Grok 4.5 vs Claude Opus 4.8: Which Model Should You Use in 2026?

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Grok 4.5 is the better choice on price and throughput. Claude Opus 4.8 holds the edge on deep reasoning and agentic reliability. For most developers who need fast, cost-efficient completions at scale, Grok 4.5 is hard to beat at $2/$6 per million tokens. For complex multi-step tasks and coding agents, Opus 4.8 earns its $5/$25 premium.

  • Grok 4.5: $2/$6 per million tokens (input/output), ~90 tokens/sec, 500K context
  • Claude Opus 4.8: $5/$25 per million tokens, strong on reasoning benchmarks, 200K context
  • Grok 4.5 claims 4x better reasoning efficiency vs Opus while costing less than half the price

What is Grok 4.5?

Grok 4.5 is xAI's latest frontier model, announced in mid-2026. It targets the upper tier of reasoning models but with notably aggressive pricing. The model supports up to 500K context tokens, with standard pricing doubling above 200K tokens ($4/$12 for long context). At ~90 tokens/sec, it's meaningfully faster than most competitors at this capability tier.

One detail worth noting from Cursor's integration post: xAI trained Grok 4.5 in part using data from Cursor's coding sessions. That likely explains its strong performance on code generation and completion tasks.

What is Claude Opus 4.8?

Claude Opus 4.8 is Anthropic's most capable model as of mid-2026. It's positioned as the top reasoning and agentic model in Anthropic's lineup, succeeding Opus 4.5 and 4.6. Opus 4.8 is priced at $5 input / $25 output per million tokens, with a 200K context window.

Opus 4.8 is the engine behind Claude Code and is well-suited for long agentic tasks, multi-step code generation, and contexts where reliability over many sequential steps matters more than raw speed.

Grok 4.5 vs Claude Opus 4.8: head-to-head comparison

AttributeGrok 4.5Claude Opus 4.8
Input price (per M tokens)$2 (standard), $4 (200K+)$5
Output price (per M tokens)$6 (standard), $12 (200K+)$25
Context window500K tokens200K tokens
Speed (tokens/sec)~90Moderate
Reasoning tierNear Opus 4.7 level (lower tier)Top of Anthropic lineup
Best forHigh-volume, cost-sensitive, fast completionsDeep agentic tasks, Claude Code
Coding training dataIncludes Cursor session dataGeneral corpus

How do they compare on reasoning and coding?

According to early community benchmarks and HN discussion, Grok 4.5 benchmarks around the Opus 4.7 level, placing it at the lower end of the top tier alongside models like GLM 5.2. It isn't clearly better than Opus 4.8 on pure reasoning, but it gets very close at a fraction of the output cost.

On coding specifically, Grok 4.5 benefits from Cursor's training data, which gives it an edge on practical code completion patterns. Opus 4.8 counters with better multi-step agentic reliability: fewer dropped instructions across long context, better tool use, and tighter integration with Anthropic's tooling like Claude Code.

If you're comparing them inside a coding assistant like Cursor, early reports suggest Grok 4.5 is competitive, especially on shorter tasks. For Claude Code users, Opus 4.8 remains the backbone model — and if you're hitting usage limits, tools like Usagebar help track your 5-hour session windows and weekly caps so you don't get caught off guard.

Which is better for API use and high-volume workloads?

On pure economics, Grok 4.5 wins by a wide margin. Output costs are $6/M vs $25/M for Opus 4.8. For applications generating millions of tokens, that's a 4x cost difference. Combined with faster throughput (~90 t/s vs typical mid-50s for frontier models), Grok 4.5 delivers more tokens per dollar per second.

For comparison: GPT-5.5 is $5/$30, GPT-5.6 is $5/$30, and Opus 4.8 is $5/$25. Grok 4.5 undercuts all of them on output price. The caveat is long-context work over 200K tokens, where pricing doubles. If you're regularly working near 200K+ tokens, the gap narrows.

Which should you use for AI-assisted coding?

It depends on your workflow:

  • Use Grok 4.5 if you're building API-first applications, need fast completions, or are cost-sensitive and working mostly within 200K tokens. It's a strong choice in Cursor for everyday coding tasks.
  • Use Claude Opus 4.8 if you rely on Claude Code for agentic workflows, long multi-step tasks, or need Anthropic's tool integration. The reliability advantage compounds in long sessions.
  • Use both depending on task type. Grok 4.5 for fast drafts and straightforward completions, Opus 4.8 for architecture review, complex debugging, and anything requiring sustained multi-step reasoning.

If you use Claude Code regularly, you're likely hitting Opus 4.8 usage limits. See our guides on checking Claude Opus usage limits and how Claude Code compares to Cursor on pricing.

Key takeaways

  1. Grok 4.5 is priced at $2/$6 per M tokens, roughly 4x cheaper on output than Opus 4.8 ($5/$25).
  2. Grok 4.5 runs at ~90 tokens/sec and supports 500K context (with price doubling above 200K).
  3. Reasoning quality is close: Grok 4.5 benchmarks near Opus 4.7 level, Opus 4.8 is a step above.
  4. For Claude Code users, Opus 4.8 remains the recommended model. Grok 4.5 is the better pick for pure API throughput and cost-sensitive apps.
  5. Both models are "frontier tier." The choice is ultimately about trade-offs in cost, speed, and workflow fit.

Sources

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