GPT-5.4 Pro is the premium reasoning tier of the GPT-5.4 family: per OpenAI, it "uses more compute to think harder and provide consistently better answers," producing smarter, more precise responses on tough problems.
- Input
- text image $30/M
- Output
- text $180/M
- Cache read
- $15/M
- Context
- 922K
- Knowledge cutoff
- 2025-08
Benchmarks
Vendor-published: Alibaba (Qwen) Anthropic ByteDance DeepSeek Google MiniMax Moonshot OpenAI Tencent Z.ai
Price in context
Where the price sits among 60 comparable models
The bar shows how this model’s price compares with every other model of the same kind on Synthorai. The cheapest and the most expensive are named at each end. These are base rates; batch, region and cache-write discounts are on the pricing page.
Specs & limits
Tokens
| Context window (vendor spec) | 1,050,000 |
|---|---|
| Max output (vendor spec) | 128,000 |
| Knowledge cutoff | 2025-08 |
Prompt caching
| How it caches | automatic |
|---|---|
| Min prefix | 1,024 |
| Lifetime | 5-10m, up to 1h |
Thinking
| Vendor control | reasoning.effort |
|---|---|
| Accepted values | medium · high · xhigh |
| Default | medium applied when the request sets nothing |
| Can be turned off | No |
| Thinking behaviour | Responses API only; requests may take several minutes, so OpenAI recommends background mode. |
| Parameter | reasoning_effort |
| Values | minimal · low · medium · high the gateway's parameter surface - the vendor mapping above applies |
Model
| Modalities | text + image → text |
|---|
- Higher-compute pro tier
- structured outputs not supported
- multi-turn use is Responses-API-only
- requests may take minutes (background mode recommended)
- 1.05M context
Use GPT-5.4 Pro in 30 seconds
OpenAI-compatible: swap the base_url, keep your SDK. POST /v1/chat/completions
from openai import OpenAI
client = OpenAI(
base_url="https://synthorai.io/v1",
api_key="sk-syn-...",
)
resp = client.chat.completions.create(
model="gpt-5.4-pro",
messages=[{"role": "user", "content": "Summarize this diff"}],
reasoning_effort="medium",
)
print(resp.choices[0].message.content)import OpenAI from "openai";
const client = new OpenAI({
baseURL: "https://synthorai.io/v1",
apiKey: "sk-syn-...",
});
const resp = await client.chat.completions.create({
model: "gpt-5.4-pro",
messages: [{ role: "user", content: "Summarize this diff" }],
reasoning_effort: "medium",
});
console.log(resp.choices[0].message.content);curl https://synthorai.io/v1/chat/completions \
-H "Authorization: Bearer sk-syn-..." \
-H "Content-Type: application/json" \
-d '{
"model": "gpt-5.4-pro",
"messages": [{"role": "user", "content": "Hello"}],
"reasoning_effort": "medium"
}'package main
import (
"context"
"fmt"
"github.com/openai/openai-go/v3"
"github.com/openai/openai-go/v3/option"
)
func main() {
client := openai.NewClient(
option.WithBaseURL("https://synthorai.io/v1"),
option.WithAPIKey("sk-syn-..."),
)
resp, _ := client.Chat.Completions.New(context.TODO(), openai.ChatCompletionNewParams{
Model: "gpt-5.4-pro",
Messages: []openai.ChatCompletionMessageParamUnion{
openai.UserMessage("Summarize this diff"),
},
ReasoningEffort: openai.ReasoningEffortMedium,
})
fmt.Println(resp.Choices[0].Message.Content)
}import com.openai.client.OpenAIClient;
import com.openai.client.okhttp.OpenAIOkHttpClient;
import com.openai.models.chat.completions.*;
import com.openai.models.ReasoningEffort;
OpenAIClient client = OpenAIOkHttpClient.builder()
.baseUrl("https://synthorai.io/v1")
.apiKey("sk-syn-...")
.build();
ChatCompletion resp = client.chat().completions().create(
ChatCompletionCreateParams.builder()
.model("gpt-5.4-pro")
.addUserMessage("Summarize this diff")
.reasoningEffort(ReasoningEffort.MEDIUM)
.build());
System.out.println(resp.choices().get(0).message().content().orElse(""));About GPT-5.4 Pro
- It keeps the 1,050,000-token context window (vendor spec) and 128K max output, accepts image input, and supports reasoning effort at medium, high, and xhigh; long-running requests may take several minutes, so background execution is recommended.
- The absence of none and low is the point of the tier: its floor is deliberation, not speed.
- OpenAI restricts it to the Responses API, explaining that this is what allows multi-turn model interactions before a request is answered, and the Batch API is explicitly unsupported on this model.
- Its tool list covers function calling, web search, file search, tool search, image generation, apply patch, computer use, and MCP.
- The same long-context billing rule as GPT-5.4 applies: prompts above 272K input tokens are charged at 2x input and 1.5x output for the whole request.
- Knowledge cutoff is August 2025, and the shipping snapshot is dated March 2026.
- Reserve it for problems where a better answer is worth minutes of latency and several times the per-token cost.
- Synthorai makes GPT-5.4 Pro callable through its OpenAI-compatible interface right alongside the standard models.
FAQ
Is the GPT-5.4 Pro API free to try?
Yes: new accounts get 10 trial calls and up to $1 in free credit, no card required. At $30/M input tokens, that credit alone covers roughly 4 requests of ~8K tokens against GPT-5.4 Pro.
What is GPT-5.4 Pro best at?
Uses more compute to think harder; consistently better answers on tough problems; background execution for multi-minute requests. See the About section for the full picture from the vendor's own release notes.
How much does GPT-5.4 Pro cost?
GPT-5.4 Pro costs $30 per million input tokens and $180 per million output tokens on Synthorai. That is the provider's list price, with no platform markup. Cached input tokens bill at $15/M.
Does GPT-5.4 Pro support prompt caching?
Yes, automatically: OpenAI-served prompts cache with no code changes. Cached input tokens bill at $15/M vs $30/M uncached; prompts need a 1,024-token stable prefix to cache (TTL 5-10m, up to 1h). Prompt caching guide →
How do I get access to GPT-5.4 Pro?
Point your existing OpenAI SDK at base_url="https://synthorai.io/v1", set model="gpt-5.4-pro", and you're done. One API key covers every model on the gateway.
What is GPT-5.4 Pro's knowledge cutoff?
GPT-5.4 Pro's knowledge cutoff is 2025-08, per the vendor's official documentation (as of 2026-07-09).
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Every value on this page is transcribed from the vendor's own documentation, linked above, and carries the date it was checked. Prices are compared across the catalogue; specification values that vendors define differently are shown with the difference stated rather than charted. Nothing here is measured by us, and nothing is scored.