DIY guide to carbon calculators for SMEs and startups
- Published on
- 4th May 2025
⬇️ If you would like to understand what tools are available for calculating your SME or startup carbon footprint for the first time, read on!
➡️ If you’re not sure what a carbon footprint is, or how it works, first check out our climate change page to get your head around the basics.
Why you may need to use a carbon calculator
Maybe one of your big clients is asking you to report your carbon footprint to them. Or perhaps you need to report your footprint as part of trying to win new work, or maybe it’s a new regulation that now applies to you.
Where to start? Here are the key principles.
Not all carbon calculators are equal
Calculating a corporate carbon footprint comes with a lot of nuance and technical methodology, and if you’re not careful, you may end up with a very inaccurate footprint. This might lead you to reporting wrong information (which, depending on where you’re reporting to, may have its own various consequences), and will be useless in helping you determine a good carbon reduction plan.
For example, using a calculator based on UK energy figures will spit out bad data if you’re a business based in the US. Geography matters! Your sector matters too – if most of your carbon impact is with your suppliers, a calculator only focusing on Scope 1 and 2 emissions will miss all of your emissions in Scope 3 (the Scope that’s most relevant for you).
However, using the right online calculator for your business is an excellent starting point to mapping out and reporting your carbon footprint. It will give you a good enough understanding of where your biggest emissions are coming from, and point you to where taking action would likely be most effective.
Good enough is better than perfect
Climate action does not require perfection. It’s actually much better to begin taking action quickly off of reasonably good information, than waiting a long time for a perfect carbon footprint before getting started. Climate change is a time sensitive problem.
So you don’t need to invest big budget into your carbon footprint if that’s just not feasible. Use this guide to find the right free or low-cost calculator, so you can get going on what actually matters – swift, meaningful action. Taking this approach will help you be seen as a credible, serious business in your clients’ eyes.
How does a carbon calculator work?
A carbon calculator is a tool that allows you to input your carbon-emitting business activities, like electricity usage, miles driven, flights taken, goods purchased, etc. It then applies the right calculations in the background to convert these activities into your carbon footprint. There’s an internationally agreed methodology for these conversions called the Greenhouse Gas Protocol.
The calculator will tell you the total CO2 emissions (or CO2e – carbon dioxide equivalent) in KGs or Tonnes, and will often break the total out into different categories, so that you can see where the biggest emissions are coming from.
What am I expected to do with the information the carbon calculator gives me?
You can then use this information to understand where you can tweak your business to lower your emissions. For example, can you switch from flying to taking the train, or can you switch to purchasing renewable electricity instead of fossil fuel-based electricity, etc.
It’s best to focus on lowering your biggest emissions first, but keeping it within the realm of what’s realistic. You may have some quick wins that are easy to change, but there may also be some big emission areas that may take you years to change. This is expected and normal.
Which carbon calculator should I use?
Many different calculators are available online – some are free, some are paid, some cover a specific region, some focus on specific types of activities.
We’ve created this guide to help you make sense of everything and find the calculator that’s right for your business, so you end up with as accurate and credible of a carbon footprint as possible (without hiring expensive consultants).
Here are the key elements to consider when choosing a carbon calculator:
- Does it cover all your main business activities: Take a look at the inputs the calculator asks for, and ensure that no major part of your business is missing. You know your business best. If you’re a consultancy relying on lots of travel to client sites, ensure the calculator asks for this data (flights, for example). If you’re a manufacturer that purchases a high volume of inputs to make your products, ensure the calculator covers this, too (purchased goods, for example).
- Does it cover your geographic location(s): The amount of CO2 emitted to produce electricity varies widely across countries. Some countries use quite a lot of renewable energy, and this means that the CO2 emissions associated with businesses using this energy are lower. While other countries may not have any renewables in their electric grid, so businesses operating in these locations will be in turn emitting more CO2. Ideally the calculator you use will allow you to input your business activities by country, so it can apply geography-specific figures to your business.
- Does it ask for the right level of granularity: Some calculators ask for very detailed inputs, like data from utility bills. Others are set up to use industry averages and estimations, allowing you to bypass entering information that’s very specific. Of course the more accurate detail you can enter, the better – but if that’s simply not feasible, choose a calculator that will help you along by substituting with averages and estimates.
- Is it using the Greenhouse Gas Protocol methodology: Check in the calculator’s description or T&C’s for this. The GHG Protocol is the main internationally agreed methodology for estimating business carbon footprints.
- What extra bells and whistles could you benefit from: Can the calculator save your information so that you can go back annually to update and track your reductions? Can it suggest an action plan based on your results? Check out what useful features it may provide and if these are useful to you. But be wary if it offers to ‘offset’ your emissions so you can become ‘carbon neutral’! Offsetting is not the easy solution providers like you to think it is.
