Head-to-head
Grok 4.3 vs Claude Opus 4.8: which AI model wins in 2026?
Grok 4.3 ($2.50/1M out) and Claude Opus 4.8 ($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 Grok 4.3. On budget, Grok 4.3 wins: it starts at $2.50/1M out versus $25/1M out for Claude Opus 4.8.
Line-by-line comparison
Strengths and weaknesses
Grok 4.3
- Aggressive pricing: $1.25/$2.50 per 1M tokens, 58% cheaper input and 83% cheaper output than Grok 4, undercutting GPT-5.5 and Gemini 3.1 Pro
- Major agentic leap: +321 Elo on GDPval-AA versus Grok 4.20, with strong tool calling and instruction following
- Cached input at $0.20/1M (84% discount), a big saver for repeated agent loops
- Configurable reasoning effort (none/low/medium/high) in one model at one price, no routing between fast and deep variants
- Praised on HN for natural, concise tone and token-dense outputs that lower real-world costs
- Solid throughput around 130 output tokens/sec (Artificial Analysis)
- Coding reasoning judged 'not competitive with the big April releases' by HN developers; intelligence frontier barely moved since Grok 4
- Non-hallucination score dropped 8 points vs Grok 4.20 on AA-Omniscience; 4.20 remains xAI's safer pick for precision-critical domains
- High time to first token (~13s at high reasoning effort per Artificial Analysis), painful for interactive apps
- Context window shrank to 1M from Grok 4.20's 2M
- Recurring trust and safety complaints (harmful content reports, inconsistent behavior) and no MCP/connected-apps support in the consumer app
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)
Cast your verdict
One recommendation per tool per gladiator. It reshapes the crowd score everyone sees.
The arena’s verdict on Grok 4.3
Pick Grok 4.3 if you run agentic or high-volume pipelines where cost per call dominates: it delivers near-frontier reasoning and a big tool-calling jump over Grok 4.20 at a fraction of GPT-5.5 or Gemini 3.1 Pro pricing. Skip it if coding precision is your priority, as developers still rank Claude and the big April releases ahead. Also stay on Grok 4.20 if you need its 2M context or its better non-hallucination score for legal, medical, or compliance work. Latency-sensitive apps should test the ~13s time to first token before committing.
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.
What the crowd says
On Grok 4.3
No verdicts yet. Be the first to speak.
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.”
Keep comparing
Frequently asked questions
Is Grok 4.3 better than Claude Opus 4.8?
The crowd currently sides with Claude Opus 4.8: 57% recommend it, versus 50% for Grok 4.3 (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, Grok 4.3 or Claude Opus 4.8?
Grok 4.3 is cheaper: it starts at $2.50/1M out, while Claude Opus 4.8 starts at $25/1M out.
How much do Grok 4.3 and Claude Opus 4.8 cost per 1M tokens?
Grok 4.3: $1.25/1M in per 1M input tokens, $2.50/1M out per 1M output tokens. Claude Opus 4.8: $5/1M in per 1M input tokens, $25/1M out per 1M output tokens.