Noometry

Model comparison

GPT-5.4 nano vs Mercury 2

GPT-5.4 nano is the stronger model overall, scoring 41.9 to 39.1 on the Noometry Index.

Last verified . 16 shared benchmarks.

GPT-5.4 nano OpenAI

41.9

Rank #125 Confirmed

Mercury 2 Inception

39.1

Rank #175 Confirmed

Summary

  • They share 16 benchmarks with published results for both. GPT-5.4 nano scores higher in 6 categories and Mercury 2 in 1 category; 6 gaps are clear of the uncertainty.
  • The widest gap is in coding, where GPT-5.4 nano leads 43.6 to 33.5.
  • The biggest single-benchmark swing is Vectara Hallucination Rate: 3.1% for GPT-5.4 nano and 12.3% for Mercury 2.
  • Mercury 2 is cheaper at $0.25 / $0.75 per million input/output tokens, against $0.20 / $1.25 for GPT-5.4 nano.
  • GPT-5.4 nano accepts more context: 400K tokens versus 128K.

Side by side

GPT-5.4 nanoMercury 2
ProviderOpenAIInception
Noometry Index41.939.1
Released2026-03-172026-02-20
WeightsProprietaryProprietary
Context window400K128K
Max output128K50K
Input $ / M tokens$0.20$0.25
Output $ / M tokens$1.25$0.75
Results tracked4017

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Category by category

Coding GPT-5.4 nano leads

GPT-5.4 nano: 43.6 (#84), Mercury 2: 33.5 (#255)

BenchmarkGPT-5.4 nanoMercury 2
SciCode46.9%38.7%
WeirdML49.2%43.2%
LMArena Coding14051391
ALE-Bench1,005785.58
LMArena WebDev—1171

Reasoning Too close to call

GPT-5.4 nano: 23.7 (#173), Mercury 2: 23.8 (#170)

BenchmarkGPT-5.4 nanoMercury 2
CritPt9.3%0.8%
LMArena Hard Prompts13811362
ARC-AGI-25.7%—
Kagi LLM Benchmark39.7%—
ARC-AGI-151.5%—
Chess Puzzles30%—
Mystery Game Puzzles9%—
DTBench80.3%—
LMCA36.9%—
Epoch Capabilities Index145.81—
ForecastBench57.3—

Math Not comparable

GPT-5.4 nano: 40.9 (#88), Mercury 2: —

BenchmarkGPT-5.4 nanoMercury 2
FrontierMath (Tiers 1-3)44.9%—
FrontierMath Tier 412.2%—
OTIS Mock AIME 2024-202587.8%—
ProofBench5%—
LMArena Math1406—
FrontierMath (Feb 2025 set)25.9%—
FrontierMath Tier 4 (v1)6.3%—

Knowledge GPT-5.4 nano leads

GPT-5.4 nano: 41.9 (#103), Mercury 2: 36.2 (#172)

BenchmarkGPT-5.4 nanoMercury 2
Vectara Hallucination Rate3.1%12.3%
LMArena Expert13961358
GPQA Diamond78.5%—
SimpleQA Verified11.7%—

Multimodal Not comparable

GPT-5.4 nano: 36.7 (#78), Mercury 2: —

BenchmarkGPT-5.4 nanoMercury 2
LMArena Vision1196—

Multilingual GPT-5.4 nano leads

GPT-5.4 nano: 48.6 (#140), Mercury 2: 46.6 (#157)

BenchmarkGPT-5.4 nanoMercury 2
LMArena Non-English13591331
LMArena Chinese13921417
LMArena Russian13631304
LMArena French1396—
LMArena German1367—
LMArena Japanese1343—
LMArena Korean1320—
LMArena Spanish1371—

Instruction Following GPT-5.4 nano leads

GPT-5.4 nano: 71.9 (#144), Mercury 2: 70.2 (#165)

BenchmarkGPT-5.4 nanoMercury 2
LMArena Instruction Following13621329

Long Context GPT-5.4 nano leads

GPT-5.4 nano: 41.6 (#137), Mercury 2: 40.5 (#154)

BenchmarkGPT-5.4 nanoMercury 2
LMArena Longer Query13661330

Writing & Preference GPT-5.4 nano leads

GPT-5.4 nano: 55.7 (#142), Mercury 2: 53.8 (#155)

BenchmarkGPT-5.4 nanoMercury 2
LMArena Text13721355
LMArena Creative Writing13141289
LMArena Multi-Turn13821358

Frequently asked questions

Is GPT-5.4 nano better than Mercury 2?

GPT-5.4 nano is the stronger model overall, scoring 41.9 to 39.1 on the Noometry Index.

Which is cheaper, GPT-5.4 nano or Mercury 2?

Mercury 2 is cheaper. It lists at $0.25 per million input tokens and $0.75 per million output tokens; GPT-5.4 nano lists at $0.20 and $1.25.

Is GPT-5.4 nano or Mercury 2 better for coding?

GPT-5.4 nano scores higher on coding benchmarks: 43.6 versus 33.5 in the Noometry coding category.

Which has the bigger context window?

GPT-5.4 nano does, with 400K tokens against 128K.

How many benchmarks do GPT-5.4 nano and Mercury 2 share?

16 benchmarks have published results for both models. GPT-5.4 nano has 40 scored results on Noometry and Mercury 2 has 17.

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