We simplify estimation of

Carbon Emissions

​From freight shipments to commuting, organizations trust CarbonSutra to calculate carbon footprint of their operations.

Simplifying Emissions Management for Organizations

CarbonSutra estimates the Scope 1/2/3 greenhouse gas emission footprint for your organization, backed by transparent data sources and algorithms. IT divisions of companies and independent developers of emissions management, carbon measurement calculators, accounting, sustainability metrics and ESG systems are the main users of this comprehensive API set and spreadsheet functions. 

The footprint of business travel by air is calculated based on the distance between airports and the traveling class. With the origin and destination as inputs and following the ICAO methodology along with GHG/EPA emissions factors, we apply appropriate rules based on IPCC's research.

The footprint of a hotel stay is calculated based on CHSB 2026 index and UK Government's GHG conversion factors. Based on the country and optionally entered city/region along with the rating of the hotel, the emission is calculated. Covers 40 countries.

Emissions from primary fuel sources combusted at a site. The emission factors are divided into the usage of fuel (commercial, industrial, transport and residential) for accurate estimations.​​
The freight/shipping emission estimations are for Road, Rail, Air and Sea along with intermodal shipping combinations. Recommended average emission factors and guidelines from ECTA and Cefic are used.
An advanced algorithm to estimate the emissions of a package's journey. Using the combination of land transport to nearest airports and freight transfer through air, it works on a database of over 1.5 million postal codes across 95 countries and 9,200 global airports.
In this variation, the footprint of a passenger vehicle based on its category (i.e., type or size) for a specific distance is calculated. This API is also used for employee commuting and travel in vehicles like motorbikes, taxis, buses and trains.
We calculate the footprint of a passenger vehicle based on its make and model for a specific distance. Over 140 makes of vehicles covering 4,500 models are covered.​​
This computes the emissions from electricity used by an organization, usually reported as Scope 2 indirect emission. Data from nearly 90 countries from multiple sources has been compiled. 

Developers Love CarbonSutra {Immediate trial on any platform}

  • Instant Trial
  • Platform Support
  • Free Start
  • Clustering Calculations
  • Integration Support
Every API of CarbonSutra can be immediately (and freely) tested using a browser and a Google, Github or Facebook ID. Each API is extensively documented and supplemented with examples. The environment will guide you on the value of every input field and all outputs has values of CO2e of gm, kg, tonnes and lbs. Advance functionalities like clustering can also be seen in action without writing a single line of code. CarbonSutra API can be accessed from multiple platforms hosted globally, and can be easily tested at RapidAPI.
As you test CarbonSutra, it automatically creates code snippets of that Endpoint in all common programming languages. A copy/paste of the snippet into your application will make it running in minimum time. Currently, the following are supported: ​C (Libcurl), Clojure (clj-http), C# (RestSharp, HttpClient, Unirest), Go (NewRequest), HTTP (HTTP/1.1), Java (OkHttp, Unirest, AyncHttp, java.net.http), JavaScript (jQuery, fetch, Axios, XMLHttpRequest), Kotlin (OkHttp), Node.js (HTTP, Request, Unirest, Fetch, Axios), Objective-C (NSURLSession, Unirest), OCaml (CoHTTP), PHP (cURL, HTTPv1, HTTPv2, Unirest/Request), Powershell (Invoke-WebRequest, Invoke-RestMethod), Python (http.client, Requests, Unirest), R (httr), RapidQL, Ruby (net::http, Unirest), Shell (cURL, HTTPie, Wget) and Swift (NSURLSession).
- The API is free if you have up to 200 requests per month. We have an increasing number of small companies who are comfortably using this plan. This is also ideal for ISVs providing freemium options. 
- The API is free if you are a charitable or non-profit organization, irrespective of the usage. Just contact us directly. 
- Only for large commercial organizations or those making more than 200 API calls per month, there is a paid option. 
Clustering the results of APIs within CarbonSutra eliminates the need to store the emission calculation results on developer's side. Let's say, a company calculates emissions for business travel (air and land), electricity consumption, hotel stays and their vehicle fleet, once every quarter, Using only a self-defined label as a input parameter, these calculations can be clustered into sets and retrieved in future. This feature is heavily used by programmers who use clusters to monitor emission trends, compare data across periods and offset. 
All CarbonSutra customers have access to our developers and code of sample applications that accelerate the learning widen the possibilities. Our customers have integrated these APIs from simple mobile applications to large applications running on SAP and Oracle backends. We have worked closely with them to help in the integration process, discussed our algorithms and brainstormed approaches to solve challenges. For smaller installations, we have integrated CarbonSutra into Excel spreadsheets and provide this code to them for free, who then calculate their carbon footprints without coding. ​

