Gas Bill Calculator
Estimate your natural gas bill from your usage in megajoules, your unit rate and daily supply charge.
Your results
Calculation breakdown
- Usage charge
- Usage charge = MJ used × rate per MJ
- Supply charge
- Supply charge = daily charge × days
Worked example
Using 6,000 MJ over a 90-day quarter at 2.7c/MJ, plus a 90c daily supply charge, gives an estimated bill of about $243.
Assumptions
- If your bill shows cubic metres, convert using your retailer's heating value factor first.
- Excludes GST if your entered rates are GST-exclusive.
- Actual bills may include additional discounts or fees.
How this calculator works
Enter your gas usage in megajoules (MJ) for the billing period, your retailer's usage rate per MJ and the daily supply charge to estimate your total gas bill. Gas usage on bills is often shown in MJ rather than cubic metres, so a conversion factor is included.
Frequently asked questions
My bill shows cubic metres, not MJ, what do I do?
Multiply cubic metres by the heating value factor on your bill (commonly around 38.5–39.3 MJ per cubic metre) to get MJ.
Does this include GST?
Toggle the GST switch on if your entered rates are GST-exclusive; most retail bills already include GST in the quoted rate.
Why does my bill vary by season?
Gas usage for heating rises sharply in winter, so seasonal usage figures give a more realistic estimate than an annual average alone.
Actual prices, usage, efficiency and savings vary by provider, equipment, location and behaviour.