Claude Opus 4.6 vs Claude Sonnet 5
Opus 4.6 and Sonnet 5 are both current Anthropic models with 1M-token context windows, 128K max output, and the same text+image+file input modality. The difference is price and target use: Opus 4.6 is priced as the top-tier agent/coding model, Sonnet 5 as the cost-efficient frontier option released later, on 2026-06-30 versus Opus 4.6's 2026-02-04. Both are available on OpenKey with one API key and a flat 3% fee on provider list price.
Spec vs spec
| Spec | Claude Opus 4.6 | Claude Sonnet 5 |
|---|---|---|
| Context window | 1M | 1M |
| Max output | 128K | 128K |
| Input modalities | text, image, file | text, image, file |
| Output modalities | text | text |
| Released | Feb 4, 2026 | Jun 30, 2026 |
| Reasoning | optional | optional |
Pricing
Per 1M tokens. Provider price plus the flat 3% fee — the sum is what you pay.
anthropic/claude-opus-4.6
Input · 1M tokens
$5.00 + 3%$5.15
Output · 1M tokens
$25.00 + 3%$25.75
Cache read · 1M tokens
$0.500 + 3%$0.515
Cache write · 1M tokens
$6.25 + 3%$6.44
FEE — FLAT, EVERY MODEL3%
anthropic/claude-sonnet-5
Input · 1M tokens
$2.00 + 3%$2.06
Output · 1M tokens
$10.00 + 3%$10.30
Cache read · 1M tokens
$0.200 + 3%$0.206
Cache write · 1M tokens
$2.50 + 3%$2.58
FEE — FLAT, EVERY MODEL3%
One workload, priced on both
10M input + 2M output tokens at each model's price, flat 3% fee included.
anthropic/claude-opus-4.6
$103.00
$100.00 provider + 3%
anthropic/claude-sonnet-5Cheaper
$41.20
$40.00 provider + 3%
Pricing math on a real workload
Provider list price: Opus 4.6 runs $5.00/M input and $25.00/M output; Sonnet 5 runs $2.00/M input and $10.00/M output. On OpenKey, that's provider price × 1.03: Opus 4.6 becomes $5.15/M input and $25.75/M output; Sonnet 5 becomes $2.06/M input and $10.30/M output.
For a 10M-input / 2M-output workload, the computed cost is $100.00 with Opus 4.6 versus $40.00 with Sonnet 5 — a 2.5x gap on input pricing (input_price_ratio: 2.5) that holds across the whole job. If you're running this at any real volume, that's the number that decides the model, not the benchmark chart.
Agent and coding benchmarks
Opus 4.6 has design-arena data across 12 categories. In the agents arena it ranks 3rd in mobileapps (elo 1261, 60.5% win rate), 4th in fullstack (elo 1288, 68.6%) and webapps (elo 1266, 60.9%), and 11th in androidnative (elo 1216, 68.8%). In the models arena it ranks 3rd in codecategories (elo 1342, 63.9%) and uicomponent (elo 1350, 64.5%).
Sonnet 5 has no design-arena entries in this dataset, but Artificial Analysis scores it at a 71.5 coding index, 53.4 intelligence index, and 46.7 agentic index. The two benchmark sources aren't directly comparable, so treat this as: Opus 4.6 has proven design-arena rank data, Sonnet 5 has a separate scoring system showing strong coding relative to its own index.
Context and modality
Both models share a 1,000,000-token context window and 128,000-token max output — context_ratio is 1.0, so there's no long-document advantage either way. Both accept text, image, and file inputs and return text only. Both use the Claude tokenizer. If your workload is long-context RAG or document analysis, this comparison comes down entirely to price and reasoning effort, not context capacity.
Reasoning controls
Opus 4.6 supports reasoning efforts max, high, medium, low, with medium as default and supports_max_tokens enabled for reasoning. Sonnet 5 supports one more tier — max, xhigh, high, medium, low — also defaulting to medium. Sonnet 5's extra xhigh tier gives you a finer dial when you need more reasoning depth without jumping straight to max cost. Both expose the same core tool-use parameters (tool_choice, tools, response_format, structured_outputs).
Which model for which job
| Use case | Pick | Why |
|---|---|---|
| High-volume coding assistant | Claude Sonnet 5 | $40.00 vs $100.00 on a 10M-in/2M-out workload — 2.5x cheaper on input tokens |
| Multi-step fullstack agent tasks | Claude Opus 4.6 | Ranks 4th in the fullstack agents category (elo 1288, 68.6% win rate) |
| Mobile app generation agents | Claude Opus 4.6 | Ranks 3rd in mobileapps (elo 1261, 60.5% win rate) |
| Long-document analysis | Claude Sonnet 5 | Identical 1M-token context to Opus 4.6 at less than half the input price |
| Fine-grained reasoning effort tuning | Claude Sonnet 5 | Supports an extra xhigh effort tier beyond Opus 4.6's four levels |
| UI component / codecategories generation | Claude Opus 4.6 | Ranks 3rd in both uicomponent (elo 1350) and codecategories (elo 1342) |
Questions
- How much more does Claude Opus 4.6 cost than Sonnet 5?
- Opus 4.6 is 2.5x more expensive on input tokens ($5.15/M vs $2.06/M on OpenKey) and roughly 2.5x on output ($25.75/M vs $10.30/M). On a 10M-input/2M-output workload, that's $100.00 for Opus 4.6 versus $40.00 for Sonnet 5.
- Do Opus 4.6 and Sonnet 5 have the same context window?
- Yes. Both support a 1,000,000-token context window and a 128,000-token max completion — context_ratio between them is exactly 1.0. Neither has an edge on long-document handling.
- Which model ranks higher on coding benchmarks?
- They're measured on different scales in this data. Opus 4.6 ranks 3rd in codecategories (elo 1342, 63.9% win rate) on design arena. Sonnet 5 has no design-arena entries but scores 71.5 on the Artificial Analysis coding index, so direct comparison isn't possible from this data alone.
- Can I use both models through one API key?
- Yes. Both Claude Opus 4.6 and Claude Sonnet 5 run on OpenKey under one API key, billed at provider list price plus a flat 3% fee — no separate Anthropic account or key needed for either model.