GPT-5.4 Mini vs Step 5 Preview
Step 5 Preview leads GPT-5.4 Mini on coding, 61.1 to 35.8 on the Vibe Coding Index, and Step 5 Preview costs 1.7x less per output token ($2.70 vs $4.50 per million). Updated October 21, 2026; 45 benchmarks have a result for both.
GPT-5.4 Mini or Step 5 Preview: which to pick
Pick Step 5 Preview for coding: it scores 61.1 on the Vibe Coding Index against 35.8 for GPT-5.4 Mini, though on 4 benchmarks against 5.
Pick GPT-5.4 Mini for work measured by LMArena Vision: homework or LMArena Text: French, where it leads.
- Shared results
- 45
- GPT-5.4 Mini only
- 44
- Step 5 Preview only
- 16
- 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.
Coding
Vibe Coding Index, six public coding benchmarks
Step 5 Preview
Step 5 Preview scores 61.1 against 35.8.
5 and 4 benchmarks behind the scores
Intelligence
AA Intelligence Index
Step 5 Preview
Step 5 Preview leads, 43.7 against 24.1.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only GPT-5.4 Mini has a AA Agentic Index result, 17.9.
Directional only
Reasoning
GPQA Diamond
No call
Only GPT-5.4 Mini has a GPQA Diamond result, 83.1%.
Directional only
Math
AIME
No call
Only GPT-5.4 Mini has a AIME result, 95.6%.
Directional only
Knowledge
MMLU Pro
No call
Only GPT-5.4 Mini has a MMLU Pro result, 84.5%.
Directional only
Long documents
Listed context window
Step 5 Preview
Step 5 Preview takes 1.05M tokens against 400K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Step 5 Preview
GPT-5.4 Mini $0.0030, Step 5 Preview $0.0024 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only GPT-5.4 Mini has the number, $0.70.
Directional only
At a glance
- Coding index
- GPT-5.4 Mini 35.8 from 5 benchmarks, Step 5 Preview 61.1 from 4 benchmarks.
- Widest category
- Coding, 20.9 points apart on average over 9 shared benchmarks.
- Widest single gap
- Terminal-Bench 4 (Vals AI): GPT-5.4 Mini 2.5% against Step 5 Preview 31.8%, 39.1 points apart on a 0 to 100 scale.
- Output price
- GPT-5.4 Mini $4.50 against Step 5 Preview $2.70 per million output tokens, 1.7x apart.
- Context window
- GPT-5.4 Mini takes 400K tokens, Step 5 Preview 1.05M.
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.
| Category | GPT-5.4 Mini | Bars | Step 5 Preview | Ties |
|---|---|---|---|---|
| Coding | 0 | 9 | ||
| Intelligence | 0 | 1 | ||
| Agentic work | 0 | 4 | ||
| Reasoning | 1 | 5 | ||
| Math | 0 | 3 | ||
| Knowledge | 0 | 4 | ||
| General | 1 | 17 | ||
| All shared boards | 2 | 43 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index09
| Benchmark | GPT-5.4 Mini | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench coding | Not measured | 85.6% | Only Step 5 Preview measured |
| LMArena WebDev | 1397 | 1567 | Step 5 Preview |
| AA Coding Index | 56.1 | Not measured | Only GPT-5.4 Mini measured |
| LiveCodeBench (Vals AI) | 81.5% | Not measured | Only GPT-5.4 Mini measured |
| SWE-bench Verified (Vals AI) | 73.0% | Not measured | Only GPT-5.4 Mini measured |
| Terminal-Bench 4 (Vals AI) | 2.5% | 31.8% | Step 5 Preview |
| Vibe Code Bench (Vals AI) | 48.0% | 70.4% | Step 5 Preview |
| Code migration (Vals AI) | 12.9% | 39.0% | Step 5 Preview |
| ProgramBench (Vals AI) | 0.0% | Not measured | Only GPT-5.4 Mini measured |
| IOI (Vals AI) | Not measured | 38.1% | Only Step 5 Preview measured |
| Terminal-Bench 2.1 (Vals AI) | 54.7% | Not measured | Only GPT-5.4 Mini measured |
| SWE-bench Multimodal (Vals AI) | Not measured | 40.8% | Only Step 5 Preview measured |
| SciCode | 52.1% | 58.9% | Step 5 Preview |
| Terminal-Bench Hard (Artificial Analysis run) | 52.3% | Not measured | Only GPT-5.4 Mini measured |
| FrontierCode | 27.0% | Not measured | Only GPT-5.4 Mini measured |
| WeirdML | 60.3% | Not measured | Only GPT-5.4 Mini measured |
| ALE-Bench | 1188.6 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: coding | 1438 | 1485 | Step 5 Preview |
| LMArena Text: software and IT | 1436 | 1473 | Step 5 Preview |
| LMArena WebDev: React | 1386 | 1583 | Step 5 Preview |
| LMArena WebDev: HTML | 1419 | 1556 | Step 5 Preview |
| LMArena WebDev: from an image | Not measured | 1550 | Only Step 5 Preview measured |
| Neither model has a result on the other 17 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | GPT-5.4 Mini | Step 5 Preview | Leader |
|---|---|---|---|
| AA Intelligence Index | 24.1 | 43.7 | Step 5 Preview |
| Epoch Capabilities Index | 148.7 | Not measured | Only GPT-5.4 Mini measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index04
| Benchmark | GPT-5.4 Mini | Step 5 Preview | Leader |
|---|---|---|---|
| AA Agentic Index | 17.9 | Not measured | Only GPT-5.4 Mini measured |
| LiveBench research | Not measured | 72.8% | Only Step 5 Preview measured |
