GPT-5.6 Sol API pricing and setup
GPT-5.6 Sol (gpt-5.6-sol) is a OpenAI model. It is available through the relay.fast API with one relay.fast key and pay-as-you-go billing.
Prices checked from the live catalog. "From" is the lowest price among the relay.fast sources that currently serve the model. The price you pay depends on the source your request uses and can change on any day. The pricing page always shows current values.
| Official input price | $5 per 1M tokens |
|---|---|
| Official output price | $30 per 1M tokens |
| relay.fast input from | $0.075 per 1M tokens |
| relay.fast output from | $0.45 per 1M tokens |
| Cache read from | $0.0075 per 1M tokens |
| Lower than the official price by | up to 98% |
| Context window | 1M tokens |
| Endpoints | /v1/chat/completions |
requests above 272K input tokens cost more
Example request
Keep the key in the RELAY_FAST_API_KEY environment variable.
curl https://relay.fast/v1/chat/completions \
-H "Authorization: Bearer $RELAY_FAST_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model":"gpt-5.6-sol","messages":[{"role":"user","content":"Hello"}]}'Use GPT-5.6 Sol in coding tools
Setup guides: Claude Code, Codex, Cursor, Cline, Kilo Code, OpenCode, Aider. The API docs have one-command installers.
Frequently asked questions
How much does the GPT-5.6 Sol API cost?
On 2026-11-05, relay.fast charges from $0.075 per 1M input tokens and $0.45 per 1M output tokens for GPT-5.6 Sol, against the official $5 and $30. The price depends on the source your request uses and can change; https://relay.fast/pricing/gpt-5.6-sol shows the current value.
What is the context window of GPT-5.6 Sol?
GPT-5.6 Sol accepts up to 1M tokens of context in the relay.fast catalog. Output limits depend on the model and client settings.
Which API endpoint does GPT-5.6 Sol use?
Call /v1/chat/completions with a relay.fast API key. OpenAI-compatible SDKs use the base URL https://relay.fast/v1.
Do I need a OpenAI account to use GPT-5.6 Sol?
No. You use a relay.fast account and API key. relay.fast is an independent API gateway and is not affiliated with OpenAI.
Other OpenAI models
GPT-5.5 · GPT-5.6 Luna · GPT-5.6 Terra · GPT-6 Astra · GPT-6 Luna · GPT-6 Sol · GPT-6.1 Sol · GPT-6.1 Terra