Geeknewz exclusive buyer guide built from Anthropic's September 28 Claude Sonnet 5.5 announcement and pricing table, cross-checked against the same lab's Opus 5.5 rate card on that page. No invented quotes, partner claims, or token counts beyond what Anthropic publishes.
If you already pay for Claude API or Claude apps, Sonnet 5.5 looks like a boring mid-tier bump until you stare at the numbers. The sticker on the rate card did not move. The bill for a finished job probably will. Anthropic says the model runs more than 30 percent faster than Sonnet 5, costs up to 30 percent less per task because it burns fewer tokens, and on several agentic coding scores sits next to Opus 5.5 while charging half the per-token price. That is a buyer question, not a press-release vibe check.
Below is the Geeknewz cut: what the rate card actually says, sample math you can redo with your own traffic, where the benchmarks do and do not justify skipping Opus, and a plain call on who should migrate this week.
The rate card, side by side
Anthropic prices Sonnet 5.5 the same as Sonnet 5. Opus 5.5 is still double on input and output. Cache reads match; cache writes do not.
| Price per 1M tokens | Sonnet 5.5 | Opus 5.5 | Opus ÷ Sonnet |
|---|---|---|---|
| Input | $2 | $4 | 2.0× |
| Output | $10 | $20 | 2.0× |
| Cache writes | $2.50 | $5 | 2.0× |
| Cache reads | $0.20 | $0.20 | 1.0× |
So if two models finish the same job with the same token mix, Opus costs twice as much. The interesting claim is that Sonnet 5.5 often does not need the same token mix as Sonnet 5. Anthropic's line is "up to 30% less" per task at the same $2/$10 rates. That only works if the newer model finishes with fewer tokens, which is what their effort-vs-cost charts are trying to sell.
Sample bill math (inputs shown)
Take a mid-size coding agent turn: 500,000 input tokens and 100,000 output tokens, no cache. Plug the published rates:
- Sonnet 5.5: (0.5 × $2) + (0.1 × $10) = $1.00 + $1.00 = $2.00
- Opus 5.5: (0.5 × $4) + (0.1 × $20) = $2.00 + $2.00 = $4.00
That is a clean 2× gap before any efficiency story. Now layer Anthropic's own efficiency claim against Sonnet 5. If a Sonnet 5 job used to cost $2.00 in tokens and Sonnet 5.5 finishes the same work at 70 percent of that token spend, your new bill is about $1.40. That is a $0.60 save on a $2 job, or 30 percent, which matches the ceiling in the announcement. Real traffic will land somewhere under that ceiling. Treat 30 percent as a best case from Anthropic's testing, not a guarantee on your repo.
Scale that example up. One thousand of those Sonnet turns: $2,000 on the rate card, or about $1,400 if the 30 percent efficiency holds. The same thousand turns on Opus at identical tokens: $4,000. You are not comparing a free upgrade to a free upgrade. You are deciding whether Opus's judgment edge is worth roughly double the meter when Sonnet 5.5 is already within a few points on several published coding and knowledge-work scores.
Where the scores actually land
Pulled straight from Anthropic's comparison table on the Sonnet 5.5 page:
| Eval | Sonnet 5.5 | Sonnet 5 | Opus 5.5 |
|---|---|---|---|
| Terminal-Bench 4.0 | 70.6% | 10.3% | 66.4% |
| CursorBench 4.0 | 55.5% | 34.1% | 57.8% |
| FrontierCode 1.1 (Main) | 52.1% at Xhigh / 46.2% Max | 42.4% | 54.4% |
| GDPval-AA v2.1 | 1844 | 1449 | 1846 |
| AA-Briefcase v1.1 | 1811 | 1359 | 1822 |
Terminal-Bench is the headline jump: 10.3 percent to 70.6 percent is a 60.3-point swing, and Sonnet 5.5 even sits above Opus 5.5's reported 66.4 percent on that board (Opus figure is at Xhigh effort per Anthropic's footnote). CursorBench is tighter: Sonnet trails Opus by 2.3 points. GDPval is basically a tie, 1844 vs 1846. That pattern is the buyer story. On well-scoped agentic coding and a lot of knowledge work, Sonnet 5.5 is in Opus's neighborhood at half the token price. Anthropic still says Opus remains clearly stronger on complex, open-ended work that needs sustained judgment. Believe both sentences at once.
Speed matters for the feel of a tool. Anthropic claims Sonnet 5.5 generates outputs more than 30 percent faster than Sonnet 5. Defaults differ by surface: Medium effort in Claude apps, High on the Claude Platform. Lower effort cuts tokens and latency for routine work; higher effort spends more for harder passes.
Safeguards that change the migration checklist
Sonnet 5.5 is the first Sonnet to ship with cyber safeguards closer to Opus 5.5, because Anthropic says its cyber capabilities are comparable to Opus 5. Higher-risk cyber requests fall back to Sonnet 5. Biology safeguards match Sonnet 5. It also adds distillation classifiers and expanded preserved thinking so reasoning stays tied to the account that produced it. If you move chats across accounts or flip mid-session in Claude Code, read Anthropic's migration note before you blame the model for a broken context chain.
Availability is broad on day one: Claude Platform model id claude-sonnet-5-5, plus AWS, Google Cloud, and Microsoft Azure, with zero data retention offered like Opus 5.5 and Sonnet 5. Haiku 5.5 is still "coming weeks," so the cheap high-volume lane is not this release.
Geeknewz verdict: who should buy which lane
Default new coding agents, Cursor-style loops, ticket bots, and slide or spreadsheet grunt work to Sonnet 5.5. Keep Opus 5.5 for architecture reviews, ambiguous multi-hour projects, and anything where a wrong confident answer is expensive. If you are still on Sonnet 5 for everyday tasks, the rate card gives you no reason to wait: same $2/$10, better scores, and a credible path to a lower bill if your token-per-task drops. Geeknewz's view: treat Sonnet 5.5 as the new workhorse and Opus as the specialist, then confirm with a one-week A/B on your own traces before you rewrite every routing rule.