How do you start calling GPT-5?

Use the model ID gpt-5 through the OpenAI-compatible chat completions endpoint. GPT-5 supports test-time routing features and advanced prompt understanding including user-specified reasoning intent.

What is the max output length for gpt-5?

gpt-5 supports up to 128000 output tokens per request. Plan your prompts to stay within this limit, and use the max_tokens or max_completion_tokens parameter to control output length.

When was GPT-5 released, and is it still maintained?

GPT-5 was released on 2025-08-07. Its catalog status is stable. Check the model page for deprecation notices before you build a long-lived integration on it.

Does gpt-5 have a free tier?

GPT-5 is billed per use and the record publishes no free-tier allowance. The current published rates are input $1.2500 per 1M tokens and output $10.0000 per 1M tokens. Trial credit or promotional quota is tied to your account rather than to the model, so check the console before planning around a free tier.

How does gpt-5 compare with other models, and what should you compare?

Compare gpt-5 against models of similar capability and pricing on your actual workload. Evaluate latency, output quality, instruction following, and cost per task. Run side-by-side tests with your own prompts — the best model depends on your specific use case, not just benchmark scores.

Model detail

GPT-5

Provided by OpenAI

Pay-as-you-go

GPT-5 is OpenAI’s most advanced model, offering major improvements in reasoning, code quality, and user experience. It is optimized for complex tasks that require step-by-step reasoning, instruction following, and accuracy in high-stakes use cases. It supports test-time routing features and advanced prompt understanding, including user-specified intent like "think hard about this." Improvements include reductions in hallucination, sycophancy, and better performance in coding, writing, and health-related tasks.

Model specs

Model ID: gpt-5

Context length: 400K
Max output: 128K
I/O modalities
Released: 2025-08

API endpoints

One MixRoute gateway, OpenAI-compatible

OpenAI-compatible /v1/chat/completions POST

Pricing

Flat rate, unit: /1M Tokens

Input

$1.2500 /1M Tokens

Completion

$10.0000 /1M Tokens

Cache read

$0.1250 /1M Tokens

Selection summary

Quickly judge whether it fits your workload

What is this model good for?

Flagship model for complex reasoning and agentic workflows

GPT-5: GPT-5 is our previous model for coding, reasoning, and agentic tasks across domains. We recommend using the latest GPT-6 Astra. Learn more on the Model guidance page. Reasoning.eff. 400,000-token context.

What should you check before using it?

400,000 context, 128,000 output

OpenAI model. Supports tool calling, structured outputs, function calling. Knowledge cutoff: 2024-09-30.

Why use it through MixRoute?

Drop-in via OpenAI-compatible endpoint on MixRoute

Set the model parameter to "gpt-5" and use your MixRoute API key.

Capabilities & compatibility

Unconfirmed capabilities stay "Unknown," no guesses

Tool calling

GPT-5 supports function and tool calls.

EX Send a tools definition; the response returns tool_calls to execute and feed results back.

Structured output

GPT-5 can produce JSON-formatted output on demand.

EX response_format: { type: "json_schema" } forces valid JSON output.

Streaming

GPT-5 supports streamed responses.

EX stream: true streams tokens incrementally, so chat UIs render as they arrive.

Prompt caching

GPT-5 supports prompt caching under supported routing conditions.

EX Keep the system prompt and tool definitions at the start of the request; repeated prefixes are automatically billed at the cache-read rate.

Vision input

GPT-5 can process image inputs alongside text.

EX Pass a base64-encoded image in a image_url content part alongside text messages.

OpenAI SDK

Call GPT-5 through MixRoute's OpenAI-compatible endpoint.

EX Change base_url to https://api.mixroute.ai/v1; everything else follows the OpenAI style.

Token cost estimator

Live estimate from this page's pricing, not an actual bill

Input tokens Max per request 400K

Output tokens Max per request 128K

Requests / month

Cache hit rate 0%

Share of the same prefix read repeatedly, up to 100%

FAQ

GPT-5 is OpenAI’s most advanced model, offering major improvements in reasoning, code quality, and user experience. It is optimized for complex tasks requiring step-by-step reasoning, instruction following, and accuracy, with reduced hallucination and better performance across coding, writing, and analysis.

Get started

01

Create an API key

Generate a key in the Console; one key calls every model.
02

Set the base URL

Fully OpenAI SDK-compatible; just swap the URL to connect.

https://api.mixroute.ai/v1
03

Specify the model ID

In the request's model field, enter:

gpt-5

Create an API key

New users get $5 in free credits

Test this model and alternate routes with the same request format

Start from a real workload, then let quality, total cost, and failure conditions decide whether to send production traffic.

Create an API key View integration docs