Gas Appliance Running Cost Calculator
What a gas appliance costs to run from its rated input, the hours it runs and your gas price — per hour, per day and per year — with the emissions.
Gas appliances are rated by energy input, in megajoules per hour or kilowatts (1 kW = 3.
How the gas appliance running cost calculator works
Gas appliances are rated by energy input, in megajoules per hour or kilowatts (1 kW = 3.6 MJ/h). Multiply the rating by the hours of use for energy, then by the price per megajoule on your bill. Natural gas releases about 51.5 g of CO₂ per megajoule burned. Appliances cycle on and off, so use the hours the burner is actually on — a thermostat-controlled heater might burn half the time it is switched on.
Formula: MJ = rating (MJ/h) × hours; cost = MJ × price per MJ; CO₂ = MJ × 0.0515 kg
Worked examples
| Inputs | Cost per year | Note |
|---|---|---|
| 25 MJ/h heater, 4 h a day for 120 days at 0.04 | 480 | 480 a year |
| 10 kW cooktop, 1 h a day all year | 262.8 | 263 a year |
| 40,000 BTU/h furnace, 6 h a day for 150 days | 531.75 | 532 a year |
FAQFrequently asked questions
Where do I find the rating?
On the compliance plate or in the manual — “input 25 MJ/h”, “20 kW input”, or “65,000 BTU/h”. Use the input, not the heat output, because you pay for the gas going in.
How do I get the price per MJ?
From the usage charge on your gas bill. Bills in kWh (UK, parts of Europe) divide by 3.6 for the price per MJ; bills in therms divide by 105.5; bills in cubic metres or cubic feet need the heating value printed on the bill.
Does the appliance burn the whole time it is on?
Heaters and hot-water systems cycle with a thermostat — often 40–60% of the time. Cooktops burn continuously while lit. Enter the hours the flame is actually on for a fair estimate.
Is gas cheaper than electricity for this?
Per unit of energy gas is usually cheaper, but a heat pump delivers three or more units of heat per unit of electricity, which often makes reverse-cycle heating and heat-pump hot water cheaper to run than gas. Compare the delivered heat, not the fuel.
Where these figures come from
- International Energy Agency — Energy Efficiency — appliance consumption and standby power context
- Australian Energy Regulator — the Australian energy market regulator
Last checked: September 2026. Appliance power figures are typical ratings; check the label on your own equipment, which is authoritative for it.