GPT-6 Sol Review: Fewer Mistakes Than GPT-5.6 Sol at Half the Price

On September 22, 2026, OpenAI released GPT-6 Sol alongside GPT-6 Luna as a lower-cost reasoning model engineered with similar training methods to GPT-6 Astra. GPT-6 Sol first launched in ChatGPT Work and Codex for paid plans. On October 7, 2026, OpenAI made it the model behind GPT-6 in ChatGPT Chat for Plus, Pro, Business, and Enterprise tiers. GPT-6 Sol costs half of GPT-5.6 Sol's promotional application programming interface (API) token prices. OpenAI's API docs say it is "Built to power complex coding and agentic workflows."

On OpenAI's published tests, GPT-6 Sol makes about half as many mistakes as GPT-5.6 Sol. It does so at half the API price. GPT-6.1 Sol was released September 29, 2026. It scores higher on coding and agent tests at the same standard token price and charges half as much for cached input.

The Verdict on GPT-6 Sol

GPT-6 Sol is a good pick for paid ChatGPT plans and for API teams already running gpt-6-sol. For new coding and agent pipelines, GPT-6.1 Sol is the better pick at the same standard token price. In daily conversational workflows, the October update delivers faster web search responses for Plus, Pro, Business, and Enterprise tiers. In the API, GPT-6 Sol costs $2.00 per million input tokens. Output tokens cost $10.00 per million.

In OpenAI's own tests, GPT-6 Sol outscored Claude Opus 5 on AutomationBench at 9 percent of Opus 5's cost per task. GPT-6 Sol also made about half as many mistakes as GPT-5.6 Sol on OpenAI's evaluation of user-flagged conversations. GPT-6.1 Sol outperforms GPT-6 Sol on several benchmarks. At GPT-6 Sol's launch, OpenAI called GPT-6 Astra its best model across the board.

There is no immediate pressure to migrate an existing implementation running successfully on GPT-6 Sol. OpenAI lists no deprecation date for the gpt-6-sol snapshot. For a new build, GPT-6.1 Sol charges $0.10 per million cached input tokens instead of $0.20. It also scores higher on DeepSWE, AutomationBench, and OSWorld 2.0.

Published Benchmark Evidence Across Automation and Coding Tasks

OpenAI's published results put GPT-6 Sol close to or ahead of Claude models on agent and coding tests, at a lower cost per task. On AutomationBench 1.0.6, which measures multi-step task execution across 47 tools, GPT-6 Sol operating at extra-high reasoning effort scored 33.2 percent at an expense of $0.27 per task. That score surpassed Claude Opus 5 at maximum effort. Claude Opus 5 scored 26.9 percent at 11.1 times GPT-6 Sol's cost per task.

On DeepSWE version 1.1, GPT-6 Sol at maximum reasoning effort achieved a score of 68.8 percent. It finished within 1.1 percentage points of Claude Fable 5's highest score, 69.9 percent at xhigh effort. GPT-6 Sol's cost per task was about 80 percent lower. In desktop environment testing on the OSWorld 2.0 offline evaluation set, GPT-6 Sol at extra-high effort scored 60.5 percent. Claude Opus 5 scored 60.3 percent at medium effort, and GPT-6 Sol's cost per task was about 80 percent lower.

On the Agents' Last Exam V1 benchmark, GPT-6 Sol reached 56.4 percent at maximum effort. That is above Claude Opus 5's highest score in the evaluation, at 60 percent lower cost per task. In factual reliability assessments across user-flagged conversations, OpenAI reported that GPT-6 Sol committed approximately half as many factual errors as GPT-5.6 Sol. OpenAI ran these GPT-6 Sol benchmarks in its research environment or through its API. OpenAI says this may give slightly different output from production ChatGPT. OpenAI took the competitor scores from publicly available reports.

Intelligent UI Integration in ChatGPT Workflows

Intelligent UI in ChatGPT has no separate usage quota, so existing model, tool, and plan allowances still apply. Introduced on October 7, 2026, through OpenAI's rollout, this capability launched alongside the GPT-6 expansion in ChatGPT. Intelligent UI works at Instant through Extra High effort. Extra High itself is limited to Pro, Business, and Enterprise plans.

For questions requiring live web search, OpenAI reports that GPT-6 Instant begins answering 44 percent sooner on average than GPT-5.6 Instant. On an internal evaluation of agentic tasks, GPT-6 Extra High begins answering in the same time as GPT-5.6 Medium. It gets a better overall score than GPT-5.6 Extra High.

Intelligent UI does not work at Pro effort. That effort uses GPT-6 Pro powered by GPT-6 Astra. Workplace administrators on ChatGPT Enterprise accounts also retain settings controls that allow them to disable GPT-6 Sol access across their corporate workspaces.

API Token Economics and Pricing Structure

GPT-6 Sol's API pricing is 50 percent below GPT-5.6 Sol's promotional rates for both input and output tokens. Standard requests to the gpt-6-sol snapshot cost $2.00 per million input tokens and $10.00 per million output tokens, as documented on the OpenAI API model page. Prompt caching reduces cached input reads to $0.20 per million tokens, representing a 90 percent discount against uncached inputs, while cache writes are billed at $2.50 per million tokens.

