GPT-6.1 Sol vs GPT-6 Astra: Price, Performance and Which to Use (2026)

Last updated: November 7, 2026. By Veer. Prices and specs checked on November 7, 2026 against OpenAI’s API pricing, the API models page, the GPT-6.1 Sol launch post and ChatGPT Work and Codex pricing docs. Independent scores from Artificial Analysis. This is a researched comparison built from public docs and third-party benchmarks, not a hands-on test.

OpenAI now sells two serious “thinking” models side by side. GPT-6 Astra arrived on September 3, 2026 as the flagship. GPT-6.1 Sol followed on September 29, and OpenAI pitched it with a blunt line: “Near-Astra intelligence for a fifth of the price.” That’s why “is GPT-6.1 Sol better than Astra?” is one of the top searches for either model. The short version is that Sol isn’t better, but for most work the gap is too small to pay five times as much for.

GPT-6.1 Sol vs GPT-6 Astra: the quick answer

Use GPT-6.1 Sol for everyday coding, documents, agents and anything you run often. Use GPT-6 Astra when one hard task matters more than the bill. OpenAI’s own model guide says to start with Astra for “complex reasoning and coding” and to “choose GPT-6.1 Sol to balance intelligence and cost.” Both models share the same context window, output limit and knowledge cutoff, so you’re choosing on price and peak quality, not on features.

Sources: OpenAI API pricing, models page, GPT-6 Astra model page, API changelog, Artificial Analysis. All prices are USD.

How much cheaper is GPT-6.1 Sol than Astra?

Sol’s list price is exactly one-fifth of Astra’s on input and output, and its cached input is one-tenth. That holds across every processing tier OpenAI sells. Batch and Flex halve both models’ prices, and Fast mode doubles them, so the 5x ratio doesn’t move.

Here’s what that means in practice. A job that reads 1 million tokens and writes 200,000 costs about $4 on Sol and $20 on Astra at standard rates. Caching widens the gap. If most of your prompt is a reused system prompt or codebase, Sol’s cached input at $0.10 per million is a tenth of Astra’s $1.00, which matters a lot for agents that resend the same context on every turn.

Source: OpenAI API pricing, checked November 7, 2026. Regional data residency endpoints add 10%.

Independent testing tells the same story. Artificial Analysis says running its full Intelligence Index costs about $1.27 per task with Sol at max effort, against $6.24 per task for Astra at max. Sol used more output tokens to get there (63.7 million vs 54.3 million), but the lower price more than makes up for it.

Is GPT-6.1 Sol better than GPT-6 Astra?

No. Astra is still OpenAI’s most capable model, but Sol gets within a couple of points on most published tests. On Artificial Analysis’ Intelligence Index, Astra at max effort scores 57 and Sol scores 55. When we checked on October 11 the scores were 53 and 52, so the index has been updated since, and Astra still leads.

OpenAI’s own launch numbers are more detailed. They’re vendor results, so read them as claims rather than independent proof:

• Coding: On DeepSWE v1.1, OpenAI says Sol “matches GPT-6 Astra at roughly one-fifth of the cost.”
• Computer use: On OSWorld 2.0, Sol comes “within 2.1 percentage points of Astra’s score at maximum reasoning effort at roughly one-seventh the cost per task.”
• Science: On Terminal-Bench Science 0.1, Astra “still achieves the highest score among the models tested at 68.1%.” Sol costs $5.47 per task there against $23.80 for Astra.
• Factual accuracy: Sol’s error rate stays “within 1.9 percentage points of GPT-6 Astra’s” across reasoning settings, at under a fifth of the cost.

All four claims come from OpenAI’s GPT-6.1 Sol announcement.

The pattern is consistent. On coding and agent work, Sol is close enough that most teams won’t notice the difference. On hard science and research tasks, OpenAI itself says Astra “should be used for the most difficult scientific research tasks.”

GPT-6.1 Sol vs GPT-6 Astra in ChatGPT and Codex

On a ChatGPT subscription, the real cost is your usage allowance, and Astra burns through it roughly three times faster. OpenAI’s Codex and ChatGPT Work pricing doc estimates local messages per five-hour window on Plus at 15 to 160 for GPT-6.1 Sol and 5 to 45 for GPT-6 Astra. Weekly limits may also apply.

Sources: ChatGPT Work and Codex pricing, ChatGPT models guide, GPT-6 Astra announcement.

A few details matter here:

• Sol isn’t in regular Chat. OpenAI’s launch post says it’s in ChatGPT Work and Codex for Plus, Pro, Business, Enterprise and Edu, and “not yet available in Chat.” Free and Go users get GPT-6 Luna in Codex instead.
• Pro removes the five-hour cap. OpenAI says “Pro plans currently have no five-hour limit,” so Astra’s faster burn rate hurts less there. Our ChatGPT Pro $100 vs $200 vs $500 guide covers which tier fits.
• Sol uses a 500K default context in Codex. The models guide says GPT-6.1 Sol defaults to a 500,000-token window in Codex and ChatGPT Work, even though the API allows 1.05 million.

