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OpenAI 2025-26 lineage

2 min readLarge Language ModelsLast updated:

Editorial illustration: OpenAI 2025-26 lineage

Key facts

GPT-6.1 Sol29 Sep 2026
Latest release
$2 / $10per million input / output tokens
Sol API price
14 Oct 2026API access continues
GPT-5.5 product retirement

OpenAI’s GPT model timeline from August 2025 to GPT-6.1 Sol in September 2026, with current prices and the upcoming GPT-5.5 product retirement.

GPT is OpenAI’s family of language models

GPT models read instructions and produce answers, code and other work. OpenAI offers different sizes and reasoning settings, so the newest release date, price and product availability each answer a different question. The latest release in this timeline is GPT-6.1 Sol, introduced on 29 September 2026.

The family grew from GPT-5 to GPT-6.1

OpenAI’s API changelog records the following releases:

Release Date Main change
GPT-5 7 August 2025 New numbered generation
GPT-5.1 November 2025 Updated GPT-5 family
GPT-5.2 11 December 2025 Instant, Thinking and Pro variants
GPT-5.3-Codex 5 February 2026 Model for coding agents
GPT-5.4 5 March 2026 Thinking and Pro, followed by smaller models
GPT-5.5 23 April 2026 Model release; API access followed on 24 April
GPT-6 Astra 3 September 2026 Higher-capability GPT-6 model
GPT-6 Sol and Luna 22 September 2026 Mid-price and lower-cost GPT-6 models
GPT-6.1 Sol 29 September 2026 Upgrade to Sol at the same standard input and output prices

GPT-5.6’s Luna, Terra and Sol tiers sit between the GPT-5.5 and GPT-6 generations. The individual model pages cover their specifications and launch histories.

Current prices need their own date

On 5 October 2026, GPT-6.1 Sol costs $2 per million input tokens and $10 per million output tokens, with cached input at $0.10. Its model page sets additional rates for long prompts, faster processing and regional processing.

GPT-5.6 Sol’s promotional rate is $4 input and $20 output per million tokens, introduced on 21 August and scheduled to last through at least 21 November 2026. Its earlier $5/$30 launch price is a historical figure.

Product retirement and API retirement have separate dates

GPT-5.5 leaves ChatGPT, ChatGPT Work and Codex on 14 October 2026, while its API remains available, according to OpenAI’s model-access guide.

The API deprecation schedule separately sets 1 April 2027 for GPT-5.3-Codex, GPT-5.1 and GPT-5.4 nano. GPT-5.4-Cyber’s API shutdown date was 1 October 2026. Check the exact model ID in an application against that schedule before planning a migration.

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