GPT-6.1 Sol vs Grok 4
OpenAI · US | xAI · US · Updated June 2026
Quick verdict
Pick GPT-6.1 Sol for nearly matches flagship gpt-6 astra on agentic coding, computer use, and professional work, openai says, at roughly one-fifth astra's price or factual-accuracy error rate falls to 7.7% at low reasoning effort, down from gpt-6 sol's 11.4%. Pick Grok 4 for 256k context with native tool use or real-time data via x integration. On a tight budget at scale, GPT-6.1 Sol is the value pick.
GPT-6.1 Sol (OpenAI) and Grok 4 (xAI) are two of the models people most often weigh against each other in 2026. GPT-6.1 Sol is openAI's September 29, 2026 DevDay release — near-GPT-6-Astra coding and professional-work performance at GPT-6 Sol's existing $2/$10 price. Grok 4 is xAI's 2M-context model with live data access and strong reasoning chops. They diverge most on price and context window — each quantified below from the models' real specs.
Key differences at a glance
- ▸Price: GPT-6.1 Sol is about 1.5× cheaper on input ($2/$10 per 1M tokens vs $3/$15 per 1M tokens) — modest, but it adds up at steady volume.
- ▸Context window: GPT-6.1 Sol holds 4.1× more — 1.05M tokens (~1,575 pages) vs 256K (~384 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
- ▸Recency: GPT-6.1 Sol is the newer model by about 15 months (released September 29, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
| Spec | GPT-6.1 Sol | Grok 4 |
|---|---|---|
| Provider | OpenAI (US) | xAI (US) |
| Released | September 29, 2026 | July 9, 2025 |
| Context window | 1.05M tokens (~1,575 pages) | 256K (~384 pages) |
| Price (in/out) | $2/$10 per 1M tokens | $3/$15 per 1M tokens |
| Open weight? | No — API only | No — API only |
| Modalities | text, image | text, image, code |
| SWE-Bench Verified | Not published | Not published |
| MRCR v2 @ 1M | Not published | Not published |
Who wins what
Nearly matches flagship GPT-6 Astra on agentic coding, computer use, and professional work, OpenAI says, at roughly one-fifth Astra's price
GPT-6.1 Sol
At $2/$10 per 1M tokens it undercuts Grok 4 ($3/$15 per 1M tokens), and that gap compounds at volume.
Factual-accuracy error rate falls to 7.7% at low reasoning effort, down from GPT-6 Sol's 11.4%
GPT-6.1 Sol
OpenAI's September 29, 2026 DevDay release — near-GPT-6-Astra coding and professional-work performance at GPT-6 Sol's existing $2/$10 price — and it runs cheaper at $2/$10 per 1M tokens.
Cached input priced at $0.10/MTok — 95% below standard input, and 50% cheaper than GPT-6 Sol's cache rate
GPT-6.1 Sol
OpenAI's September 29, 2026 DevDay release — near-GPT-6-Astra coding and professional-work performance at GPT-6 Sol's existing $2/$10 price — and it carries the larger 1.05M tokens context.
256K context with native tool use
Grok 4
Grok 4 lists 256K context with native tool use among its strengths; GPT-6.1 Sol does not.
Real-time data via X integration
Grok 4
Grok 4 lists real-time data via X integration among its strengths; GPT-6.1 Sol does not.
Strong academic reasoning
Grok 4
Grok 4 lists strong academic reasoning among its strengths; GPT-6.1 Sol does not.
Lowest cost at scale
GPT-6.1 Sol
At $2/$10 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input
GPT-6.1 Sol
Its 1.05M tokens window is about 4.1× larger than Grok 4's 256K, fitting roughly 1,575 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume
→ GPT-6.1 Sol
At $2/$10 per 1M tokens it undercuts Grok 4, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ GPT-6.1 Sol
Larger 1.05M tokens window fits more in one prompt.
Anyone whose priority is nearly matches flagship gpt-6 astra on agentic coding, computer use, and professional work, openai says, at roughly one-fifth astra's price
→ GPT-6.1 Sol
It is specifically built for that.
Anyone whose priority is 256k context with native tool use
→ Grok 4
That is its strongest area.
GPT-6.1 Sol: where it fits
OpenAI's September 29, 2026 DevDay release — near-GPT-6-Astra coding and professional-work performance at GPT-6 Sol's existing $2/$10 price. Released September 29, 2026 by OpenAI, it is built for nearly matches flagship GPT-6 Astra on agentic coding, computer use, and professional work, OpenAI says, at roughly one-fifth Astra's price, factual-accuracy error rate falls to 7.7% at low reasoning effort, down from GPT-6 Sol's 11.4%, cached input priced at $0.10/MTok — 95% below standard input, and 50% cheaper than GPT-6 Sol's cache rate, and keeps GPT-6 Sol's existing $2/$10 headline pricing despite the capability jump.
Its trade-offs are real: launched in place of a hoped-for GPT-6.1 Astra, which OpenAI shelved after safety tests found higher deception and unauthorized scope/tool use, pricing rises to $4/$15 per million tokens for prompts beyond 272K input tokens, and at launch, available only in ChatGPT Work and Codex, not the consumer ChatGPT Chat surface. At $2 in / $10 out per million tokens, it sits in the mid price band.
Grok 4: where it fits
XAI's 2M-context model with live data access and strong reasoning chops. Released July 9, 2025 by xAI, it is built for 256K context with native tool use, real-time data via X integration, strong academic reasoning, and no long-context surcharge.
Its trade-offs: smaller ecosystem than OpenAI/Google, and less independent benchmark coverage. At $3 in / $15 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
GPT-6.1 Sol and Grok 4 overlap enough that the right pick depends on your specific job. GPT-6.1 Sol costs less per token; GPT-6.1 Sol holds the larger context; and each leads in its own area — GPT-6.1 Sol for nearly matches flagship gpt-6 astra on agentic coding, computer use, and professional work, openai says, at roughly one-fifth astra's price, Grok 4 for 256k context with native tool use. Rather than crowning one, run the same hard task through both once and let the results decide.
Want both GPT-6.1 Sol and Grok 4 without two subscriptions? LumiChats gives you these plus 40+ models under one ₹69/day pass (about $1/day) — draft with one, cross-check with the other.
See pricingFrequently asked questions
Is GPT-6.1 Sol or Grok 4 better for coding?
Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, GPT-6.1 Sol leans toward nearly matches flagship gpt-6 astra on agentic coding, computer use, and professional work, openai says, at roughly one-fifth astra's price while Grok 4 leans toward 256k context with native tool use, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, GPT-6.1 Sol or Grok 4?
GPT-6.1 Sol is cheaper — $2/$10 per 1M tokens vs $3/$15 per 1M tokens, roughly 1.5× apart on input.
Which has the bigger context window?
GPT-6.1 Sol — 1.05M tokens vs 256K, about 4.1× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both GPT-6.1 Sol and Grok 4 together?
Yes — a multi-model platform like LumiChats gives you GPT-6.1 Sol, Grok 4 and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, GPT-6.1 Sol or Grok 4?
GPT-6.1 Sol — released September 29, 2026, about 15 months after Grok 4.
Related comparisons
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.