Gemini 3.5 Flash vs GPT-5.4: API Pricing
Input and output token rates, context windows, and real monthly cost for Gemini 3.5 Flash (Google) and GPT-5.4 (OpenAI), side by side. Prices are standard on-demand rates as of June 2026.
The short answer
For a typical coding-agent workload (60M in / 12M out per month), Gemini 3.5 Flash is the cheaper option at $198/mo versus $330/mo for GPT-5.4 - about 40% less (1.7× cheaper). On the headline sticker of 1M input + 1M output, Gemini 3.5 Flash is $10.50 and GPT-5.4 is $17.50.
Rates at a glance
| Gemini 3.5 Flash | GPT-5.4 | |
|---|---|---|
| Input ($/1M tokens) | $1.50 | $2.50 |
| Output ($/1M tokens) | $9.00 | $15.00 |
| Blended (1M in + 1M out) | $10.50 | $17.50 |
| Context window | 1,000K | 1,050K |
| Type | Proprietary | Proprietary |
| Provider | OpenAI |
Monthly cost by workload
Estimated monthly API spend at each workload's token volume. Output usually costs several times input, so the winner can flip with your mix.
| Workload | Gemini 3.5 Flash | GPT-5.4 | Cheaper |
|---|---|---|---|
| Chatbot / assistant 10M in / 3M out | $42.00/mo | $70.00/mo | Gemini 3.5 Flash |
| Coding agent 60M in / 12M out | $198/mo | $330/mo | Gemini 3.5 Flash |
| RAG / summarization 40M in / 4M out | $96.00/mo | $160/mo | Gemini 3.5 Flash |
| Batch / classification 20M in / 2M out | $48.00/mo | $80.00/mo | Gemini 3.5 Flash |
Want your own in/out split? Use the full interactive comparator to rank every model and provider for your exact workload.
Frequently asked questions
Is Gemini 3.5 Flash or GPT-5.4 cheaper?
It depends on your input/output mix, but for a typical coding-agent workload (60M in / 12M out per month) Gemini 3.5 Flash costs $198/mo versus $330/mo for GPT-5.4 - about 40% less (1.7x). On the headline sticker (1M input + 1M output), Gemini 3.5 Flash is $10.50 and GPT-5.4 is $17.50.
What are the token rates for Gemini 3.5 Flash and GPT-5.4?
Gemini 3.5 Flash (Google) is $1.50 per 1M input and $9.00 per 1M output. GPT-5.4 (OpenAI) is $2.50 per 1M input and $15.00 per 1M output. These are standard on-demand rates, not cached or batch.
Is Gemini 3.5 Flash or GPT-5.4 open-weight?
Gemini 3.5 Flash is proprietary and GPT-5.4 is proprietary. Both are closed models billed only through their owner's API.
What context window do Gemini 3.5 Flash and GPT-5.4 support?
Gemini 3.5 Flash supports 1,000K tokens and GPT-5.4 supports 1,050K tokens. Some models also step up pricing past a size threshold - check the source pricing pages for long-context tiers.
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