Grok 4.5 wins on speed and raw price. Claude Sonnet 5 wins on conciseness, code review, and ecosystem maturity. On agentic and terminal benchmarks Grok 4.5 scores higher; on careful, structured reasoning and availability everywhere, Sonnet 5 is the safer pick. For high-volume coding on a budget, take Grok 4.5. For review-heavy or Claude-ecosystem work, take Sonnet 5. The most efficient setup for coding-heavy users is to run both, with Grok writing and Sonnet reviewing.
Grok 4.5 and Claude Sonnet 5 are both 2026 models, but they were built for different bets. Grok 4.5 launched July 9, 2026, right after a June 28 private beta, with xAI's Elon Musk calling it an "Opus-class" model that runs faster and costs less (The Decoder, July 2026). Claude Sonnet 5 shipped June 30, 2026 from Anthropic as its most agentic Sonnet yet (Anthropic announcement).
The 30-second comparison
Spec | Grok 4.5 | Claude Sonnet 5 |
|---|---|---|
Release date | July 9, 2026 (public) | June 30, 2026 |
Maker | xAI | Anthropic |
Context window | 1M tokens (large) | 1M tokens |
Max output | 128K tokens | 128K tokens |
Knowledge cutoff | mid-2026 (V9 training) | February 28, 2026 |
API price (input / output, per 1M tokens) | $2 / $6 | $2 / $10 intro (to Aug 31), then $3 / $15 |
Output speed | ~80 tokens/sec | fast, no headline figure |
Where to call it | Grok Build, Cursor, xAI console; Word/PPT/Excel plugins | Claude.ai, Anthropic API, Amazon Bedrock, Google Vertex, Azure AI Foundry |
If you only read one row, read the price row, because Sonnet 5's sticker price is not its real price.
Pricing, and the Sonnet 5 catch most pages miss
On paper, both launch-era models are cheap. Grok 4.5 is $2 per million input tokens and $6 per million output tokens (The Decoder). Claude Sonnet 5 is $2 / $10 as an introductory rate through August 31, 2026, then reverts to $3 / $15, the same sticker as Sonnet 4.6 (Anthropic).
The catch: Sonnet 5 ships with a new tokenizer that maps the same text to roughly 42% more tokens for English (about 1.4x English, 1.33x Spanish, and roughly flat for Simplified Mandarin, per Anthropic's release notes). You are billed per token, so an English-heavy workload paying the $2 / $10 rate is effectively paying around $2.84 / $14.20 per million tokens of actual text. That is barely below the old $3 / $15, not the discount the headline implies.
Grok 4.5 has no such token inflation, and xAI also reports it uses about 4.2x fewer tokens than Opus 4.8 on SWE-bench Pro tasks (The Decoder). Lower per-token price plus fewer tokens per task is why Grok 4.5 is the cheapest model in its performance tier by a wide margin.
For context, the current frontier price ladder looks like this (prices via The Decoder, July 2026):
Model | Input / 1M | Output / 1M |
|---|---|---|
Grok 4.5 | $2 | $6 |
Claude Sonnet 5 (intro) | $2 | $10 |
Claude Sonnet 5 (standard) | $3 | $15 |
Claude Opus 4.8 | $5 | $25 |
GPT-5.5 / GPT-5.6 | $5 | $30 |
Claude Fable 5 | $10 | $50 |
For a longer look at Claude pricing across Haiku, Sonnet, and Opus, see the Claude API pricing guide or the Sonnet 5 overview. Grok 4.5 is not yet available through relays at launch (more on that below), so for now the only ways to call it are xAI's own channels.
Benchmarks: where each one wins
Most comparison pages still list Sonnet 5 benchmarks as "not available," because the data is fresh. Here are the numbers that matter, with sources: Grok 4.5 figures from The Decoder, Sonnet 5 figures from Cosmic JS and CodingFleet.
Benchmark | Grok 4.5 | Claude Sonnet 5 | What it tests |
|---|---|---|---|
Terminal Bench 2.1 | 83.3% | 76.1% | Complex command-line / agentic tasks |
SWE-bench Pro | 64.7% | 63.2% | Harder real-world software engineering |
SWE-bench Verified | — | 72.7% | Curated GitHub issue resolution |
DeepSWE 1.1 | 53% | — | Resolving real GitHub issues (vs 67% GPT-5.5, 70% Fable 5) |
Grok 4.5 leads on Terminal Bench 2.1 by a meaningful 7 points, which tracks with its agentic, hands-on-keyboard strength. On SWE-bench Pro the two are effectively tied (64.7 vs 63.2). Where Grok 4.5 trails the frontier is on DeepSWE, where Fable 5 (70%) and GPT-5.5 (67%) sit well above it. If you want the absolute best at multi-step issue resolution, neither Grok 4.5 nor Sonnet 5 is the top model, though Sonnet 5's Verified score (72.7%) is the stronger of these two on curated tasks.
In plain terms: pick Grok 4.5 for terminal-heavy, agentic workflows where speed and cost matter. Pick Sonnet 5 for curated, reviewable code work where you want fewer surprises.
Real-world coding: what developers report
Benchmark tables tell you less than people shipping code every day. Early X feedback from the first 48 hours of Grok 4.5's release is anecdotal, but the pattern is consistent across the first wave of reports.
