Method and sources
Every figure on this site comes from this page. If a number is not here, it is not on the site.
The four calculations
| Output | Formula |
|---|---|
| Energy | messages/day x Wh/message / 1000 x 365 |
| Water | messages/day x mL/message / 1000 x 365 |
| Carbon | kWh x 0.37 kg CO2/kWh |
| Cost | kWh x 18.17 cents/kWh / 100 |
Sources
| Organisation | Date | Scope | |
|---|---|---|---|
| Joule (2026), summarised by Global Footprint Network | 2026-08 | operational energy per query at production scale | link |
| arXiv 2505.09598, How Hungry is AI? | 2025-05 | per-query inference energy, benchmarked per model | link |
| OpenAI (Sam Altman), as reported | 2025-06 | on-site data centre cooling water only | link |
| Google, Gemini technical report, as reported | 2025-08 | on-site data centre cooling water only | link |
| Microsoft, cited in Joule, as reported | 2025 | on-site cooling water | link |
| UC Riverside (Ren et al.), as reported | 2023 | life cycle including water used to generate the electricity | link |
| Mistral, life-cycle assessment, as reported | 2025-07 | full life cycle for a 400-token answer | link |
| US Energy Information Administration, Form 861M | 2026-08 | US residential average retail price | link |
| US Energy Information Administration, FAQ 74 | 2023 data, published 2026 | US average generation emissions | link |
What this site does not do
It does not measure your account. It does not know which model served any particular reply. It does not include training runs, hardware manufacturing, or the embodied cost of the buildings. Those are all real, and all excluded here because they are not attributable to a single message.
Known weaknesses
Per-prompt water divides a facility total by a query count, which produces an average that no single conversation consumed. Per-prompt energy comes from benchmarks rather than from production traffic, so it measures a standardised prompt rather than yours. The grid factor is a national average; a query served in a coal-heavy region carries more, and one served in a hydro-heavy region carries less.
These weaknesses are why the calculator shows ranges. A single number would hide exactly the uncertainty that makes the topic worth writing about.