Head-to-head · frontier vs frontier

Gemini 3 Flash Pro vs o4: which model should you choose?

We compared Gemini 3 Flash Pro and o4 on price, context window and 12 benchmarks. o4 has the stronger average benchmark score; o4 is cheaper on a blended 3:1 basis.

Google DeepMind

Gemini 3 Flash Pro

Gemini 3 Flash Pro is a frontier model from Google DeepMind. It offers a 400,000-token context window, costs $17.71 per million input tokens and $86.50 per million output tokens, and averages 84.8 across the index's benchmark suite.

Input: $17.71 / 1M
Output: $86.50 / 1M
Context: 400,000
Avg score: 84.8
Open weights: No

Full Gemini 3 Flash Pro page

OpenAI

o4

o4 is a frontier model from OpenAI. It offers a 2,000,000-token context window, costs $17.74 per million input tokens and $66.00 per million output tokens, and averages 85.4 across the index's benchmark suite.

Input: $17.74 / 1M
Output: $66.00 / 1M
Context: 2,000,000
Avg score: 85.4
Open weights: No

Full o4 page

Specification comparison

Spec	Gemini 3 Flash Pro	o4	Edge
Input price / 1M	$17.71	$17.74	A
Output price / 1M	$86.50	$66.00	B
Context window	400,000	2,000,000	B
Max output	4,096	8,192	B
Average score	84.8	85.4	B
Arena Elo	1469.2	1469.4	B
Open weights	No	No	Tie

Benchmark comparison

Gemini 3 Flash Pro wins 5, o4 wins 6, and 1 benchmarks are tied. The table shows the modelled score for each model and the gap.

Benchmark	Gemini 3 Flash Pro	o4	Gap	Winner
MMLU-Pro	87.0	85.3	1.7	Gemini 3 Flash Pro
GPQA Diamond	77.7	82.3	4.6	o4
SWE-bench Verified	73.3	74.8	1.5	o4
HumanEval	89.9	89.6	0.3	Gemini 3 Flash Pro
MATH-500	91.8	90.5	1.3	Gemini 3 Flash Pro
AIME 2025	79.9	85.3	5.4	o4
LiveCodeBench	80.2	81.4	1.2	o4
IFEval	92.8	92.8	0.0	Tie
TruthfulQA	86.2	85.0	1.2	Gemini 3 Flash Pro
HellaSwag	90.6	91.0	0.4	o4
MMMU	83.0	80.9	2.1	Gemini 3 Flash Pro
Arena Elo	1469.2	1469.4	0.2	o4

Price analysis

On a blended 3:1 input-to-output basis, Gemini 3 Flash Pro costs about $34.91 per million tokens and o4 costs about $29.80. o4 is roughly 15% cheaper than Gemini 3 Flash Pro. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.

o4 has the larger context window at 2,000,000 tokens, compared with 400,000 for Gemini 3 Flash Pro. That matters for long documents, large codebases and multi-step agent traces.

Verdict

Across 12 shared benchmarks, Gemini 3 Flash Pro wins 5, o4 wins 6, and 1 are tied. On the index average, o4 leads Gemini 3 Flash Pro by 0.6 points (85.4 versus 84.8).

The price picture favours o4. The context picture favours o4. Those two dimensions often matter more than a few benchmark points once a model is good enough for the task.

If you need a single default, start with o4 for quality-sensitive work, and check whether its price holds at your expected volume before committing.

Choose Gemini 3 Flash Pro if

You prefer Google DeepMind's tooling or already use it.

Choose o4 if

You want the higher average benchmark score in this index.
Unit cost matters and you want the cheaper blended price.
You need the larger 2,000,000-token context window.
You need the larger 8,192-token output limit.

FAQ

Is Gemini 3 Flash Pro better than o4?

On the index average, o4 leads Gemini 3 Flash Pro by 0.6 points (85.4 versus 84.8). The better choice depends on price, context and your task. Gemini 3 Flash Pro wins 5 benchmarks, o4 wins 6.

Which is cheaper, Gemini 3 Flash Pro or o4?

o4 is cheaper on a blended 3:1 basis at about $29.80 per million tokens, versus $34.91 for Gemini 3 Flash Pro.

Which has the larger context window?

o4 has the larger context window at 2,000,000 tokens. Gemini 3 Flash Pro has 400,000 tokens.

Are these models open weights?

Gemini 3 Flash Pro is proprietary; o4 is proprietary.

Which should I choose for production?