Skip to main content Skip to main navigation
Skip to access and inclusion page Skip to search input

What is a carbon footprint, and how to understand it

Understanding and measuring your carbon footprint is a helpful step towards making a positive change when it comes to your individual impact on the environment. What exactly is a carbon footprint, and how can you take steps to manage yours?



1.  What is a carbon footprint?

A carbon footprint measures the amount of greenhouse gases (including CO2, methane and other greenhouse gases) released into the atmosphere due to day-to-day human activities. It represents impacts on climate change from the indirect and direct emissions generated by daily activity and decisions on the goods and services we consume and use.

Knowing this impact can be a significant step to assist in making decisions to live more sustainably.


Carbon footprints are typically measured in units of carbon dioxide equivalents (CO2e).


Carbon footprints take into account the global warming potential of greenhouse gases, including CO2 and methane, and their relative contributions. For example, one ton of methane emissions equals about 29.8 tons of CO2e because methane has a stronger global warming potential than CO2.

Why’s it important to understand your estimated carbon footprint?

The carbon footprint concept is all about providing information that can potentially help identify the activities in your life that may contribute to your overall carbon emissions.


Understanding the estimated carbon footprint of your transactions may help you consider ways that could reduce your personal carbon emissions.

Is it the same thing as an ecological footprint?

No, a carbon footprint relates to the impact created on the climate as we go about our daily lives. In contrast, an ecological footprint is an environmental impact, expressed as the amount of land required to sustain the use of natural resources.


Westpac's Carbon Footprint Tracker

Built into the Westpac App, our Carbon Footprint Tracker could help you better understand the estimated amount of carbon emissions associated with transactions made from your eligible Westpac accounts. Knowing this can be a helpful step towards understanding how to live more sustainably.


2.   How's an average carbon footprint calculated?


Individual and collective actions all count towards your average carbon footprint. While there are different methodologies to calculate it, it's important to remember that although it's a science, it's not perfect.

How does the Westpac App calculate estimated carbon footprints?

The Westpac App uses two pieces of data to calculate an estimated monthly carbon footprint:

  • The transaction amount
  • The transaction’s industry category, which has an associated emissions factor based on Australian industry average data.


The Tracker analyses eligible transactions from included Westpac accounts and allocates a specific industry type to these transactions depending on the merchant type (for example, fashion, groceries, or insurance).


The Westpac Carbon Footprint Tracker uses a spend-based calculator, which is one of many types of calculators that may be used to estimate carbon footprints.


Each eligible transaction is multiplied by an 'emissions factor' (how much carbon dioxide equivalents (CO2e) that type of activity emits per dollar spent) to work out the estimated carbon footprint for that transaction. For example, every time you use a Westpac card (linked to an eligible Westpac account) at a petrol station or supermarket, you’ll see the estimated emissions associated with that purchase. These individual transactions are then combined into a monthly view of an individual's estimated carbon footprint.

How accurate are the results?

Since we can’t see the specific items you purchase or any of your lifestyle choices, such as your diet (e.g., if you’re vegetarian) or energy consumption choices (e.g., if you’ve selected ‘green energy’ from your provider), we apply an average Australian emissions factor to your purchases to give you an estimated carbon footprint associated with that transaction.


All carbon footprint CO2e (carbon dioxide equivalent) values are estimates based on research by our partner, Cogo, at an industry and country level.


While we do our best to link eligible transactions to the correct categories in the Carbon Footprint Tracker, sometimes we may get it wrong or are unable to categorise certain transactions. For example, you may have gone to the petrol station and purchased lunch rather than fuel, or a transaction on your transaction listing displays as ‘Uncategorised’. You know your spending activities best, so we recommend reviewing your transactions regularly. Re-categorising them or assigning an ‘Uncategorised’ transaction to a specific category may help give you a more accurate estimate of your carbon footprint.


Who is Cogo?

Cogo are carbon footprint management experts who help individuals and businesses measure, understand and look at ways to potentially reduce their carbon footprint. Using best-in-class models available today, they measure carbon emissions specific to local markets, helping customers make more sustainable choices. Through our partnership with Cogo, we’ve integrated their expertise into the Westpac Carbon Footprint Tracker.