Batch processing and Flex processing cut standard input and output expenses by 50 percent. Fast mode doubles applicable token rates to prioritize throughput. In long-context workflows where prompt sizes exceed 272,000 input tokens, OpenAI applies a pricing multiplier that doubles input and cache rates and raises output token rates by 1.5 times across the full request.

Rate limit tiers allocate throughput according to total organization credit purchases, starting with Build at 5,000 Requests Per Minute (RPM) and 1,000,000 Tokens Per Minute (TPM). Grow reaches 15,000 RPM and 40,000,000 TPM. European Union (EU) data residency is available with Standard, Fast, Flex, and Batch processing, and regional processing adds a 10 percent premium where available.

How GPT-6 Sol Compares with Other OpenAI Models

Within the OpenAI model lineup, GPT-6 Sol serves as an intermediate reasoning system positioned between GPT-6 Luna and GPT-6 Astra. In Codex, GPT-6 Sol uses 50 credits per million input tokens and 250 per million output tokens at Standard speed, half the 100 and 500 that GPT-5.6 Sol uses. In the ChatGPT model menu, GPT-6 replaces Latest, while explicit GPT-5.6 Sol selections stay on GPT-5.6 (GPT-6 Sol vs GPT-5.6 compares the two).

OpenAI released GPT-6.1 Sol on September 29, 2026, one week after GPT-6 Sol. GPT-6.1 Sol keeps standard rates at $2.00 and $10.00 but cuts cached input pricing to $0.10 per million tokens, which OpenAI states is 50 percent cheaper than GPT-6 Sol caching. GPT-6.1 Sol also eclipses GPT-6 Sol by 6.4 percentage points on DeepSWE version 1.1, 4.8 percentage points on AutomationBench, and seven percentage points on OSWorld 2.0 at maximum reasoning effort.

Two API settings also differ. GPT-6 Sol supports the none reasoning effort, which GPT-6.1 Sol does not, and GPT-6.1 Sol offers an Ultrafast mode that GPT-6 Sol lacks. GPT-6 Sol's knowledge cutoff is April 20, 2026, and GPT-6.1 Sol's is April 30, 2026 (see GPT-6.1 Sol vs GPT-6 Sol).

Documented Technical Weaknesses and Operational Limits

Documented technical limitations for GPT-6 Sol include regressions on medical knowledge evaluations, the absence of an Ultrafast execution tier, and restricted function calling under standard reasoning modes. On HealthBench evaluations detailed in the OpenAI system card, GPT-6 Sol scored 53.2, dropping 3.8 points below GPT-5.6 Sol, while HealthBench Hard dropped 3.0 points to 30.1. OpenAI ties the regressions to substantially shorter final answers.

GPT-6 Sol supports function calling in Chat Completions only when reasoning effort is set to none. OpenAI tells developers to use the Responses API for reasoning with tools. GPT-6 Sol takes text and image input. GPT-6 Sol returns text only. It does not support audio, video, fine-tuning, embeddings, or the Assistants API.

The GPT-6 Sol limits OpenAI does publish are API rate limits by usage tier and estimated message ranges in Work and Codex. In ChatGPT Work and Codex, Plus and Standard Business seats receive an estimated allowance of 15 to 150 local messages per five-hour window. This represents an operational estimate rather than a guaranteed hard quota. OpenAI does not publish parameter counts, training compute, or numeric message caps for GPT-6 Sol at Medium, High, or Extra High in ChatGPT Chat.

Target Use Cases and Alternative Model Guidance

Free and Go users cannot get GPT-6 Sol at all, so the choice applies only to paid ChatGPT plans and API buyers. GPT-6 Sol serves teams using ChatGPT Plus, Pro, and Business who require fast web search responses and everyday conversational reasoning. In API deployments, it serves existing gpt-6-sol implementations.

GPT-6 Sol is less suited for teams designing new agentic coding pipelines that rely heavily on prompt caching. Those implementations should select GPT-6.1 Sol. It captures a 50 percent lower cached input price of $0.10 per million tokens and a 6.4 percentage point gain on DeepSWE code benchmarks. Similarly, lower-cost workloads can use GPT-6 Luna at $0.10 per million input tokens, while GPT-6 Astra serves requests requiring the highest intelligence.

This verdict would change if OpenAI set a retirement date for gpt-6-sol or cut its $0.20 cached input price to match GPT-6.1 Sol's $0.10. If you already use gpt-6-sol, read OpenAI's migration guidance for GPT-6.1 Sol. Run a sample of your production prompts on both models before switching.

How to use GPT-6 Sol

You do not host GPT-6 Sol yourself — you use it through a tool, so "getting started" really means choosing the right one.

The fastest way to put GPT-6 Sol to work day to day is inside an AI IDE, and Cursor is the most popular — it supports it directly, so you can be working in minutes. The maker's own option is Codex for GPT-6 Sol, if you want the native experience. Prefer a different editor? Windsurf, Zed, and GitHub Copilot drive these models too.