How this compares

What else you could use to work out your emissions. What each one is good at, and when you should pick it over us.

Why we name no names

We describe what each kind of tool does instead of naming brands. Partly that’s caution: a comparison table written in September is wrong by March, and somebody else’s product ends up misrepresented on our page. Partly it’s that the category matters more than the brand. There are a dozen cheap carbon calculators and they mostly share the same strengths.

You’ll recognise the one you’re weighing up. If you want a straight opinion on a product you’re actually looking at, ask us and you’ll get one.

What you are choosing between

Five of them. Most small businesses are picking between two, without ever having named the other three.

A spreadsheet

Where most small businesses actually are, and there is nothing daft about it. You type the numbers off your bills, paste the factors out of a government PDF, and add it up.

Good at.: Free, and everybody can read one. The whole sum sits on the screen where you can check it. For one site and one year, a spreadsheet is often the quickest way to a right answer.
Where it runs out.: It does not remember why a number is what it is. When the electricity factor gets revised, last year’s total quietly changes with it, and you can no longer show a customer what you actually sent them. Getting figures out of four other people means emailing the file around and merging their edits by hand.

The free national route

A government-backed platform. You sign in with your business digital ID and it pulls your electricity, water and gas straight from the agencies that already hold them.

Good at.: Free, official, and you do not type the numbers — they arrive, and they are right. If a national programme or a big customer has asked you for a simple disclosure, this is the thing they mean. Use it.
Where it runs out.: It only works in the country that built it. Run a site over the causeway and you need a second answer for that one. What comes out is a disclosure in that programme’s format, which is what the programme wants. The customer who asks how you got the number is asking something else.

Big enterprise software

Serious kit for a company with its own sustainability team. Enormous factor libraries, plugs into your accounts and your meters, handles several companies at once, chases your suppliers, and feeds an auditor.

Good at.: Honestly better than us at nearly everything. Above a certain size it is the right call. The checked methods, the audit-ready paperwork and the worldwide coverage are real, and that part is not marketing.
Where it runs out.: Priced and built for a company that pays somebody to run it. The whole thing assumes one named person owns this job. If nobody in your building does, it keeps asking questions nobody can answer.

A cheap carbon calculator

A small monthly fee, a wizard that walks you through Scope 1, 2 and 3, and a dashboard with your total on it. The biggest group, and the fastest growing.

Good at.: Cheap, quick, and upfront that it is an estimate. If you want a rough number to start a conversation, that is a fair trade. Some of them are a pleasure to use.
Where it runs out.: Most of them work off industry averages and how much you spent, and few will tell you which factor produced which line. That is fine right up until your customer’s auditor asks where a number came from. Then it gets done again, properly.

A consultant

A person who sits down with you, does the counting, writes the report, and usually knows your trade. Still how most first reports around here get written.

Good at.: Judgement. Working out what actually matters for your business, what you can stand behind, and what to do about the answer — that is skilled work, and no software has replaced it. A good consultant beats bad software.
Where it runs out.: It does not build up. When the job ends the know-how walks out with them, next year starts near where this year started, and you pay again. We do consulting too, so we are saying this about ourselves.

Where we fit

We built EsgaSIS on one bet. The arithmetic is the easy part. What’s hard is getting the numbers out of the five people who happen to hold them, and then having the answer stand up when somebody questions it.

Five things follow from that, and they are more or less the whole product.

We ask whoever has the bill. Eight sets of questions, each one named after the person who actually holds that information. Whoever pays the electricity. Whoever runs the vans. The kitchen. You send them a link that expires, they fill in their bit, and they need no account and no password. Nobody in a small business knows what "Scope 3 Category 5" means. Everybody knows who keeps the gas bill.
Every number shows its working. Which factor we used, who published it, which year it came from and how we picked it, saved onto the entry the moment you hit save. When the published factors change next year, your old report still says what it said.
When we do not know, we say so. Rubbish, water and electricity work differently from one country to the next. One place burns its waste, the place next door buries it. So we won’t quietly borrow a factor from somewhere else, or fall back on a world average. Where there is no proper factor you get no number, and a written note saying why. We would rather hand your customer that than a wrong figure.
You cannot tick a box to claim more than you have done. Whether your report says "with reference to" or "in accordance with" the GRI Standards gets worked out from what you have filled in, and checked again on our server when the report is made. There is no dropdown. One unverified factor and the bigger claim is off the table.
Malaysia and Singapore, both done properly. Not one country with an export button. We handle them separately, and by region: the electricity factor in one Malaysian state is about half its neighbour’s, which is a reporting mistake rather than a rounding one. Work both sides of the causeway and you do not need two tools.

We have few factors, on purpose

We hold 54 of them. Every commercial platform quotes a much bigger number, so it is worth answering.

A big library genuinely matters if you buy from all over the world and do a hundred different things. Run two shops in Singapore and you will touch maybe eight factors, ever. What matters about each of those eight is whether it is the right one: right publisher, right year, right state. Every factor we hold has either been checked against the original source, or it is flagged unverified and blocked from any finished report.

That includes three Malaysian electricity factors we found were wrong last September. Not slightly wrong. We corrected them and wrote up what happened.

More factors would let us cover more kinds of business. They would not make today’s numbers any easier to defend, and coverage is the easier of those two to fix later.

Go somewhere else if

These are the times another tool is the better answer. They are the same shortcomings we list on the methodology page, put here as decisions rather than as small print.

All you need is the free national disclosure. Then use that. It is free, it fetches your usage for you, and it is what the programme is asking for. Come back when a customer asks how you got the number.
You buy green electricity. We count the grid average, so a green tariff or renewable certificates will not show up in your figure. You paid for something and we will not show it. That is a real gap and we are working on it.
You need to show you have improved on last year. We do not do year-on-year yet. The line about reducing emissions comes out empty, and there is nothing to set a target against. A first count is genuinely useful. A second one is not, yet.
Your auditor wants to see the bills. You cannot attach the electricity bill to the electricity figure. Every sum is traceable and the paperwork is not there at all.
You have a lot of sites, or you are outside Singapore and Malaysia. One company, one boundary, no splitting by branch, two countries. Use a bigger platform. This is not a close call.
You are listed, or your parent reports to investors. We are built around GRI. If what you owe is an investor-facing climate disclosure, your emissions numbers carry over but the report does not, and you want something built for that.
You need the footprint of a product, not the company. We do not do it and we are not planning to. A per-item number ends up printed on a packet, and that deserves software built to stand behind it.

You can use more than one

These are not either-or, and treating them as one choice is the commonest mistake we see. For a lot of Singapore businesses the sensible answer right now is to do the free national disclosure because somebody asked for it, and keep a proper counted inventory alongside it for what comes afterwards: the supplier questionnaire, the bank, the customer whose own auditor is asking awkward questions.

Our own working through TR 149:2026 goes into that in detail, including the parts of it we are no use for.