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GPT-5.4 Nano vs Step 3.5 Flash

GPT-5.4 Nano leads Step 3.5 Flash on the Artificial Analysis Intelligence Index, 20.7 to 17.0, and Step 3.5 Flash costs 4.2x less per output token ($0.30 vs $1.25 per million). Updated October 21, 2026; 35 benchmarks have a result for both.

Replace GPT-5.4 Nano Replace Step 3.5 Flash
GPT-5.4 NanoOpenAI
Coding
44.8
Overall
45.7
Output $/M
$1.25
5
Step 3.5 FlashStepFun
Coding
No data
Overall
No data
Output $/M
$0.30
30
vs boards won of 35 shared

GPT-5.4 Nano or Step 3.5 Flash: which to pick

Only GPT-5.4 Nano has a coding score, 44.8 on the Vibe Coding Index; Step 3.5 Flash has none, so the two cannot be ranked on coding.

Pick Step 3.5 Flash for output tokens 4.2x cheaper ($0.30 vs $1.25 per million) and work measured by LMArena Text: coding or LMArena Text: software and IT, where it leads.

Model AGPT-5.4 NanoOpenAI44.8/1002 independent benchmarks$0.14 per solved taskModel BStep 3.5 FlashStepFunNot benchmarkedNo coding benchmarkNo cost per solved task
Shared results
35
GPT-5.4 Nano only
50
Step 3.5 Flash only
0
Like-for-like categories
7 of 9

Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.

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-5.4 Nano 44.8 from 2 benchmarks, Step 3.5 Flash not benchmarked.
Widest category
Agentic work, 18.4 points apart on average over 1 shared benchmark.
Widest single gap
τ²-Bench Telecom: GPT-5.4 Nano 76.0% against Step 3.5 Flash 94.4%, 18.4 points apart on a 0 to 100 scale.
Output price
GPT-5.4 Nano $1.25 against Step 3.5 Flash $0.30 per million output tokens, 4.2x apart.
Context window
GPT-5.4 Nano takes 400K tokens, Step 3.5 Flash 262K.

