ROUTING DECISION — 21 DAYS UNTIL SONNET 5 PRICE CHANGE
● Sonnet 5 price now: $2/$10/M (through Aug 31)
● Sonnet 5 price from Sept 1: $3/$15/M — 50% increase + tokenizer adds 10-35% more tokens on code
● Opus 5 price: $5/$25/M — stable, no announced change
● Current price gap: Sonnet 5 2.5× cheaper on input vs Opus 5
● Post-Aug-31 gap: Sonnet 5 1.67× cheaper on input vs Opus 5
● Intelligence gap: Opus 5 higher — AA Index 61, ARC-AGI-3 30.2%, effort dial
● August 31 action: Front-load batch work on Sonnet 5 before the price step-up
The routing decision between Sonnet 5 and Opus 5 is both a capability question and a timing question. On capability: Sonnet 5 is Anthropic's best model for writing quality and general tasks at a lower intelligence ceiling. Opus 5 is the highest-intelligence model available from Anthropic — AA Index 61, ARC-AGI-3 30.2%, effort dial for cost control. On timing: Sonnet 5 is currently at introductory pricing ($2/M) that expires August 31. Any team running batch workloads that are appropriate for Sonnet 5 should front-load that work before September 1.
Route to Sonnet 5 (and front-load before Aug 31):
Writing · summarisation · instruction following · content generation · code review at volume · most RAG applications · anything where Sonnet 5's quality is sufficient. Currently $2/M — the most cost-effective high-quality model available until September 1.
Route to Opus 5:
Hard reasoning tasks · complex multi-step planning · ARC-AGI-3 style abstract problems · tasks where the effort dial (trade cost for capability per request) is useful · any task where Sonnet 5 demonstrably fails on quality. $5/M — use only when Opus 5's intelligence ceiling is necessary.
Do before August 31: Run batch jobs on Sonnet 5. Enable prompt caching on stable system prompts (up to 90% savings). Audit which current Opus 5 requests can be routed to Sonnet 5 — at $2 vs $5/M, the cost difference compounds fast at volume.
Last updated August 10, 2026. Related: Sonnet 5 August 31 deadline action plan → · Sonnet 5 vs Haiku 4.5 routing →