GPT-5.4 vs Gemini 3.5 Flash
Side-by-side comparison of pricing, context window, modalities, licensing, and strengths — with practical guidance on which model fits which workload.
| Spec | GPT-5.4 | Gemini 3.5 Flash |
|---|---|---|
| Provider | OpenAI | |
| Context window | 1M tokens | 1M tokens |
| Input price (per 1M tokens) | $2.50 | $1.50 |
| Output price (per 1M tokens) | $15.00 | $9.00 |
| Example workload (10M in + 2M out) | $55.00 / month | $33.00 / month |
| Modalities | text, image, code | text, image, audio, video, code |
| Knowledge cutoff | Not disclosed | Not disclosed |
| Release date | 2026 | 2026 |
| License | Proprietary | Proprietary |
| Strengths | Coding, Tool search, Structured output, Price-performance | Agentic coding, Speed, Long context, Value |
| Open weights | No | No |
Verdict
Two different answers to “fast and affordable”. Gemini 3.5 Flash is cheaper ($1.50/$9 vs $2.50/$15) and accepts video and audio, making it the multimodal-value pick. GPT-5.4 is the stronger reasoner and coder of the pair and brings tool search — efficient use of large tool libraries — plus OpenAI’s structured-output stack. Both offer roughly 1M-token contexts, though GPT-5.4 bills long prompts (>272K tokens) at double input rates.
When to choose GPT-5.4
Pick GPT-5.4 for harder reasoning and coding, apps with many tools, and strict structured outputs.
When to choose Gemini 3.5 Flash
Pick Gemini 3.5 Flash for video/audio pipelines, long-context summarisation at flat pricing, and lower cost overall.
Prices and specs reflect published provider information and change frequently — always confirm on the provider's pricing page before committing to a workload.
About
This page compares GPT-5.4 (OpenAI) and Gemini 3.5 Flash (Google) side by side across the specs that actually drive a model decision: API pricing per million tokens, context window size, supported modalities, licensing and open-weights status, knowledge cutoff, and headline strengths. A worked example projects the monthly cost of a typical workload (10M input + 2M output tokens) on each model, and an editorial verdict summarises when to choose which. Spec data comes from the same registry that powers our full model comparison table, so figures stay consistent across the site.
How to use
- 1 Scan the spec table for the head-to-head numbers — pricing, context window, modalities, license, and strengths for GPT-5.4 and Gemini 3.5 Flash.
- 2 Check the example-workload row to see what a realistic monthly volume costs on each model.
- 3 Read the verdict and the two "when to choose" cards to map each model to your use case.
- 4 Use the FAQ for quick answers on price, context window, and self-hosting.
- 5 Estimate your own numbers with the AI cost calculator and token counter linked at the bottom, or jump to a related comparison.
- Which is cheaper: GPT-5.4 or Gemini 3.5 Flash?
- Gemini 3.5 Flash is cheaper per token: $1.50 input / $9.00 output per 1M tokens, versus $2.50 / $15.00 for GPT-5.4. Actual costs depend on your input-to-output ratio — try the AI cost calculator for your own numbers.
- Which has the larger context window?
- Both models offer roughly the same 1M-token context window, so raw capacity won't be the deciding factor — check instead whether either provider charges premium rates for long prompts.
- Can I self-host either model?
- No — both models are proprietary and available only through their providers' APIs or cloud platforms.
- How should I test which model is better for my use case?
- Benchmarks are a starting point, not an answer. Run both models on 20–50 examples of your real task and compare outputs blind. Use our token counter to estimate prompt sizes and the cost calculator to project monthly spend before committing.
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