Hot Water Cost Calculator
Estimate gas hot water running costs from household size, daily water use, temperature rise, and system efficiency.
Key takeaways
- Hot water cost is driven by usage volume, incoming water temperature, and system efficiency.
- This is useful when comparing households, shower habits, or appliance upgrades.
- Annual estimates help show whether high-usage families should prioritise hot water efficiency first.
Household hot water use
System assumptions
Hot water cost snapshot
$0.69
estimated daily hot water cost
Monthly cost
$20.60
Annual cost
$250.67
Gas needed
19.6 MJ/day
What does this hot water estimate mean?
The calculator converts hot water demand into useful energy, then adjusts for gas system efficiency to estimate how much gas your household needs each day.
If your family takes long showers or uses large volumes of hot water, increase the daily litres-per-person assumption rather than changing the gas tariff alone.
What should you compare next?
FAQ
Hot water calculator questions
What does litres per person per day mean?
It is the amount of hot water each person uses across showers, hand washing, dishwashing, and other daily tasks.
Why is temperature rise important?
Heating colder inlet water takes more energy. A larger temperature difference means a higher hot water cost.
What if I have a very efficient system?
Increase the efficiency setting closer to the real appliance rating. A more efficient system reduces gas needed for the same useful hot water output.