Gemini 3 Flash Preview vs GPT-5.1 Codex
Wins 5 of 7 areas
Coding · Reasoning · Images and charts · Long documents · Following instructions
Wins 0 of 7 areas
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Gemini 3 Flash Preview is the stronger all-rounder.
Scores updated · 20 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 software40Gemini 3 Flash Preview4 of 4 tests
- ReasoningHard problems that need careful thinking30Gemini 3 Flash Preview3 of 3 tests
- Images and chartsUnderstanding pictures, charts and video10Gemini 3 Flash Preview1 of 1 test
- Long documentsFinding answers in very long texts10Gemini 3 Flash Preview1 of 1 test
- Following instructionsDoing exactly what it is asked10Gemini 3 Flash Preview1 of 1 test
- AgentsCarrying out multi-step tasks on its own00Even0 each · 1 tie
- 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.
Gemini 3 Flash Preview costs 69% 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 Flash Preview pulls ahead
- Answers hard knowledge questions correctlyAA-Omniscience · Accuracy+13.5points ahead
- Very hard expert questions across many subjectsHumanity's Last Exam+10.9points ahead
- Code for real scientific research problemsSciCode+10.4points ahead
Where GPT-5.1 Codex pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+15.8points ahead
Every test, side by side
All 20 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingGemini 3 Flash Preview
- SciCodeGemini 3 Flash Preview by 10.450.640.2+10.4
- LMArena · WebDevGemini 3 Flash Preview by 103 rating points14391336+103 rating
- SWE-bench VerifiedGemini 3 Flash Preview by 4.37873.7+4.3
- Terminal-Bench HardGemini 3 Flash Preview by 3.838.634.8+3.8
ReasoningGemini 3 Flash Preview
- Humanity's Last ExamGemini 3 Flash Preview by 10.936.625.7+10.9
- GPQA DiamondGemini 3 Flash Preview by 3.889.886+3.8
- CritPtGemini 3 Flash Preview by 2.98.65.7+2.9
FactsEven
- AA-Omniscience · Non-hallucinationGPT-5.1 Codex by 15.8722.8+15.8
- AA-Omniscience · AccuracyGemini 3 Flash Preview by 13.553.439.9+13.5
Images and chartsGemini 3 Flash Preview
- MMMU-ProGemini 3 Flash Preview by 7.479.972.5+7.4
Long documentsGemini 3 Flash Preview
- AA-LCRGemini 3 Flash Preview by 8.77869.3+8.7
Following instructionsGemini 3 Flash Preview
- IFBenchGemini 3 Flash Preview by 87870+8
Other results7 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.
- AA-OmniscienceGemini 3 Flash Preview by 16.610.1-6.5+16.6
- swe_bench_bashGemini 3 Flash Preview by 9.875.866+9.8
- Artificial Analysis Coding IndexGemini 3 Flash Preview by 642.636.6+6
- Terminal-Bench 2.0GPT-5.1 Codex by 5.247.652.8+5.2
- AA IntelligenceGemini 3 Flash Preview by 2.626.323.7+2.6
- τ²-Bench Telecom (AA run)GPT-5.1 Codex by 2.680.483+2.6
- AA Agentic IndexGPT-5.1 Codex by 149.750.7+1
Questions people ask
Which is better, Gemini 3 Flash Preview or GPT-5.1 Codex?
Gemini 3 Flash Preview wins five of the seven areas where both have results: coding, reasoning, images and charts, long documents and following instructions. GPT-5.1 Codex wins none. They are level on agents and facts.
Which is better for coding?
Gemini 3 Flash Preview. It wins 4 of the 4 coding tests both models report; GPT-5.1 Codex wins none.
Which is cheaper?
Gemini 3 Flash Preview costs $0.50 per million input tokens and $3.00 per million output tokens; GPT-5.1 Codex costs $1.25 and $10.00. That makes Gemini 3 Flash Preview about 69% cheaper for the same work.
How do you compare the two?
We use the 20 benchmark tests both models have published scores on. The verdict counts the 13 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 7 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.