heat output instead of the propane consumption: g/h = kW ÷ (12.87 kWh/kg × efficiency) × 1,000, or in US units lb/h = BTU/h ÷ (21,600 BTU/lb × efficiency). A 4 kW (13,650 BTU/h) furnace at 93% efficiency thus comes to 334 g/h (0.74 lb/h) – exactly the data sheet value of the Truma Combi 4.

Typical consumption figures (manufacturer data, rounded)
ApplianceConsumption at full output
Truma Combi 4 / 4 E160–335 g/h (7,600–15,900 BTU/h)
Truma Combi 6 / 6 E160–480 g/h (7,600–22,800 BTU/h)
Trumatic S 300430–280 g/h (1,400–13,300 BTU/h)
Absorption fridge 3–3.5 cu ft14–18 g/h (670–860 BTU/h)
Stove small / large burnerabout 70 / up to 160 g/h (3,300 / 7,600 BTU/h)
Water heater Truma B10120 g/h (5,700 BTU/h)

Worked example

Winter camping at 23 °F (−5 °C): Combi 6 runs around the clock at 50% duty cycle, absorption fridge on propane, 45 minutes of cooking, two water heater heat-ups.

Inputs

  • Propane appliances:
  • Heizung Truma Combi 6 – Winter: 22,848 BTU/h × 24 h/day × 50 %
  • Absorberkühlschrank: 714 BTU/h × 24 h/day × 100 %
  • Kocher großer Brenner: 7,140 BTU/h × 0.75 h/day × 100 %
  • Boiler-Aufheizung: 5,712 BTU/h × 0.8 h/day × 100 %

Result

13.95 lb

Propane consumption per day

Per week
97.7 lb
20-lb tank lasts
1.4 days
30-lb tank lasts
2.1 days
Energy per day
81.4 kWh

Calculation

  1. Heizung Truma Combi 6 – Winter: 22,848 BTU/h × 24 h × 50% = 203 oz/day
  2. Absorberkühlschrank: 714 BTU/h × 24 h × 100% = 13 oz/day
  3. Kocher großer Brenner: 7,140 BTU/h × 0.8 h × 100% = 4 oz/day
  4. Boiler-Aufheizung: 5,712 BTU/h × 0.8 h × 100% = 3 oz/day
  5. Total: 223 oz/day = 13.95 lb/day (≙ 81.4 kWh of energy)
  6. 20-lb tank: 20 lb ÷ 13.95 lb/day = 1.4 days

The variables explained

Consumption (g/h or BTU/h)
Maximum propane consumption per the data sheet at full output. 1 lb/h ≈ 21,600 BTU/h ≈ 454 g/h.
Operation (h/day)
Hours the appliance is switched on.
Duty cycle (%)
Share of the operating time in which the burner actually runs at full output (thermostat, output level).

Common mistakes

  • Calculating the furnace at 100% duty cycle – that usually overestimates consumption twofold.
  • Modulating furnaces (Combi) often run on the low setting – then 160 g/h × a higher duty cycle is more realistic.
  • Counting the fridge on propane even though it runs on 12 V on the road or on 120 V at the campground.
  • Forgetting freezing weather: below 32 °F nearly empty propane vaporizes too slowly for the furnace.

Assumptions and limits

  • Heating value of propane 12.87 kWh/kg (21,600 BTU/lb).
  • Data sheet values in the presets are typical; your own data sheet takes precedence.
  • Duty cycles are estimates and depend strongly on temperature, insulation and desired temperature.

Sources and background