Anthropic Claude Fable 5.2 vs Anthropic Claude Sonnet 5.5 — API Pricing, 150K Cache & Latency Benchmark
Side-by-side unit economics audit comparing Anthropic Claude Fable 5.2 (anthropic/claude-fable-5-2: Input $8/1M, Output $40/1M, Warm Cache Read $0.2/1M) against Anthropic Claude Sonnet 5.5 (anthropic/claude-sonnet-5-5: Input $2/1M, Output $10/1M, Warm Cache Read $0.1/1M).
Activate 4-breakpoint prefix caching on Anthropic Claude Fable 5.2 to cut input token costs from $8/1M down to $0.2/1M, or route async workloads via Batch API for 50% off.
Lock static system prompt prefixes on Anthropic Claude Sonnet 5.5 to pay $0.1/1M warm cache rates instead of $2/1M uncached input, plus eligible startup cloud credits.
In Etuki FinOps telemetry comparing Anthropic Claude Fable 5.2 (API ID: anthropic/claude-fable-5-2) vs Anthropic Claude Sonnet 5.5 (API ID: anthropic/claude-sonnet-5-5), Anthropic Claude Sonnet 5.5 offers lower standard uncached input pricing at $2/1M tokens, while Anthropic Claude Sonnet 5.5 leads in 10-turn 150K cache-pinned coding economics at $0.6350 per 10 turns (saving $1.6350 over Anthropic Claude Fable 5.2). For latency-sensitive interactive agents, Anthropic Claude Sonnet 5.5 delivers 150ms faster P90 time-to-first-token (310ms vs 460ms).
| Specification / FinOps Dimension | Anthropic Claude Fable 5.2 (anthropic/claude-fable-5-2) | Anthropic Claude Sonnet 5.5 (anthropic/claude-sonnet-5-5) | Verified Advantage |
|---|---|---|---|
| Official Vendor API ID | anthropic/claude-fable-5-2 | anthropic/claude-sonnet-5-5 | UMCE 563-Registry Locked |
| 563-Registry & Routing Eligibility | is_known: true | routable: true | is_known: true | routable: true | Both Merkle Verified |
| Standard Uncached Input (/1M tokens) | $8 / 1M | $2 / 1M | Anthropic Claude Sonnet 5.5 |
| Warm Prefix Cache Read (/1M tokens) | $0.2 / 1M | $0.1 / 1M | Anthropic Claude Sonnet 5.5 |
| Standard Output (/1M tokens) | $40 / 1M | $10 / 1M | Anthropic Claude Sonnet 5.5 |
| Context Window Capacity | 1000K Tokens | 200K Tokens | Anthropic Claude Fable 5.2 |
| 150K Prompt × 10 Turns (Unpinned Cold + 2K Out) | $12.8000 | $3.2000 | Anthropic Claude Sonnet 5.5 |
| 150K × 10 Turns Case A (100% Static Pinned) | $2.2700 (saves $10.5300) | $0.6350 (saves $2.5650) | Anthropic Claude Sonnet 5.5 (-$1.6350) |
| 150K × 10 Turns Case B (90% Static + 10% Tail) | $3.3230 (saves $9.4770) | $0.8915 (saves $2.3085) | Anthropic Claude Sonnet 5.5 |
| P50 / P90 First-Token Latency | 286ms / 460ms (92 tok/s) | 211ms / 310ms (108 tok/s) | Anthropic Claude Sonnet 5.5 (-150ms) |
1. Full-Turn Rate-Card Substitution for Anthropic Claude Fable 5.2: At an uncached input rate of $8/1M, output rate of $40/1M, and warm cache read rate of $0.2/1M, running 10 consecutive 150,000-token coding agent turns (with 2,000 output tokens/turn) without prefix pinning costs $12.8000. Locking 100% static prefixes (Case A: 1 cold turn + 9 warm cached turns + 20K total output) reduces 10-turn spend to $2.2700 (saving $10.5300); under a 90% static prefix + 10% dynamic tail workload (Case B), 10-turn spend is $3.3230.
2. Full-Turn Rate-Card Substitution for Anthropic Claude Sonnet 5.5 & Winner Verdict: On Anthropic Claude Sonnet 5.5 ($2/1M input, $10/1M output, $0.1/1M warm cache), 10 unpinned 150K turns cost $3.2000, dropping to $0.6350 in Case A and $0.8915 in Case B. Across every 10-turn 150K coding loop (including output tokens), Anthropic Claude Sonnet 5.5 delivers an additional $1.6350 Case-A cost advantage.
Production Workload TCO: 25,000 MAU • 50M Tokens/Mo (50% Cache Hit) • 2,000 GB Egress
💡 Optimal FinOps Verdict: Deploying Anthropic Claude Sonnet 5.5 saves $422.00/month ($5064/year) at 25,000 MAU & 50M monthly tokens (80% input / 20% output split with 50% prefix cache hit rate).