Know the climate impact of an experience before you book it.
See an indicative kg CO2e estimate per participant for tours, boat trips and workshops — computed privately in your browser.
No account. No tracking. Zero network requests.
Page
Sunset Boat Trip on the Tagus
~ 3.4 kg CO₂e
per participant
High confidence49% above the typical estimated impact of similar experiences (boat tour)
- ·Route distance not stated on the page. Using the boat tour default of 18 km.
- ·Group size not stated. Using the small-group default of 12 participants.
- ·One tasting-size food serving assumed for this experience.
- ·Participant travel to and from the experience is not included.
Indicative estimate. Not a verified footprint or sustainability certification.
Estimates, not certificates.
Carbon Lens never claims to measure or certify. Every number is an indicative estimate, and it says so.
Every assumption declared.
When a page does not state duration, group size or distance, the default we use is listed, explained, and editable.
Zero network requests.
The extension contains no network code at all — verifiably. Every estimate is computed locally in your browser. No servers, no telemetry, no accounts.
Works everywhere
Marketplaces like GetYourGuide and Viator, or operators' own websites.
Per participant
The number that matches how you actually book.
Full breakdown
Transport, energy, food and materials, each estimated separately.
Confidence badge
High, medium or low, depending on how much came from the page vs. category defaults.
Four languages
Understands pages in English, Portuguese, Spanish and French.
Edit and recalculate
Adjust duration, group size, distance, food servings or transport mode; the estimate updates instantly.
Methodology
Carbon Lens is fully deterministic: no server, no black box. The same page always produces the same estimate, for every user. Here is exactly how it is built.
Read
Extracts the page's public content: JSON-LD structured data (Product, TouristTrip, Event), title, meta description and visible text. Nothing leaves the browser.
Classify
Ordered multilingual keyword rules identify the experience type (12 categories) and parse duration ("2 hours", "90 minutes", "half day", ISO 8601), group size ("up to 6 people", "small group"), route distance, food servings, indoor venues and materials. Title and structured data outrank body text, so cross-sell links never flip the category.
Calculate
Motorised transport = (vehicle factor × km) ÷ group size; indoor venues use electricity per person-hour; food per serving; materials per person. All factors live in one open configuration file.
Compare
The result is benchmarked against the typical estimate for its own category, always phrased relatively ("X% below/above typical"), never as an absolute sustainability claim.
The factors, in the open
| Factor | Value | Unit | Basis |
|---|---|---|---|
| Venue electricity | 0.11 | kg CO₂e per person-hour | ~1 kWh per visitor-hour × Iberian grid intensity 2024-25 |
| Electric vehicle (e-tuk) | 0.02 | kg CO₂e per vehicle-km | ~0.15 kWh/km incl. charging losses × grid |
| Fuel tuk-tuk | 0.18 | kg CO₂e per vehicle-km | Between light auto-rickshaw studies and DEFRA 2025 average petrol car |
| Segway | 0.04 | kg CO₂e per person-hour | Battery/range specs × grid |
| Boat | 2.5 | kg CO₂e per vehicle-km | Mid-range of mixed sightseeing fleets (sail ~0.3 to RIB ~6) |
| Food serving | 1.1 | kg CO₂e per serving | Tasting-size portion of a mixed menu (Poore & Nemecek data) |
| Materials (low/medium/high) | 0.15 / 0.6 / 1.5 | kg CO₂e per person | Anchored in ceramic tile LCA |
Known limitations
The estimate excludes participant travel to the venue, embodied assets and menu detail. Boat factors span a wide real-world range, so results for boat trips are the least precise. The benchmark derives from our own category defaults, not from an external dataset. Sources: DEFRA/DESNZ 2025 conversion factors, Iberian grid intensity data, Poore & Nemecek 2018, and published LCA studies.
Questions
No. Carbon Lens produces indicative estimates from public page information only. The disclaimer is permanent and shown with every result.