Noometry

Model comparison

GPT-5.3 Chat vs o3

o3 is the stronger model overall, scoring 47.5 to 42.8 on the Noometry Index.

Last verified . 18 shared benchmarks.

GPT-5.3 Chat OpenAI

42.8

Rank #109 Confirmed

o3 OpenAI

47.5

Rank #61 Confirmed

Summary

  • They share 18 benchmarks with published results for both. GPT-5.3 Chat scores higher in 0 categories and o3 in 8 categories; 6 gaps are clear of the uncertainty.
  • The widest gap is in knowledge, where o3 leads 54.6 to 38.8.
  • o3 is cheaper at $2 / $8 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Chat.
  • o3 accepts more context: 200K tokens versus 128K.

Side by side

GPT-5.3 Chato3
ProviderOpenAIOpenAI
Noometry Index42.847.5
Released2026-03-032025-04-16
WeightsProprietaryProprietary
Context window128K200K
Max output16K100K
Input $ / M tokens$1.75$2
Output $ / M tokens$14$8
Results tracked1863

Sponsored placements are available on pages like this one. Advertise on Noometry

Category by category

Coding o3 leads

GPT-5.3 Chat: 41.4 (#124), o3: 46.8 (#64)

BenchmarkGPT-5.3 Chato3
LMArena Coding14081408
SWE-bench Verified—62.3%
SWE-bench Verified (bash only)—58.4%
Aider Polyglot—81.3%
GSO—8.8%
WeirdML—52.4%
CadEval—74%
ALE-Bench—933.55

Agentic & Tool Use Not comparable

GPT-5.3 Chat: —, o3: 34.5 (#44)

BenchmarkGPT-5.3 Chato3
Berkeley Function Calling Leaderboard—63%
GDPval—30.8%
DeepResearch Bench—45.2%
OSWorld—23%
LMArena Search—1144
METR Time Horizons—65.4%

Reasoning o3 leads

GPT-5.3 Chat: 28.5 (#102), o3: 32.0 (#78)

BenchmarkGPT-5.3 Chato3
LMArena Hard Prompts13991402
ARC-AGI-2—6.5%
SimpleBench—53.1%
Kagi LLM Benchmark—67.6%
ARC-AGI-1—60.8%
CritPt—1.4%
Chess Puzzles—38%
EnigmaEval—13.1%
Mystery Game Puzzles—29%
DTBench—84.8%
LMCA—39.7%
Epoch Capabilities Index—146.86
ForecastBench—62.5

Math o3 leads

GPT-5.3 Chat: 38.2 (#142), o3: 50.2 (#58)

BenchmarkGPT-5.3 Chato3
LMArena Math13891426
FrontierMath (Tiers 1-3)—33.3%
OTIS Mock AIME 2024-2025—84.4%
Omni-MATH—71.4%
MATH Level 5—97.8%
FrontierMath (Feb 2025 set)—18.7%
FrontierMath Tier 4 (v1)—2.1%

Knowledge o3 leads

GPT-5.3 Chat: 38.8 (#140), o3: 54.6 (#52)

BenchmarkGPT-5.3 Chato3
LMArena Expert13971402
GPQA Diamond—81.8%
Humanity's Last Exam—20.3%
SimpleQA Verified—49.4%
MMLU-Pro—85.9%
Confabulations—14.4%
GPQA (HELM)—75.3%

Multimodal Not comparable

GPT-5.3 Chat: —, o3: 41.4 (#36)

BenchmarkGPT-5.3 Chato3
LMArena Vision—1214
GeoBench—74%
VPCT—52%

Multilingual o3 leads

GPT-5.3 Chat: 50.3 (#124), o3: 51.7 (#105)

BenchmarkGPT-5.3 Chato3
LMArena Non-English13821401
LMArena Chinese14321437
LMArena French13971430
LMArena German13841420
LMArena Japanese13521403
LMArena Korean13461370
LMArena Russian14001406
LMArena Spanish13711395

Instruction Following Too close to call

GPT-5.3 Chat: 72.8 (#129), o3: 72.8 (#127)

BenchmarkGPT-5.3 Chato3
LMArena Instruction Following13781368
IFEval—86.9%

Long Context o3 leads

GPT-5.3 Chat: 42.6 (#120), o3: 53.3 (#6)

BenchmarkGPT-5.3 Chato3
LMArena Longer Query13961372
Fiction.LiveBench—88.9%
CL-bench—17.8%

Writing & Preference Too close to call

GPT-5.3 Chat: 63.1 (#68), o3: 63.5 (#64)

BenchmarkGPT-5.3 Chato3
LMArena Text13891410
LMArena Creative Writing13551359
EQ-Bench Creative Writing16901676
LMArena Multi-Turn14121405
Short-Story Creative Writing—83.9%
WildBench—86.1%

Frequently asked questions

Is GPT-5.3 Chat better than o3?

o3 is the stronger model overall, scoring 47.5 to 42.8 on the Noometry Index.

Which is cheaper, GPT-5.3 Chat or o3?

o3 is cheaper. It lists at $2 per million input tokens and $8 per million output tokens; GPT-5.3 Chat lists at $1.75 and $14.

Is GPT-5.3 Chat or o3 better for coding?

o3 scores higher on coding benchmarks: 46.8 versus 41.4 in the Noometry coding category.

Which has the bigger context window?

o3 does, with 200K tokens against 128K.

How many benchmarks do GPT-5.3 Chat and o3 share?

18 benchmarks have published results for both models. GPT-5.3 Chat has 18 scored results on Noometry and o3 has 63.

Related comparisons

Go deeper