Noometry

Model comparison

Claude Opus 4.5 vs GPT-5 Nano

Claude Opus 4.5 is the stronger model overall, scoring 50.5 to 33.4 on the Noometry Index. GPT-5 Nano costs 73× less per token, which makes it the better buy when Claude Opus 4.5's lead doesn't matter for your workload.

Last verified . 40 shared benchmarks.

Claude Opus 4.5 Anthropic

50.5

Rank #39 Confirmed

GPT-5 Nano OpenAI

33.4

Rank #234 Confirmed

Summary

  • They share 40 benchmarks with published results for both. Claude Opus 4.5 scores higher in 10 categories and GPT-5 Nano in 0 categories; 9 gaps are clear of the uncertainty.
  • The widest gap is in writing & preference, where Claude Opus 4.5 leads 68.2 to 39.4.
  • The biggest single-benchmark swing is ARC-AGI-1: 80% for Claude Opus 4.5 and 20.7% for GPT-5 Nano.
  • GPT-5 Nano is cheaper at $0.05 / $0.40 per million input/output tokens, against $5 / $25 for Claude Opus 4.5.
  • GPT-5 Nano accepts more context: 400K tokens versus 200K.

Side by side

Claude Opus 4.5GPT-5 Nano
ProviderAnthropicOpenAI
Noometry Index50.533.4
Released2025-11-012025-08-07
WeightsProprietaryProprietary
Context window200K400K
Max output64K128K
Input $ / M tokens$5$0.05
Output $ / M tokens$25$0.40
Results tracked6948

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Category by category

Coding Claude Opus 4.5 leads

Claude Opus 4.5: 55.4 (#21), GPT-5 Nano: 33.3 (#248)

BenchmarkClaude Opus 4.5GPT-5 Nano
SWE-bench Verified (bash only)76.8%34.8%
WeirdML63.7%38.1%
LMArena Coding15041351
ALE-Bench1,025718.67
SWE-bench Verified76.7%—
LMArena WebDev1493—
SWE-bench Multilingual70.7%—
GSO26.5%—
AlgoTune1.77—

Agentic & Tool Use Claude Opus 4.5 leads

Claude Opus 4.5: 47.2 (#11), GPT-5 Nano: 25.6 (#99)

BenchmarkClaude Opus 4.5GPT-5 Nano
Terminal-Bench63.1%21.8%
Berkeley Function Calling Leaderboard77.5%51.5%
GDPval45.5%—
Remote Labor Index3.8%—
τ²-bench Airline84%—
τ²-bench Banking24.7%—
τ²-bench Retail79.6%—
τ²-bench Telecom92.3%—
Cybench82%—
DeepResearch Bench54.8%—
OSWorld66.3%—
BALROG43.5%—
LMArena Search1180—
METR Time Horizons75%—
Vending-Bench 24,967—

Reasoning Claude Opus 4.5 leads

Claude Opus 4.5: 42.5 (#43), GPT-5 Nano: 16.4 (#291)

BenchmarkClaude Opus 4.5GPT-5 Nano
ARC-AGI-237.6%2.6%
Kagi LLM Benchmark80.2%62.2%
ARC-AGI-180%20.7%
Chess Puzzles12%27%
LMArena Hard Prompts14761329
Mystery Game Puzzles22%9%
DTBench89.9%62.7%
LMCA44.5%7.9%
Epoch Capabilities Index150.1139.39
ForecastBench60.759.1
SimpleBench62%—
NYT Connections (extended)52.5%—
EnigmaEval11.9%—
EBR-Bench14.3%—

Math Claude Opus 4.5 leads

Claude Opus 4.5: 38.5 (#85), GPT-5 Nano: 29.1 (#221)

BenchmarkClaude Opus 4.5GPT-5 Nano
FrontierMath (Tiers 1-3)34.4%20%
FrontierMath Tier 44.9%2.4%
OTIS Mock AIME 2024-202586.1%81.1%
ProofBench36%12%
LMArena Math14631318
FrontierMath (Feb 2025 set)20.7%8.3%
FrontierMath Tier 4 (v1)4.2%2.1%
Omni-MATH—54.6%
MATH Level 5—95.2%

Knowledge Claude Opus 4.5 leads

Claude Opus 4.5: 56.4 (#38), GPT-5 Nano: 35.8 (#166)

BenchmarkClaude Opus 4.5GPT-5 Nano
GPQA Diamond86%69.4%
SimpleQA Verified45.7%11.7%
Vectara Hallucination Rate10.9%10.5%
LMArena Expert14881321
Humanity's Last Exam25.2%—
MMLU-Pro—77.8%
GPQA (HELM)—67.9%

Multimodal Too close to call

Claude Opus 4.5: 31.1 (#99), GPT-5 Nano: 30.7 (#102)

BenchmarkClaude Opus 4.5GPT-5 Nano
VPCT40%37.2%
LMArena Vision—1159
GeoBench75%—
Furniture Assembly28.3%—
LMArena Document1462—

Multilingual Claude Opus 4.5 leads

Claude Opus 4.5: 54.5 (#45), GPT-5 Nano: 45.5 (#167)

BenchmarkClaude Opus 4.5GPT-5 Nano
LMArena Non-English14381313
LMArena Chinese14701355
LMArena German14491329
LMArena Korean14241269
LMArena Russian14481296
LMArena Spanish14551360
LMArena French1471—
LMArena Japanese1415—

Instruction Following Claude Opus 4.5 leads

Claude Opus 4.5: 77.7 (#20), GPT-5 Nano: 75.2 (#72)

BenchmarkClaude Opus 4.5GPT-5 Nano
LMArena Instruction Following14781306
IFEval—93.2%

Long Context Claude Opus 4.5 leads

Claude Opus 4.5: 46.4 (#21), GPT-5 Nano: 31.3 (#275)

BenchmarkClaude Opus 4.5GPT-5 Nano
LMArena Longer Query14801313
Fiction.LiveBench—44.4%
CL-bench21.1%—

Writing & Preference Claude Opus 4.5 leads

Claude Opus 4.5: 68.2 (#28), GPT-5 Nano: 39.4 (#244)

BenchmarkClaude Opus 4.5GPT-5 Nano
LMArena Text14511320
LMArena Creative Writing14451250
EQ-Bench Creative Writing1687705
LMArena Multi-Turn14661311
WildBench—80.6%

Frequently asked questions

Is Claude Opus 4.5 better than GPT-5 Nano?

Claude Opus 4.5 is the stronger model overall, scoring 50.5 to 33.4 on the Noometry Index. GPT-5 Nano costs 73× less per token, which makes it the better buy when Claude Opus 4.5's lead doesn't matter for your workload.

Which is cheaper, Claude Opus 4.5 or GPT-5 Nano?

GPT-5 Nano is cheaper. It lists at $0.05 per million input tokens and $0.40 per million output tokens; Claude Opus 4.5 lists at $5 and $25.

Is Claude Opus 4.5 or GPT-5 Nano better for coding?

Claude Opus 4.5 scores higher on coding benchmarks: 55.4 versus 33.3 in the Noometry coding category.

Which has the bigger context window?

GPT-5 Nano does, with 400K tokens against 200K.

How many benchmarks do Claude Opus 4.5 and GPT-5 Nano share?

40 benchmarks have published results for both models. Claude Opus 4.5 has 69 scored results on Noometry and GPT-5 Nano has 48.

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