OpenAI
GPT-6 Sol: price, context window, and caching
The mid-priced GPT-6 model, which OpenAI pitches for complex coding and agent workflows and which the Codex docs recommend for complex coding.
Released September 22, 2026 · Prices as of September 28, 2026
In OpenAI’s words
“Built to power complex coding and agentic workflows.”
Facts
Specs and prices
| Fact | GPT-6 Sol |
|---|---|
| Maker | OpenAI |
| API model id | gpt-6-sol |
| Released | September 22, 2026 |
| Status | Current |
| Context window | 1.05M tokens |
| Max output | 128K tokens |
| Open weights | No |
| Input, per 1M tokens | $2 |
| Cache hit, per 1M | $0.20 |
| Cache write, per 1M | $2.50 |
| Output, per 1M tokens | $10 |
| Runs in | Codex, OpenCode, OpenRouter, and GitHub Copilot |
Standard API rates in US dollars, as published by the maker on September 28, 2026. Batch and priority tiers, taxes, and subscription plans are not included. GPT-6 Sol: Requests over 272K input tokens cost 2x for input and cache and 1.5x for output, for the whole request.
Good to know
- The default reasoning effort is medium, in the API and in Codex.
- Codex suggests moving from GPT-5.6 Sol, GPT-5.6 Terra, and GPT-5.4 to it.
- It accepts up to 922K input tokens of its context window.
Cost
What typical work costs
Example token counts at GPT-6 Sol’s published rates. On the agentic session, caching saves $3.40 against billing every token as ordinary input.
| Agentic coding session, 100K input, 400K written to cache, 2M read from cache, 50K output | $2.10 |
|---|---|
| Large one-off review, 150K input with no cache hits, 10K output | $0.40 |
| Output-heavy generation, 30K input, 80K output | $0.86 |
| A month of sessions, 110 sessions: 5 a day, 22 working days | $231.00 |
Prompt caching
How OpenAI bills cached tokens
OpenAI
Prompt caching is on by default. From GPT-5.6 on you can also mark up to four explicit cache breakpoints, while GPT-5.5 and earlier cache automatically only.
From GPT-5.6 on, a cache write costs 1.25x the uncached input price and a cache hit costs 0.1x. GPT-5.5 and earlier add no charge for writing the cache: written tokens are billed as ordinary input, and a hit costs 0.1x on the models compared here.
On GPT-5.6 and later, a cached prefix stays reusable for at least 30 minutes after its last use, and caching starts at 1,024 input tokens.
Source: OpenAI: Prompt caching
GPT-6 Sol compared
Claude Fable 5.1 vs GPT-6 Sol
Claude Fable 5.1 costs 5x what GPT-6 Sol does per token, and caching leaves that ratio intact. How Anthropic's top model compares with OpenAI's middle one.
Claude Opus 5.5 vs GPT-6 Sol
Claude Opus 5.5 and GPT-6 Sol launched the same day. Opus 5.5 lists at 2x Sol's prices, and its 1-hour cache writes stretch a coding session to 2.1x.
Claude Sonnet 5 vs GPT-6 Sol
Claude Sonnet 5 and GPT-6 Sol list the same $2 input and $10 output rates. Cache writes decide the gap: $2.40 against $2.10 for one coding session.
DeepSeek-V4-Pro vs GPT-6 Sol
DeepSeek-V4-Pro costs $0.95 for a cached coding session against $2.10 on GPT-6 Sol. How the gap forms, and what DeepSeek's Codex support does and doesn't mean.
GLM-5.3 vs GPT-6 Sol
GLM-5.3 costs 31% less than GPT-6 Sol on an agentic coding session, $1.44 against $2.10. How OpenAI's write fee and 272K rule compare with Z.ai's rates.
GPT-6 Astra vs GPT-6 Sol
GPT-6 Astra costs 5x as much as GPT-6 Sol on every token, cached or not. What OpenAI built each for, which one Codex picks, and what a session costs.
GPT-6 Sol vs Gemini 3.1 Pro Preview
GPT-6 Sol and Gemini 3.1 Pro Preview both charge $2 input and $0.20 per cache hit. Which one costs less flips by workload, so limits and status decide.
GPT-6 Sol vs Gemini 3.8 Flash
Gemini 3.8 Flash costs a third of GPT-6 Sol on a cached coding session, at introductory rates that end December 31, 2026. How the gap changes after that.
GPT-6 Sol vs GPT-5.6 Sol
GPT-6 Sol costs half as much as GPT-5.6 Sol on every rate, and Codex suggests the move. What changes, what the promo pricing means, and what stays put.
GPT-6 Sol vs GPT-5.6 Terra
GPT-6 Sol matches GPT-5.6 Terra's input and cache prices and charges less for output. What that means for coding sessions and the move Codex suggests.
GPT-6 Sol vs GPT-6 Luna
GPT-6 Luna costs a twentieth of GPT-6 Sol per token. What OpenAI and the Codex docs say each tier is for, and what the gap means for coding sessions.
Grok 4.7 vs GPT-6 Sol
Grok 4.7 and GPT-6 Sol launched a day apart at $2 input. GPT-6 Sol wins a cached session, $2.10 to $2.30. Grok 4.7 wins uncached and output-heavy work.
Kimi K3 vs GPT-6 Sol
GPT-6 Sol undercuts Kimi K3 on every rate, and an agentic coding session costs $2.10 against $2.85. Both list 1.05M context, with different limits inside.
Mistral Medium 3.5 vs GPT-6 Sol
Mistral Medium 3.5 undercuts GPT-6 Sol by 25% per token and 32% on a cached coding session. The trade-offs: a 256K window, preview status, and fewer tools.
Qwen3.8-Max vs GPT-6 Sol
Qwen3.8-Max and GPT-6 Sol list the same $2 input rate, and an agentic coding session differs by $0.30. How output, cache writes, and Codex shape the choice.
Your own numbers
See what GPT-6 Sol really costs you.
everyaitoken reads your Codex, OpenCode, and OpenRouter history on your Mac and prices every request at API rates, with what caching saved or cost. $9 once.