AI Model Watch
Models / OpenAI

GPT-5.6 Sol

GA

Top 'Sol' tier of the GPT-5.6 family (Sol/Terra/Luna), GA on the API + Codex 2026-07-09 (preview from 2026-06-26). Text+image input, text output, configurable reasoning effort (none/low/medium/high/xhigh/max; the bare gpt-5.6 alias routes here). New caching model: explicit cache breakpoints, 30-min min cache life, cache writes billed 1.25x uncached input, reads keep the 90% discount. Prompts >272K input tokens are billed at 2x input / 1.5x output for the whole request. PRICE CUT, caught 2026-09-04, 14 days late: the fields now carry $4.00 in / $0.40 cached / $20.00 out per 1M (cache write $5.00/M; Batch and Flex 50%; Fast mode 2x). Until 2026-09-04 this row published $5.00/$0.50/$30.00 and said they had been 're-confirmed 2026-08-08' — true when written, superseded on 2026-08-21, when OpenAI's API changelog stated "GPT-5.6 Sol now costs $4 per million input tokens and $20 per million output tokens, representing 20% lower input pricing and 33% lower output pricing"; the model page repeats the same two percentages. It was missed because no step of the daily data routine runs the OpenAI rate reader (scripts/check-price-drift.mjs) — a written instrument outside the playbook. Promo window unchanged and still stated: "GPT-5.6 Sol's promotional pricing is available at least through November 21, 2026" — so these lower rates are a PROMOTIONAL rate with a published floor date, not a confirmed durable one; re-check on 2026-11-21. GPT-5.6 Sol was this catalog's 'current OpenAI flagship' line until 2026-09-03, when OpenAI released GPT-6 Astra as "our most capable model"; Sol's own page now bills it as "Flagship model for complex professional work".

GPT-5.6 Sol by OpenAI costs $4 per 1M input tokens and $20 per 1M output tokens ($8/1M blended), with a 1.1M (1.050.000-token) context window. It is generally available (GA), with a knowledge cutoff of 16 Feb 2026.

Last verified: 26 Sep 2026 · sourced from official provider documentation

Provider
OpenAI
Status
GA
Input price
$4 / 1M tokens
Output price
$20 / 1M tokens
Cached input
$0.4 / 1M tokens
Blended price
$8 / 1M tokens
Context window
1.050.000 tokens (1.1M)
Max output
128.000 tokens
Modality
text, image
Open weights
No — API only
Knowledge cutoff
2026-02-16
Released
9 Jul 2026
API string
gpt-5.6-sol

Source: OpenAI official documentation ↗

See also

Compare GPT-5.6 Sol head-to-head

GPT-5.6 Sol vs Claude Opus 4.8→

$8 vs $10 blended /M · cross-provider

GPT-5.6 Sol vs Gemini 3.8 Flash→

$8 vs $1.50 blended /M · cross-provider

GPT-5.6 Sol vs DeepSeek-V4.1-Flash→

$8 vs $0.525 blended /M · cross-provider

GPT-5.6 Sol vs Grok 4.7→

$8 vs $3 blended /M · cross-provider

GPT-5.6 Sol vs Mistral Large 3→

$8 vs $0.75 blended /M · cross-provider

GPT-5.6 Sol vs Amazon Nova Pro→

$8 vs $1.40 blended /M · cross-provider

FAQ

GPT-5.6 Sol — questions & answers

How much does GPT-5.6 Sol cost?

GPT-5.6 Sol is priced at $4 per 1M input tokens and $20 per 1M output tokens ($8/1M blended at a 3:1 input-to-output ratio), with cached input at $0.4 per 1M tokens.

What is the context window of GPT-5.6 Sol?

GPT-5.6 Sol has a 1.050.000-token context window (1.1M), with up to 128.000 output tokens per request.

Is GPT-5.6 Sol deprecated?

No — GPT-5.6 Sol is generally available (GA) and not currently scheduled for deprecation or retirement in our tracker.

Does GPT-5.6 Sol support image or vision input?

Yes — GPT-5.6 Sol accepts image input. Listed modalities: text, image.

Can I self-host GPT-5.6 Sol?

No — GPT-5.6 Sol is proprietary. Its weights are not publicly released, so it is available only through OpenAI's API (or hosted partners), not for self-hosting.

What is the API model string for GPT-5.6 Sol?

The API model identifier for GPT-5.6 Sol is "gpt-5.6-sol" when calling OpenAI's API.

What is GPT-5.6 Sol's knowledge cutoff?

GPT-5.6 Sol's training knowledge cutoff is 16 Feb 2026.