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-5.4 NanoBarsStep 3.5 FlashTies
Coding12
Intelligence10
Agentic work01
Reasoning14
Math02
Knowledge04
General217
All shared boards530
CodingLike-for-likeSix of these boards feed the Vibe Coding Index12
Coding benchmarks for GPT-5.4 Nano and Step 3.5 Flash
BenchmarkGPT-5.4 NanoStep 3.5 FlashLeader
AA Coding Index56.1Not measuredOnly GPT-5.4 Nano measured
LiveCodeBench (Vals AI)84.0%Not measuredOnly GPT-5.4 Nano measured
SWE-bench Verified (Vals AI)69.8%Not measuredOnly GPT-5.4 Nano measured
Vibe Code Bench (Vals AI)26.1%Not measuredOnly GPT-5.4 Nano measured
Code migration (Vals AI)14.5%Not measuredOnly GPT-5.4 Nano measured
Terminal-Bench 2.1 (Vals AI)41.6%Not measuredOnly GPT-5.4 Nano measured
SciCode47.2%Not measuredOnly GPT-5.4 Nano measured
Terminal-Bench Hard (Artificial Analysis run)42.4%32.6%GPT-5.4 Nano
WeirdML49.2%Not measuredOnly GPT-5.4 Nano measured
ALE-Bench1004.5Not measuredOnly GPT-5.4 Nano measured
LMArena Text: coding14041436Step 3.5 Flash
LMArena Text: software and IT14021434Step 3.5 Flash
Neither model has a result on the other 27 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
Intelligence benchmarks for GPT-5.4 Nano and Step 3.5 Flash
BenchmarkGPT-5.4 NanoStep 3.5 FlashLeader
AA Intelligence Index20.717.0GPT-5.4 Nano
Epoch Capabilities Index146.0Not measuredOnly GPT-5.4 Nano measured
Agentic workLike-for-likePublic boards, shown as published, kept out of the index01
Agentic work benchmarks for GPT-5.4 Nano and Step 3.5 Flash
BenchmarkGPT-5.4 NanoStep 3.5 FlashLeader
AA Agentic Index16.0Not measuredOnly GPT-5.4 Nano measured
Finance Agent (Vals AI)38.2%Not measuredOnly GPT-5.4 Nano measured
Tax Agent Bench (Vals AI)5.0%Not measuredOnly GPT-5.4 Nano measured
Legal Research Bench (Vals AI)6.3%Not measuredOnly GPT-5.4 Nano measured
Excel Modeling Benchmark (Vals AI)44.8%Not measuredOnly GPT-5.4 Nano measured
τ²-Bench Telecom76.0%94.4%Step 3.5 Flash
Neither model has a result on the other 35 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index14
Reasoning benchmarks for GPT-5.4 Nano and Step 3.5 Flash
BenchmarkGPT-5.4 NanoStep 3.5 FlashLeader
GPQA Diamond77.5%Not measuredOnly GPT-5.4 Nano measured
MMMU Pro (Vals AI)73.6%Not measuredOnly GPT-5.4 Nano measured
GPQA Diamond (Artificial Analysis run)81.7%83.1%Step 3.5 Flash
Humanity's Last Exam (Artificial Analysis run)28.3%24.5%GPT-5.4 Nano
GPQA Diamond (Epoch AI run)78.5%Not measuredOnly GPT-5.4 Nano measured
ARC-AGI51.5%Not measuredOnly GPT-5.4 Nano measured
ARC-AGI-25.7%Not measuredOnly GPT-5.4 Nano measured
Chess puzzles45.0%Not measuredOnly GPT-5.4 Nano measured
Mystery game puzzles9.0%Not measuredOnly GPT-5.4 Nano measured
LMArena Text: hard prompts13811411Step 3.5 Flash
LMArena Text: expert13961421Step 3.5 Flash
LMArena Text: hard prompts in English13871421Step 3.5 Flash
LMArena Vision: diagrams1210Not measuredOnly GPT-5.4 Nano measured
LMArena Vision: homework1225Not measuredOnly GPT-5.4 Nano measured
Kagi LLM Benchmark39.7%Not measuredOnly GPT-5.4 Nano measured
Neither model has a result on the other 7 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index02
Math benchmarks for GPT-5.4 Nano and Step 3.5 Flash
BenchmarkGPT-5.4 NanoStep 3.5 FlashLeader
AIME88.8%Not measuredOnly GPT-5.4 Nano measured
OTIS Mock AIME87.8%Not measuredOnly GPT-5.4 Nano measured
FrontierMath, tiers 1 to 344.9%Not measuredOnly GPT-5.4 Nano measured
FrontierMath, tier 412.2%Not measuredOnly GPT-5.4 Nano measured
ProofBench5.0%Not measuredOnly GPT-5.4 Nano measured
LMArena Text: math14051408Step 3.5 Flash
LMArena Text: mathematical work14091421Step 3.5 Flash
Neither model has a result on the other 6 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index04
Knowledge benchmarks for GPT-5.4 Nano and Step 3.5 Flash
BenchmarkGPT-5.4 NanoStep 3.5 FlashLeader
MMLU Pro77.2%Not measuredOnly GPT-5.4 Nano measured
LegalBench (Vals AI)77.9%Not measuredOnly GPT-5.4 Nano measured
CaseLaw (Vals AI)51.9%Not measuredOnly GPT-5.4 Nano measured
CorpFin (Vals AI)61.2%Not measuredOnly GPT-5.4 Nano measured
TaxEval (Vals AI)67.4%Not measuredOnly GPT-5.4 Nano measured
MortgageTax (Vals AI)59.1%Not measuredOnly GPT-5.4 Nano measured
MedCode (Vals AI)41.0%Not measuredOnly GPT-5.4 Nano measured
SimpleQA Verified11.7%Not measuredOnly GPT-5.4 Nano measured
LMArena Text: science13741415Step 3.5 Flash
LMArena Text: medicine and healthcare13691408Step 3.5 Flash
LMArena Text: legal and government13681408Step 3.5 Flash
LMArena Text: business and finance13661394Step 3.5 Flash
Neither model has a result on the other 6 boards here
Web designNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Web design benchmarks for GPT-5.4 Nano and Step 3.5 Flash
BenchmarkGPT-5.4 NanoStep 3.5 FlashLeader
Neither model has a result on 9 boards here
GeneralLike-for-likePublic boards, shown as published, kept out of the index217
General benchmarks for GPT-5.4 Nano and Step 3.5 Flash
BenchmarkGPT-5.4 NanoStep 3.5 FlashLeader
SAGE (Vals AI)38.1%Not measuredOnly GPT-5.4 Nano measured
MedScribe (Vals AI)77.1%Not measuredOnly GPT-5.4 Nano measured
Vals Multimodal Index47.6%Not measuredOnly GPT-5.4 Nano measured
IFBench75.9%66.5%GPT-5.4 Nano
Long context reasoning (AA-LCR)76.7%63.0%GPT-5.4 Nano
DTBench80.3%Not measuredOnly GPT-5.4 Nano measured
LMCA36.9%Not measuredOnly GPT-5.4 Nano measured
LMArena Text13721403Step 3.5 Flash
LMArena Text: instruction following13621385Step 3.5 Flash
LMArena Text: creative writing13151357Step 3.5 Flash
LMArena Vision1196Not measuredOnly GPT-5.4 Nano measured
LMArena Text: English13811417Step 3.5 Flash
LMArena Text: non-English13591385Step 3.5 Flash
LMArena Text: Chinese13911446Step 3.5 Flash
LMArena Text: German13681405Step 3.5 Flash
LMArena Text: Japanese13431353Step 3.5 Flash
LMArena Text: Korean13211351Step 3.5 Flash
LMArena Text: French13951421Step 3.5 Flash
LMArena Text: Spanish13711419Step 3.5 Flash
LMArena Text: Russian13631385Step 3.5 Flash
LMArena Text: Polish13661389Step 3.5 Flash
LMArena Text: multi-turn13821404Step 3.5 Flash
LMArena Text: longer queries13651402Step 3.5 Flash
LMArena Text: writing and language13381372Step 3.5 Flash
LMArena Text: entertainment and media13251360Step 3.5 Flash
LMArena Vision: English1202Not measuredOnly GPT-5.4 Nano measured
LMArena Vision: Chinese1232Not measuredOnly GPT-5.4 Nano measured
LMArena Vision: reading text1204Not measuredOnly GPT-5.4 Nano measured
LMArena Vision: humor1161Not measuredOnly GPT-5.4 Nano measured
LMArena Vision: recognizing things1141Not measuredOnly GPT-5.4 Nano measured
LMArena Vision: creative writing1159Not measuredOnly GPT-5.4 Nano measured
Neither model has a result on the other 15 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for GPT-5.4 Nano and Step 3.5 Flash
BenchmarkGPT-5.4 NanoStep 3.5 FlashLeader
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-5.4 Nano$0.0008Fits in one request
Step 3.5 Flash$0.0003Fits in one request