3.  Where do greenhouse gas emissions come from?

Emissions come from a wide variety of sources, including electricity generation, transportation, forestry, manufacturing, and agriculture, to name a few. Certain industries and companies are more sustainable than others and have lower carbon emissions. For example, in Australia, higher emitting industries today include energy (gas, electricity and petrol), flights, and other modes of transport relying on fossil fuels.


As an individual, your carbon emissions come from various sources and activities in your everyday life.


Having the information to start to understand the impact of different activities could help you identify how you could make changes to or be more conscious of your activities in certain areas and reduce your average carbon footprint.


Examples of sources of carbon emissions for individuals include:



Your mode of transportation and how often you travel may significantly impact your carbon emissions. Driving a car, flying on a plane, and even taking public transport contribute to your carbon footprint. To put it in perspective, cycling 10km instead of driving an average passenger car over the same distance, equals an estimated 1.5kg CO2e saved*.


Energy consumption at home

Carbon emissions are generated when producing the energy that you use to power your home, such as electricity and natural gas. Heating, cooling, lighting, and appliances contribute to your carbon footprint. Using energy efficient lighting and appliances could reduce the amount of energy you consume.



The foods you eat also contribute to your carbon footprint. The production and transportation of animal products, such as meat and dairy products, typically generate higher emissions than plant-based alternatives. Removing an average of two days’ worth of meat purchases that you’d normally add to your weekly grocery shop may reduce the estimated carbon emissions from your grocery bill by approximately 4.5kg CO2e*.


Consumption of goods

The goods you buy, including clothing, electronics, and other consumer products, are often produced, and transported using carbon-intensive processes. Global fashion supply chains may be emissions intensive, especially in the production of new fashion items, which involves resource extraction, transportation, and manufacturing activities. Spending $50 on a second-hand clothing item instead of purchasing a new item is estimated to save approximately 20kg CO2e for that specific purchase*.


Waste disposal

How you dispose of waste, including food waste, paper products, and plastic, can increase or reduce your carbon footprint. When organic waste decomposes in a landfill, it produces methane, a potent greenhouse gas. It is estimated that composting 10kg of household food waste instead of sending it to a landfill may save approximately 20kg CO2e*.



4.   How do lifestyle choices affect your estimated carbon footprint?

Currently, the Westpac Carbon Footprint Tracker doesn’t consider all your environmental or lifestyle choices that may reduce your carbon footprint. The Tracker uses Australian industry data that is supplied by our partner Cogo, to calculate the estimated carbon footprint associated with eligible transactions.


Currently, the following assumptions are made in the Westpac App for the categories below:



We can't see the individual grocery items you purchase or your specific dietary choices. Therefore, we use an average Australian grocery emissions factor to calculate your estimated carbon footprint for this category.



As we don’t receive information regarding your specific meal, we use an average Australian dining-out diet emissions factor to calculate your estimated carbon footprint for this category. The estimated average operational carbon footprint of a business in this category (which includes restaurants, cafes and take-away businesses) also includes emissions from the utilities, fuel etc., generated to operate that business.


Energy and Electricity

While we can see the energy or electricity provider you use, we can’t see whether you're buying just electricity or natural gas or whether you’ve selected energy from a renewable source with your provider. We use average Australian emissions factors, which are high due to Australia's overall reliance on coal and other non-renewable energy sources.



Because we can't see the exact items or brands you purchase, we use average emissions factors based on the type of shopping category (e.g., fashion) to calculate your estimated carbon footprint, taking into account the global supply chain.


In this context, the global supply chain refers to the raw materials being used and transported between countries to create a finished product. The finished product is also generally transported between countries until it reaches the final consumer.


For Australia, most fashion items we consume are manufactured overseas, with materials sourced from across the globe. Due to the global nature of fashion, the estimated emissions factor we use represents an average weighted estimate associated with where the fashion item was made. Even fashion which is advertised as ‘made in Australia’, will likely source fabrics manufactured overseas.



The carbon footprint of flying incorporates more than just the fuel the aircraft uses. It includes the airline supply chain (i.e., processes involved to manufacture, maintain and operate the aircraft), and considers the increased emissions of having an aircraft that flies at a higher altitude.


Making sustainable living an easier choice

Supporting your choices with products, services, tips and ideas to inspire and support your sustainable living goals, no matter where you are on your life’s journey.


Do all transaction categories in the Westpac App have an associated carbon footprint?

