Noometry

Model comparison

Claude Opus 5.5 vs GPT-5.3 Chat

Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 42.8 on the Noometry Index. GPT-5.3 Chat costs 1.7× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.

Last verified . 15 shared benchmarks.

Claude Opus 5.5 Anthropic

68.6

Rank #3 Confirmed

GPT-5.3 Chat OpenAI

42.8

Rank #109 Confirmed

Summary

  • They share 15 benchmarks with published results for both. Claude Opus 5.5 scores higher in 8 categories and GPT-5.3 Chat in 0 categories; 8 gaps are clear of the uncertainty.
  • The widest gap is in math, where Claude Opus 5.5 leads 91.8 to 38.2.
  • GPT-5.3 Chat is cheaper at $1.75 / $14 per million input/output tokens, against $4 / $20 for Claude Opus 5.5.
  • Claude Opus 5.5 accepts more context: 1M tokens versus 128K.

Side by side

Claude Opus 5.5GPT-5.3 Chat
ProviderAnthropicOpenAI
Noometry Index68.642.8
Released2026-09-222026-03-03
WeightsProprietaryProprietary
Context window1M128K
Max output128K16K
Input $ / M tokens$4$1.75
Output $ / M tokens$20$14
Results tracked4418

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Category by category

Coding Claude Opus 5.5 leads

Claude Opus 5.5: 71.9 (#3), GPT-5.3 Chat: 41.4 (#124)

BenchmarkClaude Opus 5.5GPT-5.3 Chat
LMArena Coding15471408
FrontierCode54.6%—
CursorBench57.8%—
LMArena WebDev1813—
FrontierSWE62.3%—
SciCode66.9%—
MirrorCode77.4%—
ALE-Bench2,147—

Agentic & Tool Use Not comparable

Claude Opus 5.5: 45.3 (#15), GPT-5.3 Chat: —

BenchmarkClaude Opus 5.5GPT-5.3 Chat
APEX-Agents73.5%—
GDP.pdf30.6%—
Vending-Bench 29,235—

Reasoning Claude Opus 5.5 leads

Claude Opus 5.5: 80.2 (#3), GPT-5.3 Chat: 28.5 (#102)

BenchmarkClaude Opus 5.5GPT-5.3 Chat
LMArena Hard Prompts15351399
ARC-AGI-293.3%—
NYT Connections (extended)88.5%—
ARC-AGI-198.5%—
CritPt31.7%—
EBR-Bench71.4%—
Mystery Game Puzzles71%—
DTBench98.9%—
LMCA68.2%—
Epoch Capabilities Index167.33—

Math Claude Opus 5.5 leads

Claude Opus 5.5: 91.8 (#3), GPT-5.3 Chat: 38.2 (#142)

BenchmarkClaude Opus 5.5GPT-5.3 Chat
LMArena Math15061389
FrontierMath (Tiers 1-3)91.2%—
FrontierMath Tier 495%—
OTIS Mock AIME 2024-2025100%—
ProofBench100%—
FrontierMath Erdős2.9%—

Knowledge Claude Opus 5.5 leads

Claude Opus 5.5: 66.4 (#10), GPT-5.3 Chat: 38.8 (#140)

BenchmarkClaude Opus 5.5GPT-5.3 Chat
LMArena Expert15471397
GPQA Diamond90.6%—
SimpleQA Verified72.2%—

Multimodal Not comparable

Claude Opus 5.5: 57.8 (#1), GPT-5.3 Chat: —

BenchmarkClaude Opus 5.5GPT-5.3 Chat
LMArena Vision1321—
Blueprint-Bench 251.2%—
Furniture Assembly83.3%—

Multilingual Claude Opus 5.5 leads

Claude Opus 5.5: 59.1 (#2), GPT-5.3 Chat: 50.3 (#124)

BenchmarkClaude Opus 5.5GPT-5.3 Chat
LMArena Non-English15071382
LMArena Chinese15881432
LMArena French15141397
LMArena Russian15201400
LMArena Spanish15071371
LMArena German—1384
LMArena Japanese—1352
LMArena Korean—1346

Instruction Following Claude Opus 5.5 leads

Claude Opus 5.5: 80.0 (#3), GPT-5.3 Chat: 72.8 (#129)

BenchmarkClaude Opus 5.5GPT-5.3 Chat
LMArena Instruction Following15371378

Long Context Claude Opus 5.5 leads

Claude Opus 5.5: 47.1 (#19), GPT-5.3 Chat: 42.6 (#120)

BenchmarkClaude Opus 5.5GPT-5.3 Chat
LMArena Longer Query15321396

Writing & Preference Claude Opus 5.5 leads

Claude Opus 5.5: 78.2 (#3), GPT-5.3 Chat: 63.1 (#68)

BenchmarkClaude Opus 5.5GPT-5.3 Chat
LMArena Text15151389
LMArena Creative Writing15331355
EQ-Bench Creative Writing20501690
LMArena Multi-Turn14991412

Frequently asked questions

Is Claude Opus 5.5 better than GPT-5.3 Chat?

Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 42.8 on the Noometry Index. GPT-5.3 Chat costs 1.7× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.

Which is cheaper, Claude Opus 5.5 or GPT-5.3 Chat?

GPT-5.3 Chat is cheaper. It lists at $1.75 per million input tokens and $14 per million output tokens; Claude Opus 5.5 lists at $4 and $20.

Is Claude Opus 5.5 or GPT-5.3 Chat better for coding?

Claude Opus 5.5 scores higher on coding benchmarks: 71.9 versus 41.4 in the Noometry coding category.

Which has the bigger context window?

Claude Opus 5.5 does, with 1M tokens against 128K.

How many benchmarks do Claude Opus 5.5 and GPT-5.3 Chat share?

15 benchmarks have published results for both models. Claude Opus 5.5 has 44 scored results on Noometry and GPT-5.3 Chat has 18.

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