LLMBenchmark.ai

Enter opens the highlighted result. Esc closes.

GPT-5.1 vs gpt-oss-120b

Updated October 21, 2026. 68 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace GPT-5.1 Replace gpt-oss-120b
GPT-5.1OpenAI
Coding
53.3
Overall
24.7
Output $/M
$10.00
66
gpt-oss-120bOpenAI
Coding
34.5
Overall
11.6
Output $/M
$0.60
2
vs boards won of 68 shared

Decision reading

Pick GPT-5.1 for coding: it scores 53.3 on the Vibe Coding Index against 34.5 for gpt-oss-120b.

Pick gpt-oss-120b when output tokens cost 16.7x less, or when a solved task costs $0.51 against $1.02.

Model AGPT-5.1OpenAI53.3/1002 independent benchmarks$1.02 per solved taskModel Bgpt-oss-120bOpenAI34.5/1002 independent benchmarks$0.51 per solved task
Shared results
68
GPT-5.1 only
32
gpt-oss-120b only
10
Like-for-like categories
8 of 9

Shared results can support a head-to-head reading. Results only one model has describe coverage, not superiority.

Which one for your work

Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.

At a glance

Coding index
GPT-5.1 53.3 from 2 benchmarks, gpt-oss-120b 34.5 from 2 benchmarks.
Widest category
Web design, 25.6 points apart on average over 6 shared benchmarks.
Widest single gap
SWE-bench Verified: GPT-5.1 66.0% against gpt-oss-120b 26.0%, 40.0 points apart on a 0 to 100 scale.
Output price
GPT-5.1 $10.00 against gpt-oss-120b $0.60 per million output tokens, 16.7x apart.
Context window
GPT-5.1 takes 400K tokens, gpt-oss-120b 131K.

Benchmark by benchmark

First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.

