Your energy use

Hot water calculator


There are a variety of hot water systems and tariffs available. In addition to using our calculator below to estimate the cost of hot water in your home, we recommend you ask your hot water retailer about the best system and tariff connection to suit your particular needs.

Use our calculator to estimate the cost of hot water in your home. Enter your usage details, select the types of hot water systems you would like to compare, then press “calculate”.

Hot water usage

Baths, showers and laundry

Hot water system

Use the settings below to calculate your usage for your current system. Use the ‘New system’ settings to compare your existing system with an alternate hot water system



New System

Estimated annual usage

Existing system New system
Electricity kWh/year kWh/year
Gas MJ/year MJ/year
Energy cost per year per year
Greenhouse emissions Tonnes CO2 Tonnes CO2
Annual running costs Annual greenhouse emissions
Existing System
New System
Existing System
Tonnes CO2
New System
Tonnes CO2


  1. Estimated annual running costs for electricity and natural gas are calculated using energy prices indicative of competitive 2022/23 pay-on-time offers advertised by the major energy retailers for residential customers in the Ausgrid network area and the Jemena mains gas network area.
  2. Greenhouse gas emissions are estimated using the National Greenhouse Factor of 0.79 kg/kWh for the electricity generated and distributed in NSW and 0.06463 kg/MJ for natural gas distributed to metropolitan users in NSW. These factors are published by the Department of Climate Change, Energy, the Environment and Water in the Australian National Greenhouse Accounts Factors, February 2023.
  3. Standard and low-flow showerhead flow rates assumed to be 13 litres per minute and 8 litres per minute respectively.