Gemini 2.5 Flash vs GPT-5.4
Gemini 2.5 Flash (2025) and GPT-5.4 (2026) are frontier reasoning models from Google DeepMind and OpenAI. Gemini 2.5 Flash ships a 1M-token context window, while GPT-5.4 ships a not-yet-sourced context window. On MMLU PRO, GPT-5.4 leads by 6.6 pts. On pricing, Gemini 2.5 Flash costs $0.15/1M input tokens versus $2.5/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Gemini 2.5 Flash is ~1567% cheaper at $0.15/1M; pay for GPT-5.4 only for coding workflow support.
Specs
| Released | 2025-06-17 | 2026-03-05 |
| Context window | 1M | — |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-01 | 2025-08 |
Pricing and availability
| Gemini 2.5 Flash | GPT-5.4 | |
|---|---|---|
| Input price | $0.15/1M tokens | $2.5/1M tokens |
| Output price | $0.6/1M tokens | $15/1M tokens |
| Providers |
Capabilities
| Gemini 2.5 Flash | GPT-5.4 | |
|---|---|---|
| Vision | ||
| Multimodal | ||
| Reasoning | ||
| Function calling | ||
| Tool use | ||
| Structured outputs | ||
| Code execution |
Benchmarks
| Benchmark | Gemini 2.5 Flash | GPT-5.4 |
|---|---|---|
| MMLU PRO | 80.9 | 87.5 |
| Massive Multi-discipline Multimodal Understanding | 79.7 | 82.1 |
Deep dive
On shared benchmark coverage, MMLU PRO has Gemini 2.5 Flash at 80.9 and GPT-5.4 at 87.5, with GPT-5.4 ahead by 6.6 points; Massive Multi-discipline Multimodal Understanding has Gemini 2.5 Flash at 79.7 and GPT-5.4 at 82.1, with GPT-5.4 ahead by 2.4 points. The largest visible gap is 6.6 points on MMLU PRO, 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 vision: Gemini 2.5 Flash and reasoning mode: GPT-5.4. Both models share multimodal input, function calling, tool use, 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, Gemini 2.5 Flash lists $0.15/1M input and $0.6/1M output tokens, while GPT-5.4 lists $2.5/1M input and $15/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Gemini 2.5 Flash lower by about $5.96 per million blended tokens. Availability is 4 providers versus 2, so concentration risk also matters.
Choose Gemini 2.5 Flash when coding workflow support, lower input-token cost, and broader provider choice are central to the workload. Choose GPT-5.4 when coding workflow support 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, Gemini 2.5 Flash or GPT-5.4?
Gemini 2.5 Flash is cheaper on tracked token pricing. Gemini 2.5 Flash costs $0.15/1M input and $0.6/1M output tokens. GPT-5.4 costs $2.5/1M input and $15/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Gemini 2.5 Flash or GPT-5.4 open source?
Gemini 2.5 Flash is listed under Proprietary. GPT-5.4 is listed under Proprietary. 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 vision, Gemini 2.5 Flash or GPT-5.4?
Gemini 2.5 Flash has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for multimodal input, Gemini 2.5 Flash or GPT-5.4?
Both Gemini 2.5 Flash and GPT-5.4 expose multimodal input. 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.
Which is better for reasoning mode, Gemini 2.5 Flash or GPT-5.4?
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.
Where can I run Gemini 2.5 Flash and GPT-5.4?
Gemini 2.5 Flash is available on Google AI Studio, GCP Vertex AI, Replicate API, and OpenRouter. GPT-5.4 is available on OpenAI API and OpenRouter. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-04-24. Data sourced from public model cards and provider documentation.