Gemini 3.5 Flash vs GPT-5.1
Wins 6 of 7 areas
Coding · Agents · Reasoning · Facts · Images and charts · Following instructions
Wins 1 of 7 areas
Long documents
Gemini 3.5 Flash is the stronger all-rounder.GPT-5.1 is better at long documents.
Scores updated · 27 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.
- ReasoningHard problems that need careful thinking50Gemini 3.5 Flash5 of 5 tests
- CodingWriting and fixing software31Gemini 3.5 Flash3 of 4 tests
- AgentsCarrying out multi-step tasks on its own20Gemini 3.5 Flash2 of 2 tests
- Images and chartsUnderstanding pictures, charts and video20Gemini 3.5 Flash2 of 2 tests
- FactsGetting facts right instead of making them up21Gemini 3.5 Flash2 of 3 tests
- Following instructionsDoing exactly what it is asked10Gemini 3.5 Flash1 of 1 test
- Long documentsFinding answers in very long texts01GPT-5.11 of 1 test
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 3.5 Flash costs 7% less for the same work.
The biggest differences
The three tests each model wins by the widest margin. Scores are out of 100.
Where Gemini 3.5 Flash pulls ahead
- Abstract visual puzzles that people can solveARC-AGI-2+54.5points ahead
- Command-line tasks in a real terminalTerminal-Bench 2.1+26.3points ahead
- Common-sense trick questionsSimpleBench+23.5points ahead
Where GPT-5.1 pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+10.3points ahead
- Reasons across sets of long documentsAA-LCR+6.7points ahead
- Hard command-line tasks in a real terminalTerminal-Bench Hard+4.6points ahead
Every test, side by side
All 27 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingGemini 3.5 Flash
- Terminal-Bench 2.1Gemini 3.5 Flash by 26.378.752.4+26.3
- SciCodeGemini 3.5 Flash by 10.653.943.3+10.6
- LMArena · WebDevGemini 3.5 Flash by 104 rating points14991395+104 rating
- Terminal-Bench HardGPT-5.1 by 4.640.945.5+4.6
AgentsGemini 3.5 Flash
- GDPValGemini 3.5 Flash by 18.735.216.5+18.7
- τ-Bench V3 · BankingGemini 3.5 Flash by 16.332.215.9+16.3
ReasoningGemini 3.5 Flash
- ARC-AGI-2Gemini 3.5 Flash by 54.572.117.6+54.5
- SimpleBenchGemini 3.5 Flash by 23.576.753.2+23.5
- Humanity's Last ExamGemini 3.5 Flash by 14.242.728.5+14.2
- CritPtGemini 3.5 Flash by 8.213.14.9+8.2
- GPQA DiamondGemini 3.5 Flash by 4.992.287.3+4.9
FactsGemini 3.5 Flash
- SimpleQA VerifiedGemini 3.5 Flash by 18.266.248+18.2
- AA-Omniscience · AccuracyGemini 3.5 Flash by 13.751.437.7+13.7
- AA-Omniscience · Non-hallucinationGPT-5.1 by 10.337.848.1+10.3
Images and chartsGemini 3.5 Flash
- MMMU-ProGemini 3.5 Flash by 8.884.375.5+8.8
- LMArena · VisionGemini 3.5 Flash by 60 rating points13101250+60 rating
Following instructionsGemini 3.5 Flash
- IFBenchGemini 3.5 Flash by 3.476.372.9+3.4
Other results9 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.
- Terminal-Bench 2.0Gemini 3.5 Flash by 28.676.247.6+28.6
- Artificial Analysis Coding IndexGemini 3.5 Flash by 20.770.149.4+20.7
- ARC-AGI-1Gemini 3.5 Flash by 19.792.572.8+19.7
- AA-OmniscienceGemini 3.5 Flash by 15.821.25.4+15.8
- τ²-Bench Telecom (AA run)Gemini 3.5 Flash by 13.495.381.9+13.4
- matharena_visual_math_overallGemini 3.5 Flash by 1389.976.9+13
- AA IntelligenceGemini 3.5 Flash by 7.932.624.7+7.9
- AA Agentic IndexGemini 3.5 Flash by 5.727.321.6+5.7
- frontiermath_tier_4_v1Gemini 3.5 Flash by 2.114.612.5+2.1
Questions people ask
Which is better, Gemini 3.5 Flash or GPT-5.1?
Gemini 3.5 Flash wins six of the seven areas where both have results: coding, agents, reasoning, facts, images and charts and following instructions. GPT-5.1 wins long documents.
Which is better for coding?
Gemini 3.5 Flash. It wins 3 of the 4 coding tests both models report; GPT-5.1 wins 1.
Which is cheaper?
Gemini 3.5 Flash costs $1.50 per million input tokens and $9.00 per million output tokens; GPT-5.1 costs $1.25 and $10.00. That makes Gemini 3.5 Flash about 7% cheaper for the same work.
How do you compare the two?
We use the 27 benchmark tests both models have published scores on. The verdict counts the 18 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 9 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.