GPT-5.4 vs Kimi K2.5
GPT-5.4 (2026) and Kimi K2.5 (2026) are agentic coding models from OpenAI and Moonshot AI. GPT-5.4 ships a not-yet-sourced context window, while Kimi K2.5 ships a 256K-token context window. On MMLU PRO, GPT-5.4 leads by a hair. On pricing, Kimi K2.5 costs $0.38/1M input tokens versus $2.5/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Kimi K2.5 is ~553% cheaper at $0.38/1M; pay for GPT-5.4 only for coding workflow support.
Specs
| Released | 2026-03-05 | 2026-03-15 |
| Context window | — | 256K |
| Parameters | — | 1T (MoE, 384 experts) |
| Architecture | decoder only | mixture of experts |
| License | Proprietary | MIT |
| Knowledge cutoff | 2025-08 | - |
Pricing and availability
| GPT-5.4 | Kimi K2.5 | |
|---|---|---|
| Input price | $2.5/1M tokens | $0.38/1M tokens |
| Output price | $15/1M tokens | $1.72/1M tokens |
| Providers |
Capabilities
| GPT-5.4 | Kimi K2.5 | |
|---|---|---|
| Vision | ||
| Multimodal | ||
| Reasoning | ||
| Function calling | ||
| Tool use | ||
| Structured outputs | ||
| Code execution |
Benchmarks
| Benchmark | GPT-5.4 | Kimi K2.5 |
|---|---|---|
| MMLU PRO | 87.5 | 87.1 |
| Google-Proof Q&A | 92.0 | 87.9 |
| MultiChallenge | 69.2 | 61.4 |
| τ-bench | 78.3 | 74.2 |
| Massive Multi-discipline Multimodal Understanding | 82.1 | 84.3 |
Deep dive
On shared benchmark coverage, MMLU PRO has GPT-5.4 at 87.5 and Kimi K2.5 at 87.1, with GPT-5.4 ahead by 0.4 points; Google-Proof Q&A has GPT-5.4 at 92 and Kimi K2.5 at 87.9, with GPT-5.4 ahead by 4.1 points; MultiChallenge has GPT-5.4 at 69.2 and Kimi K2.5 at 61.4, with GPT-5.4 ahead by 7.8 points. The largest visible gap is 7.8 points on MultiChallenge, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on multimodal input: GPT-5.4, reasoning mode: GPT-5.4, tool use: GPT-5.4, and code execution: GPT-5.4. Both models share function calling and structured outputs, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, GPT-5.4 lists $2.5/1M input and $15/1M output tokens, while Kimi K2.5 lists $0.38/1M input and $1.72/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Kimi K2.5 lower by about $5.47 per million blended tokens. Availability is 2 providers versus 7, so concentration risk also matters.
Choose GPT-5.4 when coding workflow support are central to the workload. Choose Kimi K2.5 when coding workflow support, lower input-token cost, and broader provider choice are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which is cheaper, GPT-5.4 or Kimi K2.5?
Kimi K2.5 is cheaper on tracked token pricing. GPT-5.4 costs $2.5/1M input and $15/1M output tokens. Kimi K2.5 costs $0.38/1M input and $1.72/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is GPT-5.4 or Kimi K2.5 open source?
GPT-5.4 is listed under Proprietary. Kimi K2.5 is listed under MIT. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for multimodal input, GPT-5.4 or Kimi K2.5?
GPT-5.4 has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for reasoning mode, GPT-5.4 or Kimi K2.5?
GPT-5.4 has the clearer documented reasoning mode signal in this comparison. If reasoning mode is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for function calling, GPT-5.4 or Kimi K2.5?
Both GPT-5.4 and Kimi K2.5 expose function calling. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Where can I run GPT-5.4 and Kimi K2.5?
GPT-5.4 is available on OpenAI API and OpenRouter. Kimi K2.5 is available on Fireworks AI, OpenRouter, Together AI, Fireworks AI, and NVIDIA NIM. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-04-27. Data sourced from public model cards and provider documentation.