GPT-6.1 vs GPT-6: One New Model, Not a New Generation (2026)

The short answer: GPT-6.1 is not a new generation — it is one model. OpenAI released GPT-6.1 Sol on September 29, 2026 as a point upgrade to GPT-6 Sol inside the existing GPT-6 lineup. The list price is unchanged ($2 input / $10 output per million tokens), measured intelligence jumps from 47.6 to 51.8 on Artificial Analysis' index, cached input halves to $0.10, the knowledge cutoff moves up ten days, the none reasoning effort disappears, and Ultrafast mode plus a multi-agent beta arrive. No GPT-6.1 Astra or Luna exists — against the flagship GPT-6 Astra, the new model lands one point lower at one-fifth the price.

That naming choice trips a lot of searches: people looking for "GPT-6.1 vs GPT-6" are really asking one of two questions — should I switch from GPT-6 Sol to 6.1? or is 6.1 the new flagship? This page answers both. If you want the full Sol-vs-Astra head-to-head with per-task costs and benchmarks, it has its own comparison.

The GPT-6 lineup after the 6.1 release

Astra stays the flagship for the hardest work, GPT-6.1 Sol becomes the default for complex work at a sane price, GPT-6 Sol remains listed while accounts migrate, and Luna holds the volume tier that powers ChatGPT's Free and Go plans. OpenAI's own one-line summary of the family: Astra for the most demanding work, Sol to "balance intelligence and cost," Luna for cost-sensitive, high-volume jobs.

The upgrade math: GPT-6 Sol → GPT-6.1 Sol

This is the comparison OpenAI documents directly — the docs ship migration guidance for exactly this switch.

Reading it as an upgrade decision:

• Quality per dollar improved on both axes. Intelligence up 4.2 points at the same list price, and the measured cost per benchmark task fell from $1.04 to $0.72 even though the new model writes more tokens — the cached-input halving and higher task success absorb it.
• Raw speed went down. On Artificial Analysis' rig the old GPT-6 Sol outputs 104.6 tokens per second against 62.4 for 6.1 — a real trade-off for latency-sensitive UX, partially offset by 6.1's new Ultrafast tier (6× standard, added October 8) for teams that can pay for speed.
• Cache-heavy workloads save twice. Same list price, but cached input drops from $0.20 to $0.10 per million tokens — agents that re-read the same context on every turn feel this immediately.

Migration checklist for API users

• Point requests at the new snapshot: gpt-6.1-sol replaces gpt-6-sol.
• reasoning_effort: "none" is gone. GPT-6.1 Sol supports low, medium, high, xhigh, and max only. If you shipped GPT-6 Sol at none, re-test at low.
• Chat Completions loses tool calling on this model. GPT-6 Sol allowed function calling with none; GPT-6.1 Sol requires the Responses API for tools and supports Chat Completions only without them.
• Cached input gets cheaper automatically; cache writes stay at $2.50 (1.25× input).
• The knowledge cutoff moved April 20 → April 30, 2026 — rerun evals that probe recent events.
• Prompt-caching behavior and the over-272K surcharge (2× input, 1.5× output) are unchanged.

Versus the GPT-6 flagship: one point, one-fifth of the bill

If "GPT-6" in your search meant Astra, here is the compressed answer: on the same lab's measurements, GPT-6.1 Sol scores 51.8 vs Astra's 52.7 and costs $0.72 vs $3.26 per benchmark task, with identical context windows, cutoffs, and surcharge structures. OpenAI's model-selection ladder still ranks Astra's settings above Sol's, but its deployment guidance recommends 6.1 Sol as the default for complex coding and agentic workflows. The full table with pricing tiers, worked cost examples, and video demos lives in the GPT-6.1 Sol vs GPT-6 Astra comparison.

Where GPT-6 Luna still fits

Luna is untouched by the 6.1 release: $0.10 / $0.50 per million tokens, a 38.1 intelligence score, and it remains the only GPT-6 model on ChatGPT Free and Go. Anthropic's Claude Haiku 5.5 lists at exactly Luna's price — we compared them benchmark-for-benchmark in Haiku 5.5 vs GPT-6 Luna.

