~/.claude/water-log.jsonl hereWater flows through: effective token count → model multiplier → water rate (low / mid / high). All three scenarios are always reported — never just one number.
| Scenario | Rate | WUE | Basis |
|---|---|---|---|
| Low (optimistic) | 0.000036 | 0.18 L/kWh | AWS modern, cool climate |
| Mid (central) ✶ | 0.00036 | 1.8 L/kWh | ML.ENERGY 2025 US average |
| High (pessimistic) | 0.00079 | 4.0 L/kWh | Hot climate, older facility |
✶ Charts and main values show mid. The low–high band reflects WUE uncertainty across different data centre locations. Anthropic does not disclose which AWS regions handle inference.
| Model | Output price | Multiplier |
|---|---|---|
| Haiku 4.5 | $5/MTok | 0.33× |
| Sonnet 4.5 | $15/MTok | 1.00× |
| Sonnet 4.6 (baseline) | $15/MTok | 1.00× |
| Opus 4.5–4.8 | $25/MTok | 1.67× |
| Fable 5 / Mythos 5 | $50/MTok | 3.33× |
Multipliers are derived at calculation time as model output price ÷ baseline ($15). Pricing includes margin, so treat multipliers as ±factor-of-2. Verified against the live Anthropic models documentation on 2026-06-12. Directional accuracy (Haiku < Sonnet < Opus < Fable) holds; absolute magnitudes carry the ±50% uncertainty. Models not in the table fall back to the Sonnet baseline (1.00×).
ML.ENERGY Leaderboard v3.0 (Dec 2025): Llama 3.1 70B FP8 on 8×H100 = 0.39 J/output token (GPU, measured via NVML). Apply 1.82× server overhead (GPU ≈ 55% of DGX H100 TDP) → 0.71 J/token at IT load. At US average WUE (1.8 L/kWh): 0.71 ÷ 3,600,000 × 1800 = 0.00036 mL/token (mid rate). Llama 70B is used as the closest publicly-measured proxy for Claude Sonnet — Anthropic does not disclose its hardware or energy use.
Prior anchor (Li et al. 2023, GPT-3 era): 0.014 mL/token — 39× higher. The paper's lead author confirmed (2026-05-31) those estimates should not be applied to modern models. See methodology.md for the full correspondence.
The pricing proxy gives ~0.02× ($0.30/$15 MTok). At that weight, cache reads dominate long-context Claude Code sessions. The 0.001 floor prevents dominance while acknowledging that some compute is involved. A v2 formula will introduce a cache_size × output_tokens cross-term. The deviation from the pricing proxy is documented in formula.json and absorbed by the ±50% accuracy band.
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