Boards won, where both have a result
CategoryGPT-5.1Barsgpt-oss-120bTies
Coding91
Intelligence20
Agentic work20
Reasoning90
Math61
Knowledge110
Web design60
General210
All shared boards662
CodingLike-for-likeFour of these boards feed the Vibe Coding Index91
Coding benchmarks for GPT-5.1 and gpt-oss-120b
BenchmarkGPT-5.1gpt-oss-120bLeader
Aider polyglotNot measured41.8%Only gpt-oss-120b measured
SWE-bench Verified66.0%26.0%GPT-5.1
LMArena WebDev1396Not measuredOnly GPT-5.1 measured
AA Coding Index49.430.4GPT-5.1
LiveCodeBench (Vals AI)86.5%83.2%GPT-5.1
SWE-bench Verified (Vals AI)69.8%33.6%GPT-5.1
Vibe Code Bench (Vals AI)24.6%Not measuredOnly GPT-5.1 measured
LiveCodeBench (Artificial Analysis run)86.8%87.8%gpt-oss-120b
SciCodeNot measured34.0%Only gpt-oss-120b measured
Terminal-Bench Hard (Artificial Analysis run)45.5%23.5%GPT-5.1
Terminal-Bench47.6%18.7%GPT-5.1
GSO-Bench13.7%Not measuredOnly GPT-5.1 measured
WeirdML60.8%48.2%GPT-5.1
ALE-BenchNot measured575.6Only gpt-oss-120b measured
LMArena Text: coding14531379GPT-5.1
LMArena Text: software and IT14541387GPT-5.1
LMArena WebDev: React1307Not measuredOnly GPT-5.1 measured
LMArena WebDev: HTML1405Not measuredOnly GPT-5.1 measured
LMArena WebDev: from an image1421Not measuredOnly GPT-5.1 measured
Neither model has a result on the other 19 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for GPT-5.1 and gpt-oss-120b
BenchmarkGPT-5.1gpt-oss-120bLeader
AA Intelligence Index24.711.6GPT-5.1
Epoch Capabilities Index149.8139.8GPT-5.1
Agentic workLike-for-likePublic boards, shown as published, kept out of the index20
Agentic work benchmarks for GPT-5.1 and gpt-oss-120b
BenchmarkGPT-5.1gpt-oss-120bLeader
AA Agentic IndexNot measured3.7Only gpt-oss-120b measured
τ²-Bench Telecom81.9%65.8%GPT-5.1
APEX-AgentsNot measured4.4%Only gpt-oss-120b measured
METR time horizonsNot measured56.6%Only gpt-oss-120b measured
DeepResearch Bench42.8%Not measuredOnly GPT-5.1 measured
Vending-Bench 2$1,473-$22GPT-5.1
Neither model has a result on the other 33 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index90
Reasoning benchmarks for GPT-5.1 and gpt-oss-120b
BenchmarkGPT-5.1gpt-oss-120bLeader
GPQA Diamond86.6%78.5%GPT-5.1
MMMU Pro (Vals AI)83.2%Not measuredOnly GPT-5.1 measured
GPQA Diamond (Artificial Analysis run)87.3%78.2%GPT-5.1
Humanity's Last Exam (Artificial Analysis run)28.5%19.6%GPT-5.1
GPQA Diamond (Epoch AI run)87.6%75.8%GPT-5.1
ARC-AGI72.8%Not measuredOnly GPT-5.1 measured
ARC-AGI-217.6%Not measuredOnly GPT-5.1 measured
SimpleBench53.2%22.1%GPT-5.1
Chess puzzles42.0%Not measuredOnly GPT-5.1 measured
Mystery game puzzles19.0%2.0%GPT-5.1
VPCT58.7%Not measuredOnly GPT-5.1 measured
LMArena Text: hard prompts14571364GPT-5.1
LMArena Text: expert14701356GPT-5.1
LMArena Text: hard prompts in English14621368GPT-5.1
LMArena Vision: diagrams1264Not measuredOnly GPT-5.1 measured
LMArena Vision: homework1272Not measuredOnly GPT-5.1 measured
Neither model has a result on the other 5 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index61
Math benchmarks for GPT-5.1 and gpt-oss-120b
BenchmarkGPT-5.1gpt-oss-120bLeader
AIME93.3%92.6%GPT-5.1
MATH 500 (Vals AI)Not measured94.8%Only gpt-oss-120b measured
MGSM (Vals AI)93.0%92.0%GPT-5.1
AA Math Index94.093.4GPT-5.1
AIME 2025 (Artificial Analysis run)94.0%93.4%GPT-5.1
OTIS Mock AIME88.6%88.9%gpt-oss-120b
LMArena Text: math14461389GPT-5.1
LMArena Text: mathematical work14491386GPT-5.1
Neither model has a result on the other 5 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index110
Knowledge benchmarks for GPT-5.1 and gpt-oss-120b
BenchmarkGPT-5.1gpt-oss-120bLeader
MMLU Pro86.4%79.2%GPT-5.1
LegalBench (Vals AI)85.7%75.9%GPT-5.1
CaseLaw (Vals AI)73.4%48.8%GPT-5.1
CorpFin (Vals AI)63.8%58.2%GPT-5.1
TaxEval (Vals AI)74.9%71.6%GPT-5.1
MortgageTax (Vals AI)61.4%Not measuredOnly GPT-5.1 measured
MedQA (Vals AI)96.4%91.4%GPT-5.1
MedCode (Vals AI)52.7%Not measuredOnly GPT-5.1 measured
MMLU Pro (Artificial Analysis run)87.0%80.8%GPT-5.1
SimpleQA Verified48.0%Not measuredOnly GPT-5.1 measured
LMArena Text: science14591382GPT-5.1
LMArena Text: medicine and healthcare14561388GPT-5.1
LMArena Text: legal and government14591355GPT-5.1
LMArena Text: business and finance14311359GPT-5.1
Neither model has a result on the other 3 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index60
Web design benchmarks for GPT-5.1 and gpt-oss-120b
BenchmarkGPT-5.1gpt-oss-120bLeader
Design Arena: websites1187968GPT-5.1
Design Arena: UI components1166927GPT-5.1
Design Arena: game dev1179992GPT-5.1
Design Arena: data viz1204987GPT-5.1
Design Arena: 3D1061901GPT-5.1
Design Arena: all code categories1171963GPT-5.1
Design Arena: SVG1149Not measuredOnly GPT-5.1 measured
Design Arena: ASCII art1118Not measuredOnly GPT-5.1 measured
Neither model has a result on the other 1 board here
GeneralLike-for-likePublic boards, shown as published, kept out of the index210
General benchmarks for GPT-5.1 and gpt-oss-120b
BenchmarkGPT-5.1gpt-oss-120bLeader
SAGE (Vals AI)43.2%Not measuredOnly GPT-5.1 measured
MedScribe (Vals AI)88.1%Not measuredOnly GPT-5.1 measured
IFBench72.9%69.0%GPT-5.1
Long context reasoning (AA-LCR)80.0%52.0%GPT-5.1
DTBench90.1%76.3%GPT-5.1
LMCA43.9%22.1%GPT-5.1
Fiction.LiveBenchNot measured44.4%Only gpt-oss-120b measured
Creative writing (Lech Mazur)Not measured77.1%Only gpt-oss-120b measured
CL-bench23.7%Not measuredOnly GPT-5.1 measured
Surface Evolver BenchNot measured25.0%Only gpt-oss-120b measured
CL-bench Life17.3%Not measuredOnly GPT-5.1 measured
LMArena Text14431366GPT-5.1
LMArena Text: instruction following14431318GPT-5.1
LMArena Text: creative writing14271274GPT-5.1
LMArena Vision1250Not measuredOnly GPT-5.1 measured
LMArena Text: English14511375GPT-5.1
LMArena Text: non-English14311351GPT-5.1
LMArena Text: Chinese14951385GPT-5.1
LMArena Text: German14381353GPT-5.1
LMArena Text: Japanese14531331GPT-5.1
LMArena Text: Korean14011282GPT-5.1
LMArena Text: French14501370GPT-5.1
LMArena Text: Spanish14331389GPT-5.1
LMArena Text: Russian14351343GPT-5.1
LMArena Text: Polish14401353GPT-5.1
LMArena Text: multi-turn14501340GPT-5.1
LMArena Text: longer queries14481319GPT-5.1
LMArena Text: writing and language14281306GPT-5.1
LMArena Text: entertainment and media14151292GPT-5.1
LMArena Vision: English1252Not measuredOnly GPT-5.1 measured
LMArena Vision: Chinese1270Not measuredOnly GPT-5.1 measured
LMArena Vision: reading text1255Not measuredOnly GPT-5.1 measured
LMArena Vision: humor1263Not measuredOnly GPT-5.1 measured
LMArena Vision: captioning1252Not measuredOnly GPT-5.1 measured
LMArena Vision: recognizing things1232Not measuredOnly GPT-5.1 measured
LMArena Vision: creative writing1266Not measuredOnly GPT-5.1 measured
LMArena Document1403Not measuredOnly GPT-5.1 measured
Neither model has a result on the other 9 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for GPT-5.1 and gpt-oss-120b
BenchmarkGPT-5.1gpt-oss-120bLeader
Neither model has a result on 5 boards here

