Head-to-head
Claude Opus 4.8 vs Claude Opus 4.6: which AI model wins in 2026?
Claude Opus 4.8 ($25/1M out) and Claude Opus 4.6 ($25/1M out) are two of the most-used AI models in 2026. Across 3 community votes, Claude Opus 4.8 leads with 57% approval.
Quick verdict
On Reasoning, pick Claude Opus 4.8: the arena rates it 4.5/5 against 4/5 for Claude Opus 4.6. Both start at the same price: $25/1M out.
Line-by-line comparison
Strengths and weaknesses
Claude Opus 4.8
- SWE-Bench Pro 69.2% (vs 64.3% for Opus 4.7) and beats prior Opus models on CursorBench at every effort level; strong real-world reports on large refactors and multi-file bug hunts
- About 4x less likely than Opus 4.7 to let flaws in its own generated code pass unflagged; big jump on math reasoning (USAMO 2026: 96.7% vs 69.3%)
- 1M-token context and 128K output at unchanged $5/$25 pricing, with no long-context premium; batch API at 50% off ($2.50/$12.50)
- Fast mode (research preview) delivers up to 2.5x output speed at $10/$50, 3x cheaper than Opus 4.7's fast tier ($30/$150)
- Unique API features for agents: mid-conversation system messages that preserve the prompt cache, and Dynamic Workflows spawning parallel subagents in Claude Code
- 84% on Online-Mind2Web browser automation and record score on Legal Agent Benchmark (first model past 10% all-pass); strong enterprise knowledge work (Box reports 87% vs 77% internally)
- Turn-by-turn regressions reported: missed obvious instructions in planning docs, answering a narrow slice of the goal, and worse one-shot simple UI generation than 4.7
- Writing style criticized by heavy users: excessive hedging, over-cautious editing that 'cuts anything bold or funny' (Steve Yegge), and pushback loops even against well-evidenced theses
- Language-mixing quirk: users report random Chinese, Cyrillic, or Greek insertions in long research threads
- Visible quality degradation past ~200K tokens in hands-on use despite the advertised 1M window
- Vending-Bench regression: fell for scam suppliers about 30x more than 4.7 and negotiates worse (a side effect of stricter honesty alignment)
Claude Opus 4.6
- 80.8% SWE-bench Verified (25-trial average) and top Terminal-Bench 2.0 score at launch, the leading agentic coding model of its generation (Feb 2026)
- First Opus with a 1M-token context window: 76% on MRCR v2 8-needle at 1M tokens vs 18.5% for Sonnet 4.5
- Large reasoning jump over Opus 4.5: ARC-AGI-2 68.8% vs 37.6%, +190 Elo on GDPval-AA economic-value tasks (~144 Elo over GPT-5.2)
- Kept Opus 4.5 pricing ($5/$25 per 1M tokens) despite the gains; full 1M context now billed at standard rates, 50% batch discount
- Adaptive thinking plus effort parameter (low/medium/high/max) to trade intelligence, latency and cost per request
- Strong autonomous agent behavior: parallelizes work and needs less handholding than Opus 4.5 (Every.to Vibe Check)
- Slower and more verbose than Opus 4.5; reviewers report the pace 'wavers under load' on long agentic runs (Every.to)
- Writing regressed: in blind tests Every.to's team preferred Opus 4.5's prose, and 4.6 shows more AI-isms like 'X not Y' constructions
- Sometimes makes unexpected changes and 'doesn't always know its own skills', requiring closer supervision than GPT-5.x Codex per reviewers
- Superseded within months by Opus 4.7 and 4.8 at the same $5/$25 price, and fast mode is not available on 4.6 since June 2026 (requests run at standard speed)
- Some devs report benchmark fatigue: day-to-day coding gains over 4.5 are harder to feel than the scores suggest, and SWE-bench itself was flat vs 4.5 (80.8% vs 80.9%)
Cast your verdict
One recommendation per tool per gladiator. It reshapes the crowd score everyone sees.
The arena’s verdict on Claude Opus 4.8
A drop-in upgrade for Opus 4.7 users: identical API surface and $5/$25 pricing with real gains on long-horizon agentic coding, code review, and enterprise analysis. Choose it if you run Claude Code, multi-file migrations, security audits, or agent pipelines that inspect, act, and verify over many steps. Skip it for quick one-shot UI snippets or prompts tightly tuned to 4.7 behavior, where users report regressions, and pick Sonnet 5 ($3/$15, intro $2/$10 through Aug 2026) if cost matters more than ceiling capability. Writers sensitive to hedging and over-cautious editing may find its style frustrating.
The arena’s verdict on Claude Opus 4.6
A clear upgrade over Opus 4.5 for agentic coding and long-context work at identical pricing, and it held the top agentic coding benchmarks at launch. In mid-2026 however there is little reason to start new projects on it: Opus 4.8 costs the same $5/$25 and outperforms it across the board, so pick 4.6 mainly to pin an already-validated behavior. Writers should avoid it, since blind tests preferred Opus 4.5's prose, and latency-sensitive users should note it is slower than 4.5 with no fast mode option.
What the crowd says
On Claude Opus 4.8
“Writing took a hit. It hedges everything and edits any bold or funny line out of my drafts. Also caught it answering a narrow slice of my planning doc and calling it done.”
“Threw USAMO-level math at it for a lark and it just grinds through. 96.7 vs 69 for 4.7 tracks with what I see. Same $5/$25, 1M context, no excuse not to switch.”
“Upgraded from 4.7 for a monorepo refactor and the difference is real. It actually flags its own sketchy code instead of shipping it. Multi-file bug hunts feel way less babysat.”
On Claude Opus 4.6
No verdicts yet. Be the first to speak.
Keep comparing
Frequently asked questions
Is Claude Opus 4.8 better than Claude Opus 4.6?
The crowd currently sides with Claude Opus 4.8: 57% recommend it, versus 50% for Claude Opus 4.6 (3 votes). On Reasoning, Claude Opus 4.8 rates higher (4.5/5 vs 4/5). The right pick depends on your use case. The line-by-line comparison on this page breaks down pricing, key specs and arena ratings.
Which is cheaper, Claude Opus 4.8 or Claude Opus 4.6?
They cost the same to start: both begin at $25/1M out.
How much do Claude Opus 4.8 and Claude Opus 4.6 cost per 1M tokens?
Claude Opus 4.8: $5/1M in per 1M input tokens, $25/1M out per 1M output tokens. Claude Opus 4.6: $5/1M in per 1M input tokens, $25/1M out per 1M output tokens.