All identified categories have an estimated carbon footprint attributed to them. For transactions where the Tracker can't identify a category, it’ll be listed as ‘Uncategorised’, with an estimated Australian average emissions factor applied, due to its specific category being unknown. This estimate is made up of a weighted average emissions factor based on the emissions intensity of all sectors in the Australian economy. It’s a good idea to re-categorise your purchase to the most relevant category to improve the accuracy of the estimate.



5.  How do your financial transactions affect your estimated carbon footprint?

With online withdrawals and transfers between accounts, transaction data indicates that typical transactions in this category involve moving money between accounts, meaning they could incur a zero carbon footprint or one that is relatively smaller than transactions in other categories.


While with other financial transactions like mortgages and loan repayments, rent, ATM withdrawals and financial services, they’ll be allocated an estimated carbon footprint as follows:


Mortgages, Loans & Rent Payments

Take into account the carbon footprint of the organisation (the bank or your landlord) you're paying money to, including their operating costs, capital expenditure, and investments. All of these services have a carbon footprint.


Withdrawals from ATMs

We’re not able to see what you buy with the money you withdraw from an ATM, so we use an emissions factor based on average Australian household spending. To increase the accuracy of the estimate, we encourage you to re-categorise your ATM withdrawals to show the most relevant category for that transaction.


Investments & Shares

We don't have visibility over what your money is invested in, so this calculation is based on the estimated average emissions of entities that our partner Cogo considers forming part of the Australian financial services industry. We assign this emissions factor to transactions that are categorised as ‘Investments & Shares’ in your transactions list.



6.  How does your estimated carbon footprint compare to others?

To compare your estimated carbon emissions in the Westpac App for any transaction category, the Carbon Footprint Tracker provides averages for both Australian individuals and households that Cogo has sourced.


It’s important to remember that every individual's carbon footprint is only an estimate based on certain eligible transactions. It doesn’t consider all their day-to-day activities and lifestyle choices that may impact their overall personal carbon footprint.


The important thing to note is that taking small, positive actions can help if you are interested in understanding the potential to reduce your carbon footprint.

What steps can you take to lower your estimated carbon footprint?

To give you an idea, every $2 spent at an Australian fashion retailer creates, on average, 1kg CO2e, the equivalent of driving an average car 5.5km*. Certain industries and companies are more sustainable than others and have lower carbon emissions. For example, renewable energy providers and second-hand fashion retailers have a much lower impact on your footprint than non-renewable energy providers and buying new clothes.


By understanding how your spending contributes to your carbon footprint, you'll be equipped with the information needed to make spending choices that may help manage your carbon footprint.


Quick tips that may help reduce your carbon footprint

From riding a bike instead of taking your car to limiting your showers to just five minutes, discover the small changes you can make to help reduce your carbon footprint.


Things you should know

Read the Westpac Online Banking Terms and Conditions (PDF 448KB) at before making a decision and consider whether the product is right for you.


This information is general in nature and has been prepared without taking your objectives, needs and overall financial situation into account. For this reason, you should consider the appropriateness for the information to your own circumstances and, if necessary, seek appropriate professional advice.


Last updated 1 Nov 2023.

* The information provided relates to environment, social and governance (ESG) topics, including but not limited to climate change, targets, projections, scenarios, and other proxy data. Carbon footprint estimates are calculated based on industry averages and aren’t specific to individual purchases or merchants. The calculations compare transactions conducted via eligible Westpac accounts against industry data provided by Connecting Good Australia Pty Limited (Cogo). Transactions categorised as pending or transfers aren’t included. All facts and C02e values are estimates provided by and published with the permission of Cogo. The information is based on research at an industry level and will be updated as more information becomes available, and Cogo is responsible for its accuracy and completeness. Westpac gives no representation, warranty or guarantee (including as to the quality, accuracy or completeness of this information). Actual outcomes may differ from those expressed or implied.

For transactions made in a foreign currency, we apply the relevant emissions factor to the converted AUD (Australian Dollar) amount based on the category the spend has been assigned to. To learn more about how foreign currency transactions are converted, tap on the link below.

Learn more

For more information on Cogo, visit their website.

Read our Privacy Statement for more information about how we handle your personal information.

© Westpac Banking Corporation ABN 33 007 457 141 AFSL and Australian Credit Licence 233714.