Motion graphics: what the 6.1 upgrade changes for that workload

For animation-as-code pipelines — animated SVG/CSS, GSAP timelines, Lottie JSON, Remotion, Manim — the 6.1 upgrade is close to a free quality bump: same $2/$10 rates, +4.2 measured intelligence, cheaper caching for sessions that regenerate repeatedly. The speed drop is the one watch-item for interactive iteration loops; Ultrafast mode is the escape hatch if the lower base rate bothers you. Neither old nor new Sol renders footage — for that you need a video generation model from our tools index.

Why there is no video-length cost comparison here: these models bill by token, and there is no fixed mapping from tokens to seconds of finished animation — a motion-graphics render is generated as code whose length depends on scene complexity, not on playback duration. Per-second pricing only exists where a model actually outputs footage, which is what the video model price database tracks.

Which should you pick?

• On GPT-6 Sol today: migrate, unless you depend on none reasoning effort or Chat Completions tool calling — those are the only regressions, and both have documented workarounds. Same price, better model, cheaper caching.
• Choosing within the family for new work: GPT-6.1 Sol as the workhorse, Luna for high-volume simple jobs, Astra reserved for the steps that fail on Sol.
• Waiting for "GPT-6.2" or a 6.1 flagship: nothing announced — 6.1 exists only as Sol. If you need more than 6.1 Sol, the current answer is Astra, not a bigger 6.1.

FAQ

Is GPT-6.1 a new model generation?

No. GPT-6.1 is a single model — GPT-6.1 Sol, released September 29, 2026 — that upgrades GPT-6 Sol inside the existing GPT-6 lineup. There is no GPT-6.1 Astra or Luna; the flagship remains GPT-6 Astra and the volume model remains GPT-6 Luna.

Should I migrate from GPT-6 Sol to GPT-6.1 Sol?

Yes, for almost everyone: the list price is unchanged at $2/$10 per million tokens, measured intelligence rises from 47.6 to 51.8, and cached input costs half as much. Two things to check first: code that relies on the none reasoning effort will break, and Chat Completions users lose function calling entirely (move tool calls to the Responses API).

Is GPT-6.1 better than GPT-6?

Against the GPT-6 model it replaces (GPT-6 Sol), yes: +4.2 intelligence points on Artificial Analysis' index at the same price. Against the GPT-6 flagship (GPT-6 Astra), GPT-6.1 Sol lands one point lower at one-fifth the token price — a trade most workloads should take.

What did GPT-6.1 change compared to GPT-6 Sol?

Same $2/$10 pricing; cached input halved to $0.10 per million; knowledge cutoff moved from April 20 to April 30, 2026; none reasoning effort removed; Ultrafast mode (6× standard) and a multi-agent beta added. On third-party measurement it is slower than GPT-6 Sol in raw output speed (62.4 vs 104.6 tokens per second).

Is GPT-6.1 Sol available in ChatGPT Free?

No. Per OpenAI, GPT-6.1 Sol, GPT-6 Sol, and GPT-6 Luna are available in ChatGPT Work and Codex, not consumer Chat, and GPT-6.1 Sol is still rolling out account by account. Free and Go plans run GPT-6 Luna.

How much does GPT-6.1 Sol cost?

$2 per million input tokens and $10 per million output tokens — the same as the GPT-6 Sol it replaces, one-fifth of flagship Astra's rates, and 20× Luna's. Cached input is $0.10, cache writes $2.50, and prompts over 272K input tokens bill at 2× input and 1.5× output.

Related comparisons on vidirect

• GPT-6.1 Sol vs GPT-6 Astra — the new balanced model against the flagship, with per-task costs and the full benchmark table.
• Claude Haiku 5.5 vs GPT-6 Luna — the small-model battle at the $0.10/$0.50 price point.
• MiniMax H3 vs Wan 2.2 — generation-over-generation pricing for two current video models.
• Veo 3 vs Veo 3.1 — real output clips from both generations in the Arena.
• Free AI video generators — every current free tier's daily limits, verified against official sources.