Grok 4.6 vs Grok 4.5: What Changed and Should You Upgrade?

Grok 4.6 arrived on August 12, 2026, just 35 days after Grok 4.5. Short gaps usually mean incremental change, and that is broadly what happened — but the changes are not uniformly improvements, and a couple of them will cost you money if you do not notice.

What stayed the same?

More than you might expect for a version bump:

• Context window: 500,000 tokens, unchanged
• Headline pricing: $2 per million input, $6 per million output — unchanged
• Modality: text and image in, text out
• Regions: us-east-1 and us-west-2 only, still no EU

xAI disclosed no architecture details for either model, so whether 4.6 is a new base model or 4.5 with extended post-training is unknown. Claims either way are speculation.

What actually improved?

SWE-bench, substantially

The strongest verified result in the release. Vals AI measures Grok 4.6 at 95.60% on SWE-bench, roughly nine points above Grok 4.5. That is a real gain on a benchmark that matters for practical software work.

Reasoning and general intelligence

Grok 4.6 scores 60.92 on the Artificial Analysis Intelligence Index (xAI claimed 61, which checks out). That moves it to 4th overall, effectively tied with GPT-5.6 Sol Max and behind Claude Opus 5 and Fable 5.

A new reasoning level

Grok 4.6 adds xhigh to the reasoning_effort options. Grok 4.5 accepted the parameter but silently downgraded it to high, so this is the first release where the setting does anything.

Non-agentic coding

LiveBench's coding score rose by more than six points. For single-shot code generation — write this function, fix this bug, explain this file — 4.6 is meaningfully better.

What got worse?

This is the part that gets skipped in most upgrade write-ups.

Agentic coding regressed

Both moved the wrong way, and the SkillsBench drop is large — Grok 4.5 ranked first on that board. Because non-agentic coding rose over the same period, this is a specific regression in multi-step tool-using work rather than general degradation.

It also sits awkwardly next to xAI's own launch framing about a focus on long-running agents. If you use Grok inside an agent loop, benchmark your own workload before upgrading rather than assuming a newer version is better.

Latency got much worse

Time to first token went from 8.7 seconds on Grok 4.5 to 31.2 seconds on 4.6 — more than three times longer. Throughput is about 65.5 tokens per second, 17th of 20 models measured. For interactive tooling, a half-minute wait before the first token is a genuine usability problem.

Cost per job went up, even though the price did not

Two compounding causes: Grok 4.6 emits roughly 47% more output tokens for the same work, and cached input costs 67% more. The result is a 2.32x increase in measured cost per task on identical benchmarks despite an unchanged rate card.

The cache rise hits agent loops hardest, because every turn re-sends the accumulated conversation. And note the threshold that applies to both versions: any prompt of 200K tokens or more bills the entire request at $4/$12, not just the tokens above the line.

Should you upgrade?

Yes, if your workload is one-shot or few-shot coding. SWE-bench up nine points and LiveBench coding up six is a clear win, and the extra output tokens matter less on short tasks.

Yes, if you were already reaching for xhigh and getting high silently.

Test first, if you run long agent loops. Agentic coding and SkillsBench both regressed, output tokens are up 47%, and the cache price rose — three effects that all compound in exactly that workload.

Probably not, if latency is user-visible. Going from 8.7 to 31.2 seconds before the first token will be felt.

Reconsider the vendor entirely, if you are choosing purely on cost. Meta's Muse Spark 1.2, launched a week earlier, is about half the cost per task with twice the context and is statistically tied with Grok 4.6 on the Vals Index.

The honest summary

Grok 4.6 is a sideways-and-slightly-up release. It is better at writing code and reasoning, worse at agentic loops and latency, and more expensive to run despite an unchanged price list.

The most useful way to think about it comes from developers who have actually run it: Grok 4.6 is roughly Claude Opus 4.8-class at about a third of the price, and the workflow people keep reporting is to plan with an expensive model and implement with Grok. That is a real and valuable role. It is just not the same as a frontier upgrade.

FAQ

Is Grok 4.6 better than Grok 4.5?

For coding and reasoning, yes — SWE-bench rose about nine points to 95.60% and LiveBench coding by over six. For agentic work, no: LiveBench agentic coding fell from 56.5 to 54.2 and SkillsBench from 66.03 to 55.77.

Did Grok 4.6 change price?

The headline rate is identical at $2/$6 per million tokens. But cached input rose from $0.30 to $0.50, and measured cost per task rose from $0.360 to $0.837 because Grok 4.6 produces about 47% more output tokens.

Is Grok 4.6's context window bigger?

No. Both are 500,000 tokens, which is the smallest of the current frontier models. Prompts of 200K or more bill the entire request at the doubled $4/$12 rate.

Is Grok 4.6 slower than Grok 4.5?

Yes, noticeably. Time to first token went from 8.7 seconds to 31.2 seconds, and throughput is around 65.5 tokens per second.

What is xhigh reasoning effort?

A new reasoning level in Grok 4.6. Grok 4.5 accepted the parameter but silently downgraded it to high, so 4.6 is the first version where it has an effect.

Should I upgrade my agent from Grok 4.5 to 4.6?

Benchmark first. Agentic coding regressed, output tokens rose 47%, and cached input costs 67% more — three effects that compound in agent loops specifically.