GPT-5.4 mini vs Gemini 3.5 Flash: cost

For a typical support chatbot, GPT-5.4 mini is about 2.4× cheaper than Gemini 3.5 Flash ($332 vs $810 per month). Price is only one factor: test both on your own prompts before switching.

GPT-5.4 mini vs Gemini 3.5 Flash: prices and limits
GPT-5.4 miniGemini 3.5 Flash
Input /1M$0.75$1.50
Output /1M$4.50$9.00
Cached input /1M$0.075$0.15
Batch input /1M$0.375$0.75
Batch output /1M$2.25$4.50
Context window400,0001,048,576
Max input272,0001,048,576
Max output128,00065,536

Monthly cost by workload

Estimated monthly cost by workload (USD)
Scenario (per month)GPT-5.4 miniGemini 3.5 Flash
Customer support chatbot
5,000 req/day · 1,200 in · 400 out · cache 60%		$332$810
RAG over documents
2,000 req/day · 8,000 in · 600 out · cache 30%		$425$850
Coding agent
1,500 req/day · 25,000 in · 2,000 out · cache 80%		$641$1,282
Deep reasoning
800 req/day · 3,000 in · 6,000 out · cache 20%		$692$1,404
Batch processing
50,000 req/day · 1,500 in · 150 out · batch		$1,350$2,700