Step 3.5 Flash costs less

Repository review

50K input + 3K output tokens

GPT-5.4 Nano$0.014Fits in one request
Step 3.5 Flash$0.0059Fits in one request

Step 3.5 Flash costs less

Agent loop

200K input + 10K output tokens

GPT-5.4 Nano$0.052Fits in one request
Step 3.5 Flash$0.023Fits in one request

Step 3.5 Flash 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-5.4 Nano and Step 3.5 Flash
SpecificationOpenAI GPT-5.4 NanoStepFun Step 3.5 Flash
MakerOpenAIStepFun
WeightsNo public weights listedOpen weights
ReleasedMarch 17, 2026January 29, 2026
Context window400K262K
Input $/Mtok$0.20$0.10
Output $/Mtok$1.25$0.30
Coding index44.8Not benchmarked
Independent measurements behind it20
Cost per solved task$0.14Not computable
SourceOpenRouter listingOpenRouter listing

Questions

Is GPT-5.4 Nano better than Step 3.5 Flash for coding?

Only GPT-5.4 Nano has a coding score, 44.8 on the Vibe Coding Index; Step 3.5 Flash has none, so the two cannot be ranked on coding. Pick Step 3.5 Flash for output tokens 4.2x cheaper ($0.30 vs $1.25 per million) and work measured by LMArena Text: coding or LMArena Text: software and IT, where it leads.

Which is cheaper, GPT-5.4 Nano or Step 3.5 Flash?

GPT-5.4 Nano costs $0.20 per million input tokens and $1.25 per million output tokens; Step 3.5 Flash costs $0.10 and $0.30. Cost per solved task is known for GPT-5.4 Nano only.

Which has the bigger context window, GPT-5.4 Nano or Step 3.5 Flash?

GPT-5.4 Nano, with 400K tokens against 262K.

How many benchmarks is the GPT-5.4 Nano vs Step 3.5 Flash comparison based on?

35 benchmarks have a result for both models as of October 21, 2026. GPT-5.4 Nano's coding index rests on 2 independent benchmarks and Step 3.5 Flash's on 0. Where only one model has a result, the page says so instead of naming a winner.

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