Gemini 3.5 Flash vs GPT-5.4: fast utility vs frontier flagship pricing
Gemini 3.5 Flash is 5x cheaper. Use it for lightweight utility work. Upgrade to GPT-5.4 when you need complex reasoning, planning, or code synthesis.
Utility cost versus premium flagship performance.
Choosing between a lightweight fast model and a fully capable intelligence model requires analyzing your API bill. Here is how Gemini 3.5 Flash and GPT-5.4 stack up.
By TechCompare · Updated
Cost Comparison
Based on 100,000 input tokens (50% cached), 5,000 output tokens, and 100 requests.
Side-by-side specs
| Spec | Gemini 3.5 Flash | GPT-5.4 |
|---|---|---|
| Input Cost (per M) | $0.50 (better on this spec) | $2.50 |
| Output Cost (per M) | $3.00 (better on this spec) | $15.00 |
| Cached Input (per M) | $0.25 | $0.25 |
| Batch Discount | 50% | 50% |
How they differ
Gemini 3.5 Flash costs $0.50 per million input tokens and $3.00 per million output tokens. GPT-5.4 is priced at $2.50 per million input tokens and $15.00 per million output tokens.
Verdict
Flash runs $0.50/M input and $3.00/M output against GPT-5.4's $2.50 and $15.00, a clean 5x gap on both rows. Cached input ties at $0.25/M and batch ties at 50%, so neither discount disturbs the base ranking. The honest framing is tier difference: Flash is the utility layer, GPT-5.4 the intelligence layer. A common play is to route through Flash and only escalate the cases that genuinely need frontier reasoning.
Which should you pick?
Choose Gemini 3.5 Flash
High-volume classification, basic search filtering, and low-latency runs.
Choose GPT-5.4
Advanced logical reasoning, data synthesis, and deep research tasks.