Claude Sonnet vs Claude Opus — which Claude do you actually need?
Same family, two jobs. Claude Sonnet is the 2.5× cheaper workhorse ($2 / $10 vs $5 / $25 per 1M) that handles roughly 90% of coding and chat work. Claude Opus is the max-capability model — a few points higher on SWE-bench (88.6 vs 85.2) and the intelligence index, reserved for the hardest reasoning, architecture, and agentic tasks. Choose Sonnet for volume and cost; choose Opus for judgment on the tough cases. Both carry a 1M-token context.
| Category | Winner | Margin |
|---|---|---|
| Agentic coding · SWE-bench Verified | BClaude Opus | Opus 88.6 vs Sonnet 85.2 — a real but narrow edge (llm-stats, Jul 2026) |
| Overall intelligence · AA Intelligence Index | BClaude Opus | Opus 56 vs Sonnet 53 on the composite index (Artificial Analysis v4.1) |
| Hardest reasoning · architecture, novel debugging | BClaude Opus | Opus is the model teams escalate to when Sonnet stalls |
| Everyday throughput · speed on routine work | AClaude Sonnet | Sonnet is the faster, higher-volume default for the 90% case |
| API input cost · per 1M tokens | AClaude Sonnet | $2 vs $5 — Sonnet is 2.5× cheaper on input |
| API output cost · per 1M tokens | AClaude Sonnet | $10 vs $25 — Sonnet is 2.5× cheaper on output |
| Cost efficiency · blended workload | AClaude Sonnet | Same 2.5× ratio on the blended per-1M figure — Sonnet wins on spend |
| Context window · API model | ·Tie | Both carry a 1M-token window at standard pricing |
| Consumer access · Claude plans | AClaude Sonnet | Sonnet 5 is the Free + Pro default; Opus needs Max for real usage |
| Best overall | ·Depends | Sonnet for volume, Opus for the hard cases — most teams run both |
If you want the cheaper workhorse for most work.
- 2.5× cheaper — $2 / $10 per 1M undercuts Opus's $5 / $25 on both input and output
- Default model — Sonnet 5 runs on the Free tier and on Pro ($20/mo), no Max needed
- Coverage — handles roughly 90% of coding and chat tasks at 85.2 on SWE-bench Verified
- Speed — the higher-throughput choice for agents that loop many times
- Same context — carries the full 1M-token window Opus has
If you need maximum capability on the hard cases.
- Top coding — 88.6 on SWE-bench Verified, above Sonnet's 85.2 and most rivals
- Deepest reasoning — the model to escalate to for architecture, novel algorithms, and security review
- Index lead — 56 vs 53 on the Artificial Analysis Intelligence Index
- Fast mode — an optional $10 / $50 fast tier for latency-sensitive agentic runs
- Judgment — pairs well as the reviewer over Sonnet's first-pass drafts
| Aspect | Claude Sonnet | Claude Opus |
|---|---|---|
| API · inputper 1M tokens · from snapshot | $2.00 A wins | $5.00 |
| API · outputper 1M tokens · from snapshot | $10.0 A wins | $25.0 |
| Cached inputPrompt-cache read $/1M · from snapshot | $0.20 A wins | $0.50 |
| Effective API costBlended workload $/1M · from snapshot | $1.28 A wins | $3.41 |
| API context windowMax input tokens · from snapshot | 1M | 1M |
| Real cost / 1M charsTokenizer-adjusted prose — same Anthropic tokenizer both sides | $0.77 A wins | $1.92 |
| Consumer plansWhere each model lives in Claude subscriptions | Free + Pro $20/mo Sonnet 5 is the default model on the Free tier and on Pro ($17/mo billed annually, $20 monthly) A wins | Max $100–200/mo Opus is metered with tight caps on Pro; full usage arrives on Max 5× ($100) and Max 20× ($200) |
| Capability | Claude Sonnet | Claude Opus |
|---|---|---|
| API context window | 1M tokens | 1M tokens |
| Positioning | Balanced workhorse | Frontier / max capability |
| Agentic coding (SWE-bench Verified) | 85.2% | 88.6% |
| Intelligence Index (AA v4.1) | 53 | 56 |
| Relative throughput / speed | ✓ Faster default | ~ Slower, deeper |
| Vision input | ✓ | ✓ |
| Extended thinking | ✓ | ✓ Deeper budget |
| Prompt caching | ✓ $0.20/M read | ✓ $0.50/M read |
| Batch API (50% off) | ✓ $1 / $5 | ✓ $2.50 / $12.50 |
| Fast mode tier | ✗ | ✓ $10 / $50 |
| Tool use / agents | ✓ | ✓ |
| MCP support | ✓ Native | ✓ Native |
| Free-tier availability | ✓ Default model | ✗ Paid plans only |
| Pro plan access | ✓ Default | ~ Tight usage caps |
| Cloud availability | API, Bedrock, Vertex, Foundry | API, Bedrock, Vertex, Foundry |
The numbers, not the spin.
