GPT-6.1 vs GPT-6: What Changed, Prices, Should You Switch?

GPT-6.1 is an upgrade to GPT-6 Sol, not a new tier. OpenAI announced GPT-6.1 Sol on September 29, 2026 – one week after GPT-6 Sol (September 22). It keeps the same 1.05-million-token context window, 128K max output and $2 / $10 per million input/output tokens, but halves cached input to $0.10 and improves coding, computer use and agent reliability. The one compatibility catch: GPT-6.1 Sol no longer supports reasoning effort none, and tool calling needs the Responses API.

"GPT-6" is a family, so the comparison depends on which GPT-6 you mean. Below: the family at a glance, what actually changed from 6 to 6.1, and when switching is worth it.

The GPT-6 family in one table

Model	Released	Role
GPT-6 Astra	Early September 2026	Flagship, highest price
GPT-6 Sol	September 22, 2026	Cost-effective high-end
GPT-6 Luna	September 22, 2026	Lower-cost tier
GPT-6.1 Sol	September 29, 2026	Upgrade of GPT-6 Sol, same price

So when people search "GPT-6.1 vs GPT-6", the like-for-like comparison is GPT-6.1 Sol vs GPT-6 Sol. If you mean the flagship, see our separate GPT-6.1 Sol vs GPT-6 Astra comparison – Astra costs five times as much.

GPT-6.1 Sol vs GPT-6 Sol: specs side by side

	GPT-6.1 Sol	GPT-6 Sol
Model ID	`gpt-6.1-sol`	`gpt-6-sol`
Context window	1,050,000 tokens	1,050,000 tokens
Max output	128,000 tokens	128,000 tokens
Knowledge cutoff	April 30, 2026	April 20, 2026
Input / output per 1M	$2.00 / $10.00	$2.00 / $10.00
Cached input per 1M	$0.10	$0.20
Reasoning effort	low → max	none, low → max
Tool calling	Responses API only	Responses API; Chat Completions only with effort `none`
Image input	Yes	Yes
Audio / video input	No	No

Figures come from OpenAI's model documentation as summarised in launch-week coverage (CometAPI, September 30, 2026). Requests above 272K input tokens are billed at higher rates on both; Batch and Flex are 50% cheaper. Check OpenAI's pricing page before you budget.

What improved in GPT-6.1

OpenAI's own evaluations (not independent tests) report:

Coding: +6.4 percentage points on DeepSWE v1.1 versus GPT-6 Sol's best result – reached at a lower reasoning effort, so it is not a matched comparison.
Business agents: +4.8 points on AutomationBench at medium effort for both models.
Computer use: +7 points on the OSWorld 2.0 offline set at max effort, at less than half the task cost.
Science agents: more than double GPT-6 Sol's score on Terminal-Bench Science at max effort.
Factuality: on a set of difficult prompts at low effort, responses with errors fell from 11.4% to 7.7%.
Honest failures: in a deliberately broken-search test, failing to tell the user search was broken fell from 4.9% to 2.1%.

The pattern: GPT-6.1 does more useful work per token on long, multi-step tasks. For short chat answers you will notice much less difference.

What did not change

Price per token for uncached input and output.
Context and output limits.
Modalities: text and image in, text out; no native audio/video input or image output.
No fine-tuning on either model.

Should you switch from GPT-6 to GPT-6.1?

Switch (or at least test) if you:

run coding agents or long tool-using workflows;
reuse long system prompts or documents – the cheaper cached input halves that part of the bill;
care about the model admitting when a tool failed.

Stay on GPT-6 Sol for now if you:

depend on reasoning effort none for the lowest latency;
call tools through Chat Completions and can't move to the Responses API yet;
have a stable production setup and no time to re-test.

How to test before switching

Take 20–50 real tasks from your logs.
Run both models with the same prompts, tools and reasoning effort (start at low for 6.1).
Compare task success, latency, real cache hits and total cost per finished task – not just price per token.
Move traffic gradually and keep GPT-6 Sol as a fallback for a week.

In ChatGPT (not the API)

In the ChatGPT app you don't pick token prices; OpenAI decides which model powers each plan and mode, and those defaults change. Look at the model picker in your account for what you currently have. If you mostly want better answers, a clearer prompt usually matters more than the version number – our free ChatGPT prompt generator turns a rough request into a structured prompt.

FAQ

Is GPT-6.1 better than GPT-6? GPT-6.1 Sol beats GPT-6 Sol on OpenAI's reported coding, computer-use, automation and factuality evaluations. GPT-6 Astra, the flagship, is still a separate and more expensive model.

Is GPT-6.1 more expensive than GPT-6? No. GPT-6.1 Sol and GPT-6 Sol both cost $2 per million input tokens and $10 per million output tokens; GPT-6.1 Sol's cached input is cheaper ($0.10 vs $0.20).

When was GPT-6.1 released? OpenAI announced GPT-6.1 Sol on September 29, 2026. GPT-6 Sol came out on September 22, 2026.

Does GPT-6.1 have a bigger context window? No. Both have a 1.05-million-token context window and 128K maximum output.

What breaks when I migrate to GPT-6.1 Sol? Reasoning effort none is gone (the lowest is low), and function calling works only through the Responses API.

How does GPT-6.1 compare with Claude Opus 5.5? See our GPT-6.1 vs Opus 5.5 comparison.