What's new in Claude Sonnet 5
Which summary reads better? Pick one — models revealed after.Both summaries are AI-generated.
Claude Sonnet 5’s new tokenizer can make the same English documents about 1.4x more tokens, with smaller increases for Spanish and Python and little change for Simplified Mandarin. Even if the model is priced below Opus 4.8 while offering similar performance, production cost and context-budget assumptions need to be remeasured on your actual payloads before switching.
Sonnet 5 delivers near-Opus-4.8 quality at lower per-token prices, but ships a new tokenizer that produces ~1.4x more tokens for English, ~1.33x for Spanish, and ~1.28x for Python—so your effective cost per document rises even as the headline rate drops. Re-benchmark your actual token counts before assuming a cost win, and don't reuse old token-based budget or context-window estimates; Mandarin workloads are the exception where costs stay flat.