gpt-5.1 vs gemini-3.5-flash
Side-by-side comparison of gpt-5.1 and gemini-3.5-flash: benchmarks, pricing, context window and capabilities. Both are accessible through Requesty's unified API. gemini-3.5-flash outperforms gpt-5.1 on 6 of 7 shared benchmarks.
gpt-5.1
Input / 1M
$1.25
Output / 1M
$10.00
Context
400K
Model ID
openai/gpt-5.1
gemini-3.5-flash
Input / 1M
$1.50
Output / 1M
$9.00
Context
1.0M
Model ID
vertex/gemini-3.5-flash
Benchmark comparison
Intelligence Indexreasoning
gpt-5.136.9%
gemini-3.5-flash50.2%
Coding Indexcoding
gpt-5.149.4%
gemini-3.5-flash70.1%
Math Indexmath
gpt-5.194.0%
gemini-3.5-flashN/A
GPQA Diamondreasoning
gpt-5.187.3%
gemini-3.5-flash92.2%
AIME 2025math
gpt-5.194.0%
gemini-3.5-flashN/A
LiveCodeBenchcoding
gpt-5.186.8%
gemini-3.5-flashN/A
Terminal-Bench Hardagentic
gpt-5.145.5%
gemini-3.5-flash40.9%
τ²-Benchagentic
gpt-5.181.9%
gemini-3.5-flash95.3%
SciCodecoding
gpt-5.143.3%
gemini-3.5-flash53.1%
MMLU Proknowledge
gpt-5.187.0%
gemini-3.5-flashN/A
Humanity's Last Examreasoning
gpt-5.126.5%
gemini-3.5-flash41.0%
Scores sourced from official model cards, Artificial Analysis, and public leaderboards. Benchmarks measure specific skills and don't capture every aspect of model quality.
Pricing & specifications
| gpt-5.1 | gemini-3.5-flash | |
|---|---|---|
| Input price / 1M | $1.25 | $1.50 |
| Output price / 1M | $10.00 | $9.00 |
| Context window | 400K tokens | 1.0M tokens |
| Max output | 128K tokens | 66K tokens |
| Vision input | Yes | Yes |
| Tool calling | Yes | Yes |
| Reasoning | Yes | Yes |
| Prompt caching | Yes | Yes |
| Computer use | N/A | N/A |
| Provider | OpenAI Inc. | Google LLC (Vertex AI) |
Questions people ask
Is gpt-5.1 better than gemini-3.5-flash?
gemini-3.5-flash outperforms gpt-5.1 on 6 of 7 shared benchmarks. See the benchmark comparison above for specifics: gpt-5.1 and gemini-3.5-flash have different strengths across reasoning, coding, math and multimodal tasks.
Which is cheaper, gpt-5.1 or gemini-3.5-flash?
gemini-3.5-flash is cheaper. gpt-5.1 costs $1.25/$10.00 per 1M input/output tokens, while gemini-3.5-flash costs $1.50/$9.00.
Can I use gpt-5.1 and gemini-3.5-flash through the same API?
Yes. Requesty provides a single OpenAI-compatible API that routes to both. Change just the "model" parameter to switch between "openai/gpt-5.1" and "vertex/gemini-3.5-flash", no other code changes needed.
What are the context windows?
gpt-5.1 supports up to 400K tokens of context. gemini-3.5-flash supports up to 1.0M tokens. Longer context means you can feed larger documents or codebases in a single prompt, though quality often degrades past 128K for most models.
Switch between gpt-5.1 and gemini-3.5-flash with one line of code
Requesty provides a single OpenAI-compatible API for 400+ models. Change the model parameter, not your code.