Home Energy Cost Calculator
The whole energy bill of a home: what it is today, what it costs per square metre and where the money goes.
Energy is the running cost of a home that you can still change after you have bought or rented it. Knowing which part of the bill is largest, and what it costs per square metre, is what turns a vague intention to insulate into a decision.
Enter the year of consumption and prices for electricity, heating, hot water and any other fuel, and this calculator gives the annual and monthly cost, the cost per square metre, the breakdown and what a saving in each part would be worth.
At a glance
- What you enter
- Electricity used per year, Price per kWh of electricity, Heating energy used per year, Price per kWh of heating energy, Hot water energy used per year, Price per kWh for hot water, Other energy costs per year, Floor area, Saving to test
- What you get
- Energy cost per year, Energy cost per month, Cost per square metre, Saving from the target reduction, Monthly saving from the target reduction, Energy per square metre
- Formula shown
- Yes - every step, right below your results.
- Cost and privacy
- Free, no account needed, and nothing you type is stored.
See worked examples ↓ Read the FAQ ↓ Share this calculator ↓
Results are estimates for general information only - always verify with a professional or official source before acting on them.
How to use the Home Energy Cost Calculator
- 1 Enter Electricity used per year (kWh)
- 2 Enter Price per kWh of electricity
- 3 Enter Heating energy used per year (kWh)
- 4 Enter Price per kWh of heating energy
- 5 Enter Hot water energy used per year (kWh)
- 6 Enter Price per kWh for hot water
- 7 Enter Other energy costs per year - Standing charges, solid fuel, bottled gas, generator fuel.
- 8 Enter Floor area (square metres)
- 9 Enter Saving to test
- 10 Press Calculate. You get Energy cost per year, Energy cost per month, Cost per square metre, Saving from the target reduction, Monthly saving from the target reduction, Energy per square metre, and every intermediate step stays visible under “How is this calculated?”
- 11 Change one number at a time to see what moves the result - that is usually the most useful thing a calculator can tell you.
Worked examples
Real numbers run through this calculator. Open any example to load it into the form above and change it.
A 120 square metre home using 18,000 kWh of energy
Gas heating and hot water with electricity at 26 cents and gas at 10 cents per kWh.
You enter
- Electricity used per year
- 3,500 kWh
- Price per kWh of electricity
- $0.26
- Heating energy used per year
- 12,000 kWh
- Price per kWh of heating energy
- $0.10
- Hot water energy used per year
- 2,500 kWh
- Price per kWh for hot water
- $0.10
- Other energy costs per year
- $180.00
- Floor area
- 120 square metres
- Saving to test
- 15%
You get
- Energy cost per year
- $2,540.00
- Energy cost per month
- $211.67
- Cost per square metre
- $21.17
- Saving from the target reduction
- $381.00
- Monthly saving from the target reduction
- $31.75
- Energy per square metre
- 150.00 kWh
Electricity costs $910.00, heating $1,200.00, hot water $250.00 and other fuels $180.00, so the year comes to $2,540.00, or $211.67 a month, which is $21.17 per square metre. Total use is 18,000 kWh, or 150 kWh per square metre. Heating is 47.2% of the bill, electricity 35.8%, hot water 9.8% and other fuels 7.1%. Cutting the whole bill by 15% would save $381.00 a year, or $31.75 a month.
A 70 square metre flat using 10,800 kWh of energy
A smaller home with a higher electricity price and cheaper heating energy, testing a 20% cut.
You enter
- Electricity used per year
- 2,000 kWh
- Price per kWh of electricity
- $0.28
- Heating energy used per year
- 7,000 kWh
- Price per kWh of heating energy
- $0.09
- Hot water energy used per year
- 1,800 kWh
- Price per kWh for hot water
- $0.09
- Other energy costs per year
- $90.00
- Floor area
- 70 square metres
- Saving to test
- 20%
You get
- Energy cost per year
- $1,442.00
- Energy cost per month
- $120.17
- Cost per square metre
- $20.60
- Saving from the target reduction
- $288.40
- Monthly saving from the target reduction
- $24.03
- Energy per square metre
- 154.29 kWh
Electricity costs $560.00, heating $630.00, hot water $162.00 and other fuels $90.00, so the year comes to $1,442.00, or $120.17 a month, which is $20.60 per square metre. Total use is 10,800 kWh, or 154.3 kWh per square metre, more per square metre than the larger home even though the bill is far smaller. Heating is 43.7% of it and electricity 38.8%, and a 20% cut would save $288.40 a year, or $24.03 a month.
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Frequently asked questions
How do I find my kWh figures?
From your bills. Electricity is metered in kilowatt hours directly. Gas is usually metered in cubic metres or hundreds of cubic feet and the bill converts it using a calorific value, so use the kWh figure printed on the bill rather than the meter reading. Oil and bottled gas are measured in litres or kilograms and need converting.
Use a full year rather than a winter month, and if you have moved recently, ask the supplier for the annual consumption of the property or use the previous occupant's figures. A year of real data beats any estimate built from floor area.
What does the cost per square metre tell me?
It makes two homes comparable when they are different sizes. A large house always has a bigger bill, so the total tells you little on its own; the cost per square metre shows how much energy each square metre needs, which reflects insulation, heating system and habits.
The comparison is only fair if both figures are built the same way: same period, same fuels, and standing charges either included in both or excluded from both. It says nothing about comfort either, so a low figure can mean a well-insulated home or a cold one.
Should heating and hot water use the same price?
Only if they use the same fuel. A gas boiler heating the house and an electric immersion heater for hot water have very different prices per kilowatt hour, and the separate fields exist so each can be entered correctly. If both come from the same gas boiler, use the same figure in both.
If the bill combines them and you cannot separate the two, put the whole amount in the heating line and set hot water to zero rather than splitting it at a guess, because a guess on both sides makes every share on the page misleading.
Where should I cut first?
Start with the largest share, which in a cold climate is usually heating. Insulation and draught proofing reduce the demand itself, while a lower thermostat reduces how much of it you ask for, and both show up in the cost per square metre. The Heating Cost Calculator tests insulation and thermostat changes in more detail.
After that, look at the appliances that run longest rather than those with the highest rating, which is what the Electricity Cost Calculator is for. The saving target is applied to the whole bill, so treat it as a goal rather than an assumption that every part can be cut by the same amount.
Terms used here
Short, plain-language definitions of the words this calculator uses.