Head-to-head
Grok 4.3 vs Claude Opus 4.5: which AI model wins in 2026?
Grok 4.3 ($2.50/1M out) and Claude Opus 4.5 ($25/1M out) are two of the most-used AI models in 2026. Compare them line by line below, then cast your verdict.
Quick verdict
On Reasoning, pick Grok 4.3: the arena rates it 4/5 against 3.5/5 for Claude Opus 4.5. On budget, Grok 4.3 wins: it starts at $2.50/1M out versus $25/1M out for Claude Opus 4.5.
Line-by-line comparison
From
$2.50/1M outFlat $1.25 in / $2.50 out across all reasoning-effort tiers; cached input $0.20/1M. xAI's own pricing page shows no long-context surcharge, but OpenRouter lists tiered higher rates above 200K total tokens.
$25/1M outOfficial Anthropic API list price for claude-opus-4-5 (single tier, no long-context premium; 200K context, 64K max output); same $5/$25 rate as its Opus 4.6-4.8 successors; 50% batch discount and prompt caching apply. Verified against platform.claude.com models overview 2026-07.
Provider
xAI
Anthropic
Context window
1M tokens
200K tokens
Input price
$1.25/1M in
$5/1M in
Output price
$2.50/1M out
$25/1M out
Modalities
text, vision (text output only)
text, vision
Open weights
No
No
Crowd score
50%(0)
50%(0)
Arena ratings (1-5)
Reasoning
4.0
3.5
Coding
3.5
3.5
Writing
4.5
3.5
Speed
3.5
2.5
Value
4.5
2.5
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 4.5
- First model past 80% on SWE-bench Verified (80.9% at launch), beating Gemini 3 Pro and GPT-5.1 on real-world coding
- 66% price cut vs Opus 4.1 ($5/$25 vs $15/$75 per 1M tokens) made Opus-tier viable for production workloads
- 48-76% fewer output tokens than Sonnet 4.5 at matched or better quality, compounding the price cut
- Effort parameter (introduced with this model) lets devs trade reasoning depth for cost and latency per call
- Strong hands-on reports: one-shot complex refactors, caught race conditions other models missed, converged in ~4 agentic iterations vs ~10 for rivals
- +29% on Vending-Bench vs Sonnet 4.5, with fewer dead-ends on long-horizon autonomous tasks
- 200K context window only (64K max output), far behind the 1M of Gemini 3 Pro and later Claude models; users reported selective attention above ~70% context fill
- Gated to $100-200/month Max tiers in Claude apps at launch; Pro subscribers were locked out and heavy users still hit limits (HN called it 'penny-wise and pound-foolish')
- Moderate latency; extended thinking adds cost and delay on simple tasks
- Superseded since early 2026: Opus 4.6/4.7/4.8 cost the same $5/$25 with 1M context and higher benchmarks, leaving 4.5 no price advantage
- Legacy API surface: manual budget_tokens extended thinking rather than the adaptive thinking of newer Claude models
Cast your verdict
One recommendation per tool per gladiator. It reshapes the crowd score everyone sees.
Grok 4.3$2.50/1M out
50%crowd score · 0
Claude Opus 4.5$25/1M out
50%crowd score · 0
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 4.5
Pick Claude Opus 4.5 only if you have a workload already tuned and pinned to this snapshot (claude-opus-4-5-20251101) and need stability. It was a landmark release, the first past 80% on SWE-bench Verified and a 66% price cut over Opus 4.1, but Anthropic now sells Opus 4.6 through 4.8 at the identical $5/$25 rate with a 1M context window and better scores. Anyone starting a new project should choose Opus 4.8 instead, and cost-sensitive users get near-Opus coding from Sonnet 5 at $3/$15 (intro $2/$10 through Aug 2026). Avoid it entirely if your prompts approach the 200K context ceiling.
Keep comparing
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Frequently asked questions
Is Grok 4.3 better than Claude Opus 4.5?
On Reasoning, Grok 4.3 rates higher (4/5 vs 3.5/5). 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 4.5?
Grok 4.3 is cheaper: it starts at $2.50/1M out, while Claude Opus 4.5 starts at $25/1M out.
How much do Grok 4.3 and Claude Opus 4.5 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 4.5: $5/1M in per 1M input tokens, $25/1M out per 1M output tokens.