Claude Sonnet
The default Claude — cheap enough to run everywhere, capable enough for roughly 90% of real coding and chat work.
Strengths
- Cost — $2 / $10 per 1M is 2.5× cheaper than Opus on both input and output
- Reach — the default model on the Free tier and on Pro, so no Max subscription is required
- Coding — 85.2 on SWE-bench Verified clears most rivals despite the lower price
- Throughput — faster responses make it the better fit for high-volume agent loops
- Same context — a full 1M-token window, identical to Opus
Weaknesses
- A few points behind Opus on SWE-bench and the intelligence index
- Less reliable on the hardest architecture, novel-algorithm, and security-review tasks
- No dedicated fast-mode price tier
Best for
- High-volume coding agents and CI loops
- Cost-capped startups shipping on the API
- Everyday chat, drafting, and summarisation
- The first pass in a Sonnet-writes / Opus-reviews pipeline
Claude Opus
The escalation model — the highest Claude scores on coding and reasoning, for the cases where being right matters more than the bill.
Strengths
- Top coding — 88.6 on SWE-bench Verified, ahead of Sonnet and most competitors
- Reasoning — leads Sonnet on the Artificial Analysis Intelligence Index (56 vs 53)
- Judgment — the model teams reach for on architecture, hard debugging, and security review
- Fast mode — an optional $10 / $50 tier for latency-sensitive agentic runs
- Same context — a full 1M-token window at standard pricing
Weaknesses
- 2.5× more expensive than Sonnet on every token
- Slower and overkill for routine work — easy to overspend
- Gated behind Max for real consumer usage; Pro caps are tight
- Only a few points ahead of Sonnet on the neutral benchmarks
Best for
- Architecture design and novel-algorithm work
- The hardest debugging and security analysis
- The reviewer step over Sonnet's drafts
- One-off tasks where a wrong answer is expensive
High-volume coding agent in CI
You run an autonomous agent that writes patches and reruns tests hundreds of times a day, where token spend scales with every loop.
Reasoning: Sonnet 5 lands 85.2 on SWE-bench Verified at 2.5× lower cost, so most of the loop runs cheaply and fast. Reserve Opus for the handful of tasks Sonnet can't close on its own. At scale, across thousands of daily calls, the 2.5× cost gap dwarfs the few-point capability gap.
Architecting a new system from scratch
You're designing a distributed system with novel constraints where one wrong structural decision costs weeks of rework.
Reasoning: This is the case Opus is built for — deepest reasoning, the highest SWE-bench and intelligence-index scores, and stronger judgment on open-ended design. The token premium is trivial next to the cost of a bad architecture. Use Opus here.
Cost-capped startup shipping on the API
You're a small team with a fixed monthly API budget and output tokens dominate your bill.
Reasoning: Sonnet is 2.5× cheaper on both input and output, so the same budget buys ~2.5× the volume at 85.2 SWE-bench quality. Route only the genuinely hard requests to Opus. For unit economics, Sonnet is the default.
Two-model write-then-review pipeline
You want Sonnet to draft code fast, then a stronger model to review the risky parts before merge.
Reasoning: The economical pattern is Sonnet as the high-volume author and Opus as the selective reviewer on security-sensitive or complex diffs. Most tokens run on cheap Sonnet; Opus touches only what needs its judgment. Sonnet carries the pipeline.
Claude Pro subscriber deciding what to run
You pay $20/mo for Pro and want the best model your plan gives you without upgrading.
Reasoning: Sonnet 5 is Pro's default and covers almost everything; Opus is available on Pro but with tight caps you'll hit fast on any real session. Unless your work is consistently at the frontier, Sonnet is the practical pick — and burning your limited Opus quota on routine prompts wastes it. Upgrade to Max only once you regularly need heavy Opus and are hitting its Pro ceiling.
Frequently asked.
Common questions about this comparison, with sources where they matter.
Q · 01 Is Claude Sonnet or Opus better? +
Q · 02 Is Opus worth 2.5× the price of Sonnet? +
$5 / $25 per 1M vs Sonnet's $2 / $10, yet the neutral-benchmark gap is a few points, not a tier. For high-volume or routine work, Sonnet gives you far more output per dollar. Pay the Opus premium selectively — architecture, novel algorithms, security review — not by default. Model your own split in the LLM API cost calculator.