Auditors Love CarbonSutra {Dynamic API explanations}

For sustainability managers, accountants and ESG auditors, a carbon footprint calculation is only as good as the methodology behind it. In the era of CSRD and strict compliance, "black box" numbers raises more questions. Every single calculation generated by our popular APIs doesn't just return a raw data points —it appends a clear, mathematically complete, and compliance-ready "explanation" field. 

Sample Output of Business Travel

{
  "data": {
    "type": "estimate-travel-flight",
    "airport_from": "Tokyo Haneda International Airport",
    "airport_to": "Los Angeles International Airport",
    "flight_class": "Business",
    "round_trip": "N",
    "add_rf": "Y",
    "include_wtt": "Y",
    "co2e_gm": 3212668,
    "co2e_kg": 3212.67,
    "co2e_mt": 3.21
  },
  "success": true,
  "status": 200
}

"explanation": "This emission profile is computed using the UK Government's 2026 conversion factors for greenhouse gas (GHG) reporting. The calculation is for a single passenger travelling in Business class between Tokyo Haneda International Airport(HND) and Los Angeles International Airport(LAX). The distance between these airports is estimated at 8,812 km, utilizing the Haversine equation for Great-Circle Distance (GCD). Radiative forcing uplift is included and indirect/WTT factors are added, as per inputs. For this one way journey, the total footprint evaluates to 3,212,668 grams of CO2e. Standardized metric conversions render this as 3212.67 kg (rounded to two decimal places) or 3.21 metric tons. Scaled against imperial baselines using the conversion factor of 2.20462 (source: GHG conversion factors, 2026), the final metric is expressed as 7082.72 lbs."

Sample Output of Hotel Stay

{
"data": {
"type": "estimate-hotel-stay",
"country": "India",
"city_name": "Mumbai",
"hotel_rating": "4",
"number_of_nights": "3",
"number_of_rooms": "1",
"co2e_gm": 182160,
"co2e_kg": 182.16,
"co2e_mt": 0.18,
"co2e_lb": 401.59
},
"success": true,
"status": 200
}

"explanation": "CarbonSutra uses the Cornell Hotel Sustainability Benchmarking Index 2026 (CHSB2026) for this calculation, specifically leveraging the mean value from the CHSB validity test for Measure 1 - HCMI Room Night Emission (Carbon Category). Because specific emission factors for Mumbai are unlisted in CHSB2026, fallback data for India has been applied to this calculation of one room and 3 nights. This methodology relies on the Expedia Star Rating classification system. Where regional data gaps exist, proxy assignments are made according to the transparent governance rules published on carbonsutra.com. For the hotel rating of four stars, an emission factor of 60.72 kgCO2e per room night is used. This footprint evaluates to 182,160 grams of CO2e. Standardized unit conversions render this as 182.16 kg (rounded to two decimal places) or 0.18 metric tons. Scaled against imperial baselines using the conversion factor of 2.20462 (source: GHG conversion factors, 2026), the final metric is expressed as 401.59 lbs. "

About Us

We are a team of experienced professionals with formal education in ClimateTech and have consulted reputed global organizations in data challenges across decarbonization pathways, emissions management and connected systems through custom APIs.

CarbonSutra is a part of Contactous, which is a Singapore registered organization serving global customers since 2016, specializing in data deduplication of large datasets, complex entity resolution algorithms and contact data management. 

CarbonSutra has been used for millions of calculations and we have a rich roadmap for CarbonSutra with dozens of specialized algorithms planned to be released in future. For special solutions, these calculations have been integrated with GenAI projects and we plan to launch their generic version in future. 

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