AI_SLANG_ENTRY
What Is GPT-5.6 Sol?
GPT-5.6 Sol is the flagship capability tier in OpenAI's GPT-5.6 model family, intended for complex reasoning, coding, professional work, and long-running tool-using workflows.
What does GPT-5.6 Sol mean?
GPT-5.6 Sol is the flagship capability tier in OpenAI's GPT-5.6 model family, intended for complex reasoning, coding, professional work, and long-running tool-using workflows.
Sol is OpenAI's name for the high-capability GPT-5.6 tier. It is a model choice, not a ChatGPT plan, and its API token bill is separate from included subscription usage or product credits.
Origin and usage
OpenAI previewed GPT-5.6 Sol on June 26, 2026, then made the GPT-5.6 family generally available on July 9, 2026. Sol introduced the flagship tier in a naming system where the number marks the generation and Sol, Terra, and Luna mark durable capability tiers.
Source type: product-term. Last checked: 2026-08-25.
Official OpenAI model term. API prices, promotional periods, product availability, model aliases, reasoning modes, and credit rules are dynamic, so this entry separates the current model-page facts from launch pricing and subscription access.
What Sol means in GPT-5.6
OpenAI describes Sol as the flagship capability tier in the GPT-5.6 family. Terra is the balanced lower-cost tier, while Luna is the fastest and most affordable tier for high-volume work.
The generation number and tier name serve different jobs: 5.6 identifies the generation, while Sol, Terra, and Luna are capability tiers that can advance on their own cadence. In the API, the `gpt-5.6` alias routes to `gpt-5.6-sol`.
Preview, general availability, and price changes
- June 26, 2026: OpenAI began a limited preview of Sol, Terra, and Luna.
- July 9, 2026: the GPT-5.6 family became generally available across ChatGPT, Codex, and the OpenAI API.
- July 30, 2026: OpenAI reduced Terra and Luna API prices.
- August 21, 2026: OpenAI introduced a temporary GPT-5.6 Sol API and eligible credit-price reduction.
Current GPT-5.6 Sol API pricing
Last checked on August 25, 2026: OpenAI's model page lists $4 per million input tokens, $0.40 per million cached input tokens, and $20 per million output tokens for GPT-5.6 Sol.
OpenAI says this promotional pricing is available at least through November 21, 2026. The launch article still contains the earlier $5 input and $30 output figures in its body, so the current model page should be checked before quoting a price.
Long context and cache charges
- The documented context window is 1,050,000 tokens, with up to 128,000 output tokens.
- Prompts with more than 272K input tokens are billed at 2x the input rate and 1.5x the output rate for the full request.
- Cache reads use the cached-input rate; explicit cache writes are billed at 1.25x the uncached input rate.
- Tool-specific charges, Batch, Flex, Priority or Fast processing, regional processing, and partner platforms can follow different rules.
Sol vs Terra vs Luna
Use Sol when the cost of a weak answer is high: complex repository work, difficult reasoning, professional analysis, research, or long-running tool coordination. Use Terra when you want a stronger price-performance balance, and Luna for high-volume work where latency and cost matter most.
Model choice and reasoning effort are separate controls. GPT-5.6 supports none, low, medium, high, xhigh, and max reasoning effort. A lower-priced tier or lower effort can be the better production choice if it passes the same representative evals.
API pricing is not a ChatGPT subscription price
Per-token API pricing does not tell you the monthly cost of ChatGPT Plus, Pro, Business, or Enterprise. Included usage, message limits, token-based enterprise billing, product credits, and API usage are separate meters.
Sol Pro and ultra can also describe higher-compute product or reasoning modes. They should not be invented as separate API model slugs when current OpenAI guidance says to keep the selected GPT-5.6 model and configure the supported reasoning mode or effort.
Examples
- Use GPT-5.6 Sol for the migration plan, but route routine classification to Luna.
- The API request used gpt-5.6-sol at medium effort rather than treating Sol as a ChatGPT subscription.
FAQ
Is GPT-5.6 Sol the same as GPT-5.6?
The GPT-5.6 name can refer to the whole Sol, Terra, and Luna family. In the API, OpenAI says the gpt-5.6 alias currently routes to the flagship gpt-5.6-sol model.
How much does GPT-5.6 Sol cost?
As checked on August 25, 2026, OpenAI lists promotional API pricing of $4 per million input tokens, $0.40 per million cached input tokens, and $20 per million output tokens, available at least through November 21, 2026.
When was GPT-5.6 Sol released?
OpenAI began a limited preview on June 26, 2026 and announced general availability for the GPT-5.6 family on July 9, 2026.
Should I use Sol, Terra, or Luna?
Use Sol for the hardest quality-first work, Terra for a balance of capability and cost, and Luna for cost-sensitive, high-volume workloads. Confirm the choice with representative tasks and total cost per successful result.
Does the GPT-5.6 Sol API price include ChatGPT access?
No. API token charges are separate from ChatGPT subscriptions, included usage, message limits, enterprise token billing, and product credit systems.