GPT-6 Astra vs GPT-5.6 Sol
GPT-5.6 Sol is the lower-priced of the two on Router One at base-tier rates (GPT-6 Astra and GPT-5.6 Sol: request input ≤ 272,000 tokens) — about 63% less on a 1M-input + 1M-output mix. Both carry a 1.05M context window. Both answer on /v1/chat/completions and /v1/responses (Codex CLI). GPT-6 Astra counts against the Flagship models allowance on Max and Ultra; GPT-5.6 Sol counts against the Premium models allowance on Pro, Max and Ultra.
GPT-6 Astra and GPT-5.6 Sol compared on current per-token rates, context window, and capabilities — both callable through one OpenAI-compatible endpoint with per-request cost traces.
GPT-6 Astra vs GPT-5.6 Sol: rates, context window, and capabilities
| Spec | GPT-6 Astra | GPT-5.6 Sol |
|---|---|---|
| Input / 1M tokens | $2.00 | $0.50 |
| Output / 1M tokens | $10.00 | $4.00 |
| Cached input / 1M tokens | $0.20 | $0.25 |
| Context window | 1.05M | 1.05M |
| Capabilities | Chat, Streaming, Tool calling, Vision | Chat, Streaming, Tool calling, Vision |
| Subscription plans | Flagship models — Max, Ultra | Premium models — Pro, Max, Ultra |
| Detail page | GPT-6 Astra | GPT-5.6 Sol |
GPT-6 Astra: request input ≤ 272,000 tokens: Input $2.00 / 1M tokens, Output $10.00 / 1M tokens, Cache write $2.50 / 1M tokens, Cached input $0.20 / 1M tokens; request input > 272,000 tokens: Input $4.00 / 1M tokens, Output $15.00 / 1M tokens, Cache write $5.00 / 1M tokens, Cached input $0.40 / 1M tokens. The total input tokens in each request select the tier; its rates apply to the whole request, not only tokens above the threshold.
GPT-5.6 Sol: request input ≤ 272,000 tokens: Input $0.50 / 1M tokens, Output $4.00 / 1M tokens, Cache write $0.50 / 1M tokens, Cached input $0.25 / 1M tokens; request input > 272,000 tokens: Input $1.00 / 1M tokens, Output $4.50 / 1M tokens, Cache write $6.25 / 1M tokens, Cached input $0.50 / 1M tokens. The total input tokens in each request select the tier; its rates apply to the whole request, not only tokens above the threshold.
What does 1M tokens cost on GPT-6 Astra vs GPT-5.6 Sol?
Base-tier rates: For a workload of 1M input plus 1M output tokens at current rates: GPT-6 Astra comes to $12.00, GPT-5.6 Sol comes to $4.50 — GPT-5.6 Sol is about 63% cheaper on this mix. Real workloads skew heavily toward input tokens, so weigh the input rate by your own ratio; the cached-input row above is the posted catalog rate for that model.
Switch between GPT-6 Astra and GPT-5.6 Sol
The API key, base URL and endpoints stay the same, but GPT-5.6 Sol code may still need changes before it runs on GPT-6 Astra. Per OpenAI's GPT-6 guide (checked 2026-10-01), GPT-6 Astra does not accept the none reasoning effort (OpenAI suggests low), takes no temperature, top_p or logprobs settings and takes tool calls only on the Responses API, so GPT-5.6 Sol code that sends tools on /v1/chat/completions should move to /v1/responses first. On a Pro, Max or Ultra plan the billing changes too: as of the 2026-10-01 plan response, GPT-6 Astra counts against the Flagship models allowance on Max and Ultra (on Pro it bills the wallet), while GPT-5.6 Sol counts against the Premium models allowance on Pro, Max and Ultra.
curl https://api.router.one/v1/chat/completions \
-H "Authorization: Bearer sk-your-router-one-key" \
-H "Content-Type: application/json" \
-d '{"model": "openai/gpt-6-astra", "messages": [{"role": "user", "content": "Hello"}]}'
# Same request, other model — change one string:
# "model": "openai/gpt-5.6-sol"FAQ
Is GPT-6 Astra cheaper than GPT-5.6 Sol?
Compared at base-tier rates (GPT-6 Astra and GPT-5.6 Sol: request input ≤ 272,000 tokens). Input: GPT-6 Astra $2.00 vs GPT-5.6 Sol $0.50 / 1M tokens; GPT-5.6 Sol has the lower rate. Output: GPT-6 Astra $10.00 vs GPT-5.6 Sol $4.00 / 1M tokens; GPT-5.6 Sol has the lower rate. Total cost depends on the workload's input, output and cache usage. GPT-6 Astra: request input ≤ 272,000 tokens: Input $2.00 / 1M tokens, Output $10.00 / 1M tokens, Cache write $2.50 / 1M tokens, Cached input $0.20 / 1M tokens; request input > 272,000 tokens: Input $4.00 / 1M tokens, Output $15.00 / 1M tokens, Cache write $5.00 / 1M tokens, Cached input $0.40 / 1M tokens. The total input tokens in each request select the tier; its rates apply to the whole request, not only tokens above the threshold. GPT-5.6 Sol: request input ≤ 272,000 tokens: Input $0.50 / 1M tokens, Output $4.00 / 1M tokens, Cache write $0.50 / 1M tokens, Cached input $0.25 / 1M tokens; request input > 272,000 tokens: Input $1.00 / 1M tokens, Output $4.50 / 1M tokens, Cache write $6.25 / 1M tokens, Cached input $0.50 / 1M tokens. The total input tokens in each request select the tier; its rates apply to the whole request, not only tokens above the threshold. Rates change; the /models page is the live source of truth.
Is GPT-6 Astra or GPT-5.6 Sol included in a Router One subscription?
GPT-6 Astra counts against the Flagship models allowance on Max and Ultra: Max 150 and Ultra 450 requests per 30-day cycle, shared by every model in that tier. GPT-5.6 Sol counts against the Premium models allowance on Pro, Max and Ultra: Pro 300, Max 1,000 and Ultra 5,000 requests per 30-day cycle, shared by every model in that tier. Requests to GPT-6 Astra or GPT-5.6 Sol above the model's long-context threshold count as more than one quota request. Requests beyond a plan's allowance bill the wallet per token.
Can I switch between GPT-6 Astra and GPT-5.6 Sol without changing code?
The API key, base URL and endpoints stay the same, but GPT-5.6 Sol code may still need changes before it runs on GPT-6 Astra. Per OpenAI's GPT-6 guide (checked 2026-10-01), GPT-6 Astra does not accept the none reasoning effort (OpenAI suggests low), takes no temperature, top_p or logprobs settings and takes tool calls only on the Responses API, so GPT-5.6 Sol code that sends tools on /v1/chat/completions should move to /v1/responses first. On a Pro, Max or Ultra plan the billing changes too: as of the 2026-10-01 plan response, GPT-6 Astra counts against the Flagship models allowance on Max and Ultra (on Pro it bills the wallet), while GPT-5.6 Sol counts against the Premium models allowance on Pro, Max and Ultra.
Where do these numbers come from?
Specs and prices on this page render from the live Router One catalog — the same data as the /models page — and refresh with it. Pricing methodology is documented on /pricing-methodology. Rates on this page were read from the live catalog on 2026-10-22 (UTC) and refresh within the hour.