What else to keep in mind:
- Start small: Begin by focusing on Scope 1 and 2 emissions, which are often simpler and easier to calculate. Once you have your head around these, you’ll be more ready to tackle Scope 3. Familiarize yourself with the Greenhouse Gas Protocol if you’re not yet sure what is meant by Scopes 1 – 3.
- Be transparent: Always include information about how you calculated your footprint alongside reporting it. Did you use a specific calculator? Did you leave out any key business activities from the data? Did you have to estimate or ‘ballpark’ any of the inputs? Which financial year did you use for the calculations? All of this provides useful context to the receiver of the information to interpret it correctly, and avoids greenwashing.
- Work with an expert: If you can, work with a carbon accounting expert. You may not be able to afford to pay a big consultancy, but there are also many freelancers and SME-focused NGOs that can help you, sometimes as part of an SME course. They may be low fee or no fee, so it’s worth exploring these options. You can find many of them in our databases.
- Follow a recognised standard: Ensure that whatever tools you use are based on the GHG Protocol. This makes sure that your approach is aligned to how all other businesses calculate their footprints. It also allows you to report your data in a standard way, and to be transparent and credible about your approach.
How to get started
Use a good AI prompt to find the
right calculator for you
We’re all about working smarter, and not harder. Now that you understand the fundamentals and have your own good judgment about what works and what doesn’t, we recommend using a good prompt to narrow down your calculator options.
Try it out – paste the following prompt into an AI app of your choice and tweak based on your own requirements:
Which are the best 3 corporate carbon calculators for my small business? Please use the following criteria to narrow them down:
must be suitable to [insert your sector],
must be free,
must cover site locations in [geography X and Y],
must be based on the GHG Protocol,
and [does not require detailed invoice data entry].
It should cover all 3 scopes.
Of course all the typical disclaimers apply to this advice! Always use your own good judgment, and treat AI as an additional helpful tool, rather than an absolute accurate answer.
The usefulness of AI outputs heavily depends on how well you craft your prompt, including all necessary details and ensuring good structure. If you use an identical prompt with different AI apps, you’ll get different results. That’s because different AI models are structured differently, and may need differently structured prompts.
To help you get the best outcome, here are model prompts optimised for some of the most popular AI tools. Ensure you tweak them to your own needs.
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I am looking for the best carbon footprint calculator tailored for my business. Please help me find or recommend tools that are optimized for my specific needs. To provide accurate suggestions, here are the details of my business:
Industry Type: (e.g., manufacturing, tech, retail, agriculture, etc.)
Size of Business: (e.g., small, medium, large, number of employees)
Location: (If relevant, include country/region as carbon factors can differ by geography)
Primary Operations: (e.g., transportation, energy consumption, supply chain, waste production)
Data Requirements: (e.g., Do you need a calculator that requires manual input or one that can integrate with existing software like CRM or ERP systems?)
Purpose: (e.g., sustainability reporting, reduction targets, customer engagement, compliance with regulations)
Budget/Costs: (e.g., free options, affordable, premium services, or enterprise-level tools)
Integration Preferences: (e.g., integration with other tools or platforms, ability to track emissions over time, API access)
Additional Features: (e.g., data visualization, reports, dashboards, goal setting, benchmarking, etc.)
Based on these details, can you suggest a carbon calculator that fits my business, and explain the key features that make it a good match for my needs?
“My business is a size [X] company in [X] sector, operating in [region].
I need a carbon calculator that covers Scope 1, 2, and 3 emissions, aligns with GHG Protocol, and ideally integrates with our accounting software.
Please provide a comparison table of the best business carbon calculators, including: data input requirements, methodology transparency, usability, compliance support, and export/reporting features.
Highlight the pros and cons of each option, and recommend the best fit for my needs.”
“I’m looking for the best carbon calculator for my business, which is a [SPECIFY YOUR INDUSTRY, e.g., small e-commerce retailer, medium-sized manufacturing company, service-based consultancy] with approximately [SPECIFY NUMBER] employees and an annual revenue of roughly [SPECIFY REVENUE RANGE or APPROXIMATE FIGURE].
Our key operational areas that contribute to our carbon footprint include [LIST KEY AREAS, e.g., office energy use, employee commuting, shipping of goods, supply chain, data center usage, business travel].
My priorities for a carbon calculator are:
Accuracy and Reliability: It should use robust methodologies and provide trustworthy results relevant to [SPECIFY ANY INDUSTRY-SPECIFIC STANDARDS OR REPORTING REQUIREMENTS, e.g., GHG Protocol, ISO 14064].
Ease of Use: The interface should be intuitive and not require extensive technical expertise.
Specific to [YOUR BUSINESS TYPE/SIZE]: It should be tailored to the needs and scale of a [USE YOUR SPECIFIED BUSINESS TYPE/SIZE AGAIN].
Actionable Insights: The calculator should not just provide a number but also suggest concrete steps and strategies for reducing our carbon footprint in areas like [MENTION SPECIFIC AREAS AGAIN, e.g., energy efficiency, sustainable sourcing, transportation optimization].