The dominant finding is that Grok 4.5 writes fast, Opus-quality code for the money, and the smartest users are pairing it with Sonnet 5 rather than choosing between them. @LancerComet2nd runs Grok 4.5 to write and Sonnet 5 to review, calling Grok's quality "genuinely on par with Opus level" with speed as the biggest advantage. @OpulentByte and others flag that Grok 4.5 "beats Sonnet 5 for like 2x cheaper."
The honest caveat is over-engineering. @Rexios85 ran the same prompt through both: Grok 4.5 produced 49 lines of code where Sonnet 5 produced 24 for the same result. If you value minimal diffs and tight code, Sonnet 5 is more disciplined. Grok 4.5 also has a known weak spot on simple, well-specified UI tasks. @Dorizzdt reports it takes several passes on DOM layout work that Claude or Codex finish in one shot, and failed some Bevy tasks outright. New model, rough edges.
Ecosystem and availability
This is where the two models diverge most for a buyer.
Claude Sonnet 5 is everywhere on day one: the Anthropic API, Claude.ai, Amazon Bedrock, Google Cloud Vertex AI, and Azure AI Foundry all carry it, and the surrounding tooling (Claude Code, MCP, prompt caching) is mature. If your stack is already Anthropic-shaped, Sonnet 5 drops in with zero friction.
Grok 4.5 is narrower. At launch it runs through Grok Build, Cursor, and the xAI console, with Word, PowerPoint, and Excel plugins. It is not yet available in the EU (xAI targets mid-July), and it was not callable through API relays on release day: when checked on July 9, the model was provisioned on relays but returned "service temporarily unavailable." For buyers outside the xAI/Cursor orbit, that means waiting. Anthropic also notes in Sonnet 5's system card that it does not push past the Opus-class capability frontier (see how it stacks against the top model in Sonnet 5 vs Opus 4.8), so if you need maximum reasoning, neither Sonnet 5 nor Grok 4.5 replaces Opus.
Which one should you pick
Pick by workflow, not by brand.
High-volume, budget-sensitive agentic coding. Choose Grok 4.5. It is cheaper per token, faster (80 tokens/sec), and ahead on Terminal Bench. Accept the new-model rough edges and the narrower availability.
Code review, structured reasoning, minimal diffs. Choose Claude Sonnet 5. It is more concise, available everywhere, and has the mature Anthropic ecosystem behind it.
Best overall for coding-heavy work. Run both. Grok 4.5 writes the first draft fast and cheap; Sonnet 5 reviews and tightens it. This is what working developers converged on in the first two days, and it plays to each model's strength.
Cheapest way to run Sonnet 5. A relay at 2折 (official × 0.20) brings the intro rate near $0.40 / $2.00 and softens the tokenizer cost. Useful for experimentation and high-volume API work where official SLAs matter less.
If you want maximum frontier reasoning rather than a workhorse coder, step up to Opus 4.8 or Fable 5. Both Grok 4.5 and Sonnet 5 are deliberately the value tier.
FAQ
Is Grok 4.5 better than Claude Sonnet 5 for coding?
It depends on the task. Grok 4.5 scores higher on Terminal Bench 2.1 (83.3% vs 76.1%) and is faster and cheaper, so it wins for high-volume agentic coding. Sonnet 5 is more concise (less over-engineering) and stronger on reviewable, structured work.
Which is cheaper, Grok 4.5 or Claude Sonnet 5?
Grok 4.5 at $2 / $6 per million tokens undercuts Sonnet 5's $2 / $10 intro rate, and Sonnet 5's new tokenizer inflates English text by about 42%, so its effective cost is closer to $2.84 / $14.20. After August 31, 2026, Sonnet 5 reverts to $3 / $15. A relay at 2折 can bring Sonnet 5's effective price back down.
When did Grok 4.5 and Claude Sonnet 5 come out?
Claude Sonnet 5 launched June 30, 2026. Grok 4.5 entered private beta June 28, 2026 and launched publicly on July 9, 2026.
Is Grok 4.5 better for Cursor, and Sonnet 5 better for Claude Code?
Roughly, yes. Grok 4.5 is tightly integrated with Cursor; xAI trained it alongside the editor, so it is the natural fit there. Sonnet 5 is the default-tier model in Claude Code and the broader Anthropic tooling, so it is the natural fit if you live in that ecosystem. Both run fine in general agent frameworks.
Is Grok 4.5 available everywhere?
Not yet. At launch it runs through Grok Build, Cursor, and the xAI console, with EU availability targeted for mid-July. Claude Sonnet 5 is available across the Anthropic API, Claude.ai, Bedrock, Vertex AI, and Azure AI Foundry from day one.
Does Grok 4.5 or Claude Sonnet 5 beat Opus?
No. Anthropic's own system card says Sonnet 5 does not advance past the Opus-class frontier, and Grok 4.5 trails Opus 4.8 and Fable 5 on DeepSWE. Both are positioned as the value tier, not the reasoning frontier. For more on where Sonnet 5 sits in the lineup, see the Sonnet 5 guide and other model comparisons like GLM-5.2 vs Opus 4.6.