# Dynamic Explanation of Calculations

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."*