Cost-Effectiveness: Please consider both free and paid options, highlighting the value proposition of each.
Integration Capabilities (optional but desirable): Ideally, it could integrate with our existing [MENTION ANY RELEVANT SOFTWARE, e.g., accounting software, CRM, supply chain management tools].
Reporting Features: It should offer clear and customizable reports suitable for [SPECIFY YOUR REPORTING NEEDS, e.g., internal stakeholders, potential investors, public disclosure].
Based on these requirements, can you recommend specific carbon calculator tools or platforms and explain why they might be a good fit for my business? Please also highlight any potential limitations or considerations for each recommendation.”
Browse our curated list of carbon calculators
The limitation of AI is that it will highlight the most prominent (and most marketed!) tools to you. If you want to ensure you’re getting a holistic view of what’s out there, including more niche or new options – that’s what our database is for!
We’ve compiled a list of the most popular and trustworthy calculators in our database. Browse them below to find suitable ones for your business.
Try these carbon calculators for estimating the overall carbon footprint of your small business or startup.
LilMa Green Advanced Micro Business Carbon Calculator
Practical and manageable for small businesses, and aligned to key standards.
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LilMa Green Simple Micro Business Carbon Calculator
Designed specifically for small and micro businesses, and with options for advanced or simple calculations.
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Plan A free carbon footprint calculator for business
Free carbon calculator, including all three scopes.
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myclimate carbon calculators
myclimate provides a free online carbon calculator for flights, events, car trips, cruises, households, and organisations.
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The Carbon Footprint Small Business Calculator
Measure the carbon footprint of your small business with this calculator by Sustrax.
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Small Business Carbon Calculator
A simple carbon calculator for small businesses, aimed at those just getting started.
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SME Carbon Footprint Calculator
Credible way to measure Scope 1 and 2 for small UK businesses.
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Simplified GHG Emissions Calculator
Credible GHG calculator for small businesses, especially in the US.
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Calculator for Small Businesses by Small99
Get 5 climate actions your business can take in just 3 minutes.
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Corporate carbon footprint calculator
Free rough corporate carbon footprint tool by CarbonChain, an easy way to get started.
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Try these carbon carbon calculators to calculate the footprint of a specific event or activity
LilMa Green Scope 1-2 Emissions Calculator
Practical and simple for small firms in the UK.
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GHG Equivalencies Calculator
Convert emissions or energy data into concrete terms you can understand — such as the annual CO2 emissions of cars, households, and power plants.
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myclimate carbon calculators
myclimate provides a free online carbon calculator for flights, events, car trips, cruises, households, and organisations.
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Website Carbon Calculator
Measure your website’s environmental impact.
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Julie’s Bicycle Creative Climate Tools
A free set of unique carbon calculators developed by Julie’s Bicycle specifically for the cultural sector.
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Digital Emissions Calculator by Small99
Get an estimated figure of your annual digital emissions, like email, virtual calls and website.
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Looking for something else?
Search through hundreds of useful tools in our ESG tools database.
SME-friendly consultancies for carbon footprinting
Need an expert? These consultancies, specialising in small businesses and startups, can help.
The Sustainable Life Coach
Locations:
NorthPeak Advisory
Locations:
Positive Planet
Locations:
The Sustainability Network (TSN)
Locations:
Sustainer
Locations:
Grain
Locations:
TripleWin Advisory
Locations:
RyeStrategy
Locations:
Peterson
Locations:
Ellipsis Energy
Locations:
Eco Plan
Locations:
:response
Locations:
Are you a consultancy that should be listed here? Get added to our ESG Service Provider database.
Prefer a supportive community?
These SME communities can support you, and you can work along-side your peers
SME Sustainability Hub (UNGC Switzerland & Liechtenstein)
Holistic and strategic approach to ESG for SMEs in Switzerland and Liechtenstein.
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SME Climate Hub
Free tools for business climate action.
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Heart of the City
If you’re an SME in London or in the UK, you can apply to join upskilling programmes run by Heart of the City to get your responsible business journey started.
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Are we missing a great carbon accounting resource?
Let us know and we’ll add it.
Essential reading for SMEs
Read these guides for a better understanding of how to take climate action
Climate Contribution Hub
Free-to-use six-step process for cutting carbon footprints and taking responsibility for ongoing emissions. Perfect for SMEs.
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SME Sustainability Ecosystem
Quick way for UK SMEs to understand where to go for help to tackle their carbon footprint.
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Better business guide to energy saving (by Carbon Trust)
New to energy saving? This guide helps you identify measures where energy and cost savings can be easily made with little or no cost.
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The journey to Net Zero for SMEs (by Carbon Trust)
This guide provides small and medium sized enterprises (SMEs) with a pathway to Net Zero. It introduces the simple options available to SMEs beginning their Net Zero journey and highlights the challenges in the long term.
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Access: