Gemini 3 Pro vs GPT-5.1 Codex mini
Wins 6 of 7 areas
Coding · Agents · Reasoning · Images and charts · Long documents · Following instructions
Wins 0 of 7 areas
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Gemini 3 Pro is the stronger all-rounder.GPT-5.1 Codex mini is cheaper.
Scores updated · 18 tests both models report · How we compare
Where each one wins
Tests won in each of the seven areas where both have results. Each piece is one test, so a longer bar means more evidence; grey means the two scored within a point of each other.
- CodingWriting and fixing software30Gemini 3 Pro3 of 3 tests
- ReasoningHard problems that need careful thinking30Gemini 3 Pro3 of 3 tests
- AgentsCarrying out multi-step tasks on its own10Gemini 3 Pro1 of 1 test
- Images and chartsUnderstanding pictures, charts and video10Gemini 3 Pro1 of 1 test
- Long documentsFinding answers in very long texts10Gemini 3 Pro1 of 1 test
- Following instructionsDoing exactly what it is asked10Gemini 3 Pro1 of 1 test
- FactsGetting facts right instead of making them up11Even1 each
Agents, images and charts, long documents and following instructions rest on a single test each.
What it costs
Prices per million tokens, roughly 750,000 words. The bars show the cost of a million tokens read plus a million written.
GPT-5.1 Codex mini costs 84% less for the same work.
The biggest differences
The tests each model wins by the widest margin, up to three each. Scores are out of 100.
Where Gemini 3 Pro pulls ahead
- Answers hard knowledge questions correctlyAA-Omniscience · Accuracy+32.6points ahead
- Very hard expert questions across many subjectsHumanity's Last Exam+21.2points ahead
- Code for real scientific research problemsSciCode+13.5points ahead
Where GPT-5.1 Codex mini pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+39.9points ahead
Every test, side by side
All 18 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingGemini 3 Pro
- LMArena · WebDevGemini 3 Pro by 197 rating points14401243+197 rating
- SciCodeGemini 3 Pro by 13.556.142.6+13.5
- Terminal-Bench HardGemini 3 Pro by 8.441.733.3+8.4
ReasoningGemini 3 Pro
- Humanity's Last ExamGemini 3 Pro by 21.239.718.5+21.2
- GPQA DiamondGemini 3 Pro by 9.590.881.3+9.5
- CritPtGemini 3 Pro by 9.19.10+9.1
FactsEven
- AA-Omniscience · Non-hallucinationGPT-5.1 Codex mini by 39.98.548.4+39.9
- AA-Omniscience · AccuracyGemini 3 Pro by 32.655.823.2+32.6
Following instructionsGemini 3 Pro
- IFBenchGemini 3 Pro by 2.570.467.9+2.5
Other results6 tests, not counted
Tests outside the eight areas. They are not counted above: several are summary scores built from other tests, or the same test under another name.
- AIME 2025Gemini 3 Pro by 57.910042.1+57.9
- AA-OmniscienceGemini 3 Pro by 31.715.3-16.4+31.7
- τ²-Bench Telecom (AA run)Gemini 3 Pro by 24.287.162.9+24.2
- AA Agentic IndexGemini 3 Pro by 13.35238.7+13.3
- Artificial Analysis Coding IndexGemini 3 Pro by 10.146.536.4+10.1
- AA IntelligenceGemini 3 Pro by 7.62820.4+7.6
Questions people ask
Which is better, Gemini 3 Pro or GPT-5.1 Codex mini?
Gemini 3 Pro wins six of the seven areas where both have results: coding, agents, reasoning, images and charts, long documents and following instructions. GPT-5.1 Codex mini wins none, but costs 84% less. They are level on facts.
Which is better for coding?
Gemini 3 Pro. It wins 3 of the 3 coding tests both models report; GPT-5.1 Codex mini wins none.
Which is cheaper?
Gemini 3 Pro costs $2.00 per million input tokens and $12.00 per million output tokens; GPT-5.1 Codex mini costs $0.25 and $2.00. That makes GPT-5.1 Codex mini about 84% cheaper for the same work.
How do you compare the two?
We use the 18 benchmark tests both models have published scores on. The verdict counts the 12 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 6 are listed but not counted, because several are summary scores or repeat a test. Each score is the one shown on the model's own page.