$ cat wiki/models/gpt-6-sol.md
GPT-6 Sol
Compared with
- Claude Opus 5.5
- MiMo-V2.6-Pro
- Ternary Bonsai 2 27B
- Fugu Max
- Kimi K2.8 Preview
- DeepSeek V4.1-Flash
- K2 Horizon
- Gemini 3.8 Flash
- Muse Spark 1.3
- Hy4 preview
- GLM-5.3-Flash
- Granite 4.2
- Grok 4.6
- Laguna S 2.1
- Inkling
- LongCat-2.0
- MiniMax M3
- GPT-6 Luna
- Fugu Ultra v2
- GPT-Image-2.5 Flare
- GPT-Image-2.5 Sunburst
- Astra
- Claude Fable 5.1
- GLM-5.3
- Qwen 3.8 27B
- DeepSeek V4-Pro-0813
- Gemini 3.7 Flash
- Muse Glimmer
- Muse Spark 1.2
- Qwen 3.8 Max
- DeepSeek V4-Flash
- Claude Opus 5
- Gemini 3.5 Flash-Lite
- Gemini 3.6 Flash
- DeepSeek V4
- Kimi K3
- GPT-5.6 Sol
- Grok 4.5
- Claude Sonnet 5
- GLM-5.2
- Claude Fable 5
- Claude Opus 4.8
- Gemini 3.5 Flash
- Grok Build
- Claude Opus 4.7
- Muse Spark
OpenAI's 2026-09-22 cost-efficient high-end model of the GPT-6 series, released alongside GPT-6 Luna and positioned below the flagship Astra — 19 days after Astra itself (source).
The release's claim is price, not capability: Sol comes within 1.1 points of Claude Fable 5's best published DeepSWE v1.1 score while OpenAI puts its cost per task at roughly 80% lower.
Do not confuse this model with GPT-5.6 Sol (and Terra, Luna). They are different
models one generation apart, and GPT-5.6 Sol is this model's named predecessor
at twice the price. The slugs differ and scripts/spec-check.py matches slugs
exactly, which is the reason that distinction is load-bearing rather than
cosmetic.
Not read first-party. openai.com answers EGRESS_BLOCKED from the cloud
sandbox, as on 2026-09-22; thenewstack.io and www.digitalapplied.com are
also blocked. The artefact's identity is fixed by the announcement URL carried
in state/prefetch.json from OpenAI's own feed, timestamped
Tue, 22 Sep 2026 18:00:00 GMT; figures come from two search passes with
different queries.
Spec
| Attribute | Value |
|---|---|
| Developer | OpenAI |
| Released | 2026-09-22 |
| Announced | 2026-09-22 |
| Context window | 1.05M tokens |
| Pricing | $2/M input · $10/M output · cached input $0.20/M |
| License | proprietary (API-only; no weight release) |
| Availability | ChatGPT Work and Codex (Plus, Pro, Business, Enterprise, Edu); OpenAI API as gpt-6-sol. Not yet in Chat |
| Catalogue id | unknown |
| Rows with no slot in this schema: max output 128,000 tokens, and **reasoning | |
settings from none through max**. Cached input carries a 90% discount. |
Catalogue id is unknown rather than absent — openrouter.ai is blocked from
this sandbox and the daily spec-check Action is what will resolve whether the
slug gpt-6-sol reaches the catalogue entry.
Release Date
2026-09-22. Available in ChatGPT Work and Codex from launch day; Chat availability had not landed as of capture.
Benchmarks
DeepSWE v1.1 is the only benchmark published for this model (source):
| Model | Effort | Score |
|---|---|---|
| Claude Fable 5 | xhigh | 69.9% |
| GPT-6 Sol | max | 68.8% |
| GPT-6 Luna | max | 66.6% |
| Two qualifications belong with those numbers. The efforts differ — Sol's | ||
figure is at max and Fable 5's at xhigh, which are each vendor's own top | ||
| setting but not the same setting, and this wiki has a page for why that matters | ||
| (Eval Harness Configuration). And **one benchmark is the whole | ||
| published record**: there is no reasoning, knowledge, multimodal or agentic | ||
| figure for Sol in anything read, so the 68.8% cannot be generalised beyond | ||
| software engineering. |
Cost claim: Sol's cost per task on DeepSWE v1.1 is roughly 80% lower than Claude Fable 5's. This is a derived ratio from OpenAI, not a measured figure this wiki can check.
Use Cases
OpenAI's framing is the price-performance frontier rather than a new capability ceiling — the series flagship Astra remains above it. The pairing with GPT-6 Luna gives a two-tier split: Sol for work that needs near-frontier coding, Luna for volume.
The launch shipped with a companion change to prompt caching for GPT-6
(https://openai.com/index/better-prompt-caching-for-gpt-6, announced
Tue, 22 Sep 2026 21:00:00 GMT), which is consistent with the 90% cached-input
discount but was not read — the post is on a blocked host and nothing in this
run establishes its contents.
Compared To
- GPT-5.6 Sol (and Terra, Luna) — the direct predecessor, at $4/$20. GPT-6 Sol halves both sides.
- GPT-6 Luna — the cheaper sibling, launched the same day, 20× cheaper on input ($0.10 against $2.00) for 2.2 points less on DeepSWE v1.1.
- Astra — the GPT-6 flagship, released 19 days earlier and still positioned above Sol. Astra is the first model OpenAI treated as "Critical" for cybersecurity under its Preparedness Framework; nothing read states how Sol is classified under that framework, which is a gap worth naming on a model shipping this close behind it.
- Claude Opus 5.5 — Anthropic's release of the same day, at $4/$20. The two launches share no benchmark: Anthropic published Terminal-Bench 4.0, FrontierCode and CursorBench and headlined no SWE-bench family result, while OpenAI published only DeepSWE v1.1. No vendor-material comparison between them is possible.
Sources
- Introducing GPT-6 Sol and Luna (snapshot)
- Better prompt caching for GPT-6 — announced the same day; not read, host blocked
Conflicting Reports
Coverage read this run splits on how to characterise the release, on identical figures. VentureBeat and The New Stack lead on the price cut — "slashing API costs 50% or more" — while the-decoder.com reads the same launch as "cut prices in half but barely move the needle on performance". Both are consistent with 68.8% at max effort against GPT-5.6 Sol's predecessor pricing; they differ on whether a halved price with roughly flat capability is the story or the complaint. Recorded rather than resolved.