GPT-5 vs Gemini 2.5 Flash
Detailed pricing comparison and cost analysis.
Updated March 2026
Cost Simulator
| Feature | GPT-5 | Gemini 2.5 Flash |
|---|---|---|
| Provider | OpenAI | |
| Input Price (1M) | $1.25 | $0.30 |
| Output Price (1M) | $10.00 | $2.50 |
| Context Window | 400,000 | 1,000,000 |
Verdict
GPT-5 costs $1.25 per 1M input tokens and $10.00 per 1M output tokens. Gemini 2.5 Flash costs $0.30 per 1M input tokens and $2.50 per 1M output tokens. Gemini 2.5 Flash is 76% cheaper on input tokens than GPT-5. For output tokens, Gemini 2.5 Flash is the more affordable option at $2.50/1M vs $10.00.
On context window, Gemini 2.5 Flash supports 1,000,000 tokens — meaning it can fit more conversation history, documents, or code in a single request. This matters for RAG pipelines, long document analysis, and agentic workflows where context builds up over many turns.
When to choose GPT-5
- ✓ You are already integrated with OpenAI
When to choose Gemini 2.5 Flash
- ✓ You need the lowest input token cost ($ 0.30/1M)
- ✓ Your workload is output-heavy — Gemini 2.5 Flash generates text cheaper
- ✓ You need a larger context window (1,000,000 tokens)
- ✓ You are already integrated with Google
Use the calculator above to simulate your specific workload and find the exact break-even point. For most applications, the cheapest model is the one that minimises your total monthly bill given your input-to-output token ratio.