What each workload costs

Three fixed token mixes at each model's listed price, so per-token rates become a bill.

Chat turn

1K input + 500 output tokens

GPT-5.1$0.0063Fits in one request
gpt-oss-120b$0.0004Fits in one request

gpt-oss-120b costs less

Repository review

50K input + 3K output tokens

GPT-5.1$0.092Fits in one request
gpt-oss-120b$0.0093Fits in one request

gpt-oss-120b costs less

Agent loop

200K input + 10K output tokens

GPT-5.1$0.350Fits in one request
gpt-oss-120b$0.036Exceeds the context window

gpt-oss-120b costs less

Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.

Specification differences

The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.

Specifications of GPT-5.1 and gpt-oss-120b
SpecificationOpenAI GPT-5.1OpenAI gpt-oss-120b
MakerOpenAIOpenAI
WeightsNo public weights listedOpen weights
ReleasedNovember 13, 2025August 5, 2025
Context window400K131K
Input $/Mtok$1.25$0.15
Output $/Mtok$10.00$0.60
Coding index53.334.5
Independent measurements behind it22
Cost per solved task$1.02$0.51
SourceOpenRouter listingOpenRouter listing

Questions

Is GPT-5.1 better than gpt-oss-120b for coding?

Pick GPT-5.1 for coding: it scores 53.3 on the Vibe Coding Index against 34.5 for gpt-oss-120b. Pick gpt-oss-120b when output tokens cost 16.7x less, or when a solved task costs $0.51 against $1.02.

Which is cheaper, GPT-5.1 or gpt-oss-120b?

GPT-5.1 costs $1.25 per million input tokens and $10.00 per million output tokens; gpt-oss-120b costs $0.15 and $0.60. Per solved SWE-bench Verified task, GPT-5.1 costs $1.02 and gpt-oss-120b $0.51.

Which has the bigger context window, GPT-5.1 or gpt-oss-120b?

GPT-5.1, with 400K tokens against 131K.

How many benchmarks is the GPT-5.1 vs gpt-oss-120b comparison based on?

68 benchmarks have a result for both models as of October 21, 2026. GPT-5.1's coding index rests on 2 independent benchmarks and gpt-oss-120b's on 2. Where only one model has a result, the page says so instead of naming a winner.

Compare next

Embed this comparison on your site

Free under CC BY 4.0, while the source link stays visible. Preview the frame · Terms and other embeds

<iframe src="https://llmbenchmark.ai/embed/compare/gpt-5-1-vs-gpt-oss-120b" title="GPT-5.1 vs gpt-oss-120b, LLMBenchmark.ai" width="100%" height="360" style="border:0;max-width:100%" loading="lazy"></iframe>
<p style="font:13px/1.4 sans-serif;margin:6px 0 0">Source: <a href="https://llmbenchmark.ai/compare/gpt-5-1-vs-gpt-oss-120b">LLMBenchmark.ai, GPT-5.1 vs gpt-oss-120b</a></p>