GPT-5.1 vs Qwen3.5 27B
Wins 5 of 7 areas
Coding · Reasoning · Facts · Images and charts · Long documents
Wins 1 of 7 areas
Agents
GPT-5.1 is the stronger all-rounder.Qwen3.5 27B is cheaper and better at agents.
Scores updated · 32 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 software50GPT-5.15 of 5 tests
- ReasoningHard problems that need careful thinking30GPT-5.13 of 3 tests
- FactsGetting facts right instead of making them up20GPT-5.12 of 3 tests · 1 tie
- Images and chartsUnderstanding pictures, charts and video20GPT-5.12 of 3 tests · 1 tie
- Long documentsFinding answers in very long texts10GPT-5.11 of 1 test
- AgentsCarrying out multi-step tasks on its own02Qwen3.5 27B2 of 2 tests
- Following instructionsDoing exactly what it is asked11Even1 each
Long documents rests on a single test.
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.
Qwen3.5 27B costs 76% less for the same work.
The biggest differences
The three tests each model wins by the widest margin. Scores are out of 100.
Where GPT-5.1 pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+29.6points ahead
- Answers hard knowledge questions correctlyAA-Omniscience · Accuracy+17points ahead
- Hard command-line tasks in a real terminalTerminal-Bench Hard+12.9points ahead
Where Qwen3.5 27B pulls ahead
- Real work tasks from 44 professionsGDPVal+16.5points ahead
- Finds hard-to-locate facts by browsing the webBrowseComp+10.2points ahead
- Follows unfamiliar, precisely checkable instructionsIFBench+2.7points ahead
Every test, side by side
All 32 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingGPT-5.1
- Terminal-Bench HardGPT-5.1 by 12.945.532.6+12.9
- LiveCodeBench v6GPT-5.1 by 6.38780.7+6.3
- SWE-bench VerifiedGPT-5.1 by 3.976.372.4+3.9
- LMArena · WebDevGPT-5.1 by 38 rating points13951357+38 rating
- SciCodeGPT-5.1 by 3.843.339.5+3.8
AgentsQwen3.5 27B
- GDPValQwen3.5 27B by 16.516.533+16.5
- BrowseCompQwen3.5 27B by 10.250.861+10.2
ReasoningGPT-5.1
- Humanity's Last ExamGPT-5.1 by 4.628.523.9+4.6
- CritPtGPT-5.1 by 44.90.9+4
- GPQA DiamondGPT-5.1 by 1.587.385.8+1.5
FactsGPT-5.1
- AA-Omniscience · Non-hallucinationGPT-5.1 by 29.648.118.5+29.6
- AA-Omniscience · AccuracyGPT-5.1 by 1737.720.7+17
- Vectara HHEM hallucination ratelower is bettertie12.112.1tie
Images and chartsGPT-5.1
- MMMUGPT-5.1 by 3.185.482.3+3.1
- LMArena · VisionGPT-5.1 by 10 rating points12501240+10 rating
- MMMU-Protie75.575tie
Following instructionsEven
- IFBenchQwen3.5 27B by 2.772.975.6+2.7
- Multi-ChallengeGPT-5.1 by 2.663.460.8+2.6
Other results13 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-OmniscienceGPT-5.1 by 49.45.4-44+49.4
- AA Agentic IndexQwen3.5 27B by 3321.654.6+33
- vectara_avg_summary_lengthGPT-5.1 by 160 rating points254.494.4+160 rating
- Artificial Analysis Coding IndexGPT-5.1 by 14.549.434.9+14.5
- τ²-Bench Telecom (AA run)Qwen3.5 27B by 1281.993.9+12
- Terminal-Bench 2.0GPT-5.1 by 647.641.6+6
- MMMLUGPT-5.1 by 5.19185.9+5.1
- HMMT Feb. 2025GPT-5.1 by 4.396.392+4.3
- HMMT Nov. 2025GPT-5.1 by 1.991.789.8+1.9
- AA IntelligenceGPT-5.1 by 1.824.722.9+1.8
- MMLU-Protie8786.1tie
- vectara_answer_ratetie10099.8tie
- vectara_factual_consistencytie87.987.9tie
Questions people ask
Which is better, GPT-5.1 or Qwen3.5 27B?
GPT-5.1 wins five of the seven areas where both have results: coding, reasoning, facts, images and charts and long documents. Qwen3.5 27B wins agents, and costs 76% less. They are level on following instructions.
Which is better for coding?
GPT-5.1. It wins 5 of the 5 coding tests both models report; Qwen3.5 27B wins none.
Which is cheaper?
GPT-5.1 costs $1.25 per million input tokens and $10.00 per million output tokens; Qwen3.5 27B costs $0.30 and $2.40. That makes Qwen3.5 27B about 76% cheaper for the same work.
How do you compare the two?
We use the 32 benchmark tests both models have published scores on. The verdict counts the 19 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 13 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.