Gemini 2.5 Flash vs GPT-5 Nano: Detailed Comparison
Choosing between Gemini 2.5 Flash (Google) and
GPT-5 Nano (OpenAI) comes down to three things:
per-token pricing, context window, and which capability matters most for your workload.
Gemini 2.5 Flash costs $0.30/M input vs
$0.05/M for GPT-5 Nano;
context windows are 1.0M vs
400K tokens. Detailed breakdown below.
Side-by-side specs
| Spec | Gemini 2.5 Flash | GPT-5 Nano |
|---|
| Provider | Google | OpenAI |
|---|
| Released | 2025-04-09 | 2025-08-07 |
|---|
| Input price |
$0.30/M |
$0.05/M |
| Output price |
$2.50/M |
$0.40/M |
| Cached input |
$0.0750/M |
$0.0050/M |
| Context window |
1.0M |
400K |
| Max output |
66K |
64K |
| Modalities |
text image audio video |
text |
| Tokenizer |
gemini |
o200k_base |
Capability matrix
| Capability | Gemini 2.5 Flash | GPT-5 Nano |
|---|
| function calling |
Yes |
Yes |
| json mode |
Yes |
Yes |
| vision |
Yes |
No |
| streaming |
Yes |
Yes |
| audio |
Yes |
No |
| video |
Yes |
No |
Per-call cost on typical workloads
| Workload (in/out tokens) | Gemini 2.5 Flash | GPT-5 Nano | Cheaper by |
|---|
| Standard chat (1K / 500) |
$0.001550 |
$0.000250 |
GPT-5 Nano by $0.001300 |
| RAG (4K / 500) |
$0.002450 |
$0.000400 |
GPT-5 Nano by $0.002050 |
| Long doc (20K / 1K) |
$0.008500 |
$0.001400 |
GPT-5 Nano by $0.007100 |
| Very long context (100K / 2K) |
$0.033750 |
$0.005600 |
GPT-5 Nano by $0.028150 |
When to choose Gemini 2.5 Flash over GPT-5 Nano
- Larger context window (1.0M vs 400K) — relevant when whole documents or long histories must fit in a single call.
- Supports vision — GPT-5 Nano does not.
- Supports audio — GPT-5 Nano does not.
- Supports video — GPT-5 Nano does not.
When to choose GPT-5 Nano over Gemini 2.5 Flash
- Per-token input cost is 83% lower than Gemini 2.5 Flash.
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