Plus costs $20 a month in the US and £19.99 in the UK through the App Store. If you’re still deciding on a plan, see ChatGPT Go vs Plus.

Which is faster, Sol or Astra?

They’re about the same per task at max effort, and both can be sped up for more money. Artificial Analysis measured 21.7 minutes per Intelligence Index task for Sol and 21.0 minutes for Astra, both at max reasoning. So pick on price and quality, not speed.

If speed is the priority, both models support Ultrafast mode. OpenAI added it for Astra on September 29 and for Sol on October 8. In the API it costs 6x the standard price. In ChatGPT it drains your included usage 8x faster, and among individual plans only Pro $500 gets it.

Developer differences worth knowing

Both models use the Responses API for tools, but Astra is stricter about settings. OpenAI’s changelog notes that GPT-6 Astra doesn’t support the none reasoning effort, custom temperature or top_p, or log probabilities. Sol supports efforts from low up to max, and its launch added Multi-agent (beta) so the model can delegate to subagents in one request.

The safe pattern for most apps is routing. Send everyday traffic to gpt-6.1-sol, and escalate to gpt-6-astra only when a task fails a quality check or you know in advance it’s unusually hard. If you also use Anthropic models, the same logic applies there; see Sonnet 5.5 vs Opus 5.5 and our Sonnet 5.5 vs GPT-6.1 Sol cost comparison.

Verdict: which should you use?

Pick GPT-6.1 Sol if you code, run agents, process documents or pay by the token. It costs a fifth as much, gets roughly three times as many messages on Plus, and trails Astra by only two points on the Intelligence Index.

Pick GPT-6 Astra for the hardest science, research and long end-to-end projects, or when one wrong answer costs more than the tokens. That’s the job OpenAI itself still reserves for it. For coding specifically, our Claude Code vs Codex guide compares how each plan’s limits stretch, and the GPT-5.5 retirement guide explains how OpenAI’s Astra, Sol, Terra and Luna names fit together.

FAQ

Is GPT-6.1 Sol better than GPT-6 Astra?

No. GPT-6 Astra is still OpenAI’s most capable model and scores 57 vs Sol’s 55 on Artificial Analysis’ Intelligence Index at max effort (checked November 7, 2026). Sol gets close on coding and computer use for a fifth of the price, so it’s the better value for most work.

How much does GPT-6.1 Sol cost compared with GPT-6 Astra?

GPT-6.1 Sol costs $2 per million input tokens and $10 per million output tokens. GPT-6 Astra costs $10 and $50. Cached input is $0.10 for Sol and $1.00 for Astra. Prompts over 272K input tokens cost more on both.

Which is better for coding, GPT-6.1 Sol or Astra?

For most coding, Sol. OpenAI says Sol matches Astra on DeepSWE v1.1 at roughly a fifth of the cost, and it’s the recommended GPT-5.5 replacement in Codex on paid plans. Use Astra for unusually hard or long-running engineering tasks.

Can I use GPT-6.1 Sol in regular ChatGPT?

Not in Chat yet. GPT-6.1 Sol is available in ChatGPT Work and Codex on Plus, Pro, Business, Enterprise and Edu plans. On Enterprise and Edu, an admin has to enable it first.

How many GPT-6 Astra messages do I get on ChatGPT Plus?

OpenAI estimates 5 to 45 local GPT-6 Astra messages per five-hour window on Plus in Codex and ChatGPT Work, versus 15 to 160 for GPT-6.1 Sol. Weekly limits may also apply, and Pro plans have no five-hour limit.

Do GPT-6.1 Sol and GPT-6 Astra have the same context window?

Yes. In the API both have a 1.05 million token context window, a 922,000-token maximum input, 128,000 maximum output tokens and an April 30, 2026 knowledge cutoff.

Sources

1. Introducing GPT-6.1 Sol (OpenAI, September 29, 2026): pricing, benchmark claims, availability.
2. GPT-6 Astra: A new generation of intelligence (OpenAI, September 3, 2026).
3. OpenAI API pricing: Standard, Batch, Flex, Fast and Ultrafast rates.
4. OpenAI API models page and GPT-6 Astra model page.
5. OpenAI API changelog: release and Ultrafast dates, Astra migration notes.
6. ChatGPT Work and Codex pricing and models guide.
7. Artificial Analysis: GPT-6.1 Sol and GPT-6 Astra (checked November 7, 2026).