| LiveBench browser | Not measured | 24.0% | Only Step 5 Preview measured |
| LiveBench long agentic | Not measured | 27.5% | Only Step 5 Preview measured |
| SREBench (Vals AI) | Not measured | 0.4% | Only Step 5 Preview measured |
| Finance Agent (Vals AI) | 45.4% | 50.7% | Step 5 Preview |
| Tax Agent Bench (Vals AI) | 8.8% | 27.3% | Step 5 Preview |
| Legal Research Bench (Vals AI) | 12.5% | 40.4% | Step 5 Preview |
| Excel Modeling Benchmark (Vals AI) | 45.4% | 57.1% | Step 5 Preview |
| BioMysteryBench (Vals AI) | Not measured | 67.4% | Only Step 5 Preview measured |
| Terminal-Bench-Science (Vals AI) | Not measured | 2.9% | Only Step 5 Preview measured |
| Vals Science Index | Not measured | 29.6% | Only Step 5 Preview measured |
| τ²-Bench Telecom | 83.3% | Not measured | Only GPT-5.4 Mini measured |
| DeepResearch Bench | 36.3% | Not measured | Only GPT-5.4 Mini measured |
| Neither model has a result on the other 27 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index15
| Benchmark | GPT-5.4 Mini | Step 5 Preview | Leader |
|---|---|---|---|
| GPQA Diamond | 83.1% | Not measured | Only GPT-5.4 Mini measured |
| LiveBench reasoning | Not measured | 83.8% | Only Step 5 Preview measured |
| MysteryMechanism (Vals AI) | Not measured | 18.5% | Only Step 5 Preview measured |
| MMMU Pro (Vals AI) | 79.3% | Not measured | Only GPT-5.4 Mini measured |
| GPQA Diamond (Artificial Analysis run) | 87.5% | Not measured | Only GPT-5.4 Mini measured |
| Humanity's Last Exam (Artificial Analysis run) | 28.1% | 46.5% | Step 5 Preview |
| GPQA Diamond (Epoch AI run) | 86.9% | Not measured | Only GPT-5.4 Mini measured |
| ARC-AGI | 63.7% | Not measured | Only GPT-5.4 Mini measured |
| ARC-AGI-2 | 18.9% | Not measured | Only GPT-5.4 Mini measured |
| Chess puzzles | 23.0% | Not measured | Only GPT-5.4 Mini measured |
| Mystery game puzzles | 11.0% | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: hard prompts | 1424 | 1461 | Step 5 Preview |
| LMArena Text: expert | 1435 | 1485 | Step 5 Preview |
| LMArena Text: hard prompts in English | 1420 | 1454 | Step 5 Preview |
| LMArena Vision: diagrams | 1266 | 1308 | Step 5 Preview |
| LMArena Vision: homework | 1285 | 1265 | GPT-5.4 Mini |
| Kagi LLM Benchmark | 37.9% | Not measured | Only GPT-5.4 Mini measured |
| Neither model has a result on the other 5 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index03
| Benchmark | GPT-5.4 Mini | Step 5 Preview | Leader |
|---|---|---|---|
| AIME | 95.6% | Not measured | Only GPT-5.4 Mini measured |
| OTIS Mock AIME | 88.9% | Not measured | Only GPT-5.4 Mini measured |
| FrontierMath, tiers 1 to 3 | 51.2% | Not measured | Only GPT-5.4 Mini measured |
| FrontierMath, tier 4 | 9.8% | Not measured | Only GPT-5.4 Mini measured |
| ProofBench | 21.0% | 42.0% | Step 5 Preview |
| LMArena Text: math | 1418 | 1458 | Step 5 Preview |
| LMArena Text: mathematical work | 1429 | 1460 | Step 5 Preview |
| Neither model has a result on the other 6 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index04
| Benchmark | GPT-5.4 Mini | Step 5 Preview | Leader |
|---|---|---|---|
| MMLU Pro | 84.5% | Not measured | Only GPT-5.4 Mini measured |
| CaseLaw (Vals AI) | 51.7% | Not measured | Only GPT-5.4 Mini measured |
| CorpFin (Vals AI) | 60.9% | Not measured | Only GPT-5.4 Mini measured |
| TaxEval (Vals AI) | 71.2% | Not measured | Only GPT-5.4 Mini measured |
| MortgageTax (Vals AI) | 63.5% | Not measured | Only GPT-5.4 Mini measured |
| SimpleQA Verified | 29.4% | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: science | 1417 | 1454 | Step 5 Preview |
| LMArena Text: medicine and healthcare | 1395 | 1439 | Step 5 Preview |
| LMArena Text: legal and government | 1414 | 1437 | Step 5 Preview |
| LMArena Text: business and finance | 1418 | 1435 | Step 5 Preview |
| Neither model has a result on the other 8 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index1 board, none shared
| Benchmark | GPT-5.4 Mini | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench design | Not measured | 76.9% | Only Step 5 Preview measured |
| Neither model has a result on the other 8 boards here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index117
| Benchmark | GPT-5.4 Mini | Step 5 Preview | Leader |
|---|---|---|---|
| LiveBench data analysis | Not measured | 63.5% | Only Step 5 Preview measured |
| Public Benefits Bench (Vals AI) | Not measured | 58.1% | Only Step 5 Preview measured |
| SAGE (Vals AI) | 50.8% | Not measured | Only GPT-5.4 Mini measured |
| Vals Multimodal Index | 54.2% | Not measured | Only GPT-5.4 Mini measured |
| IFBench | 73.3% | Not measured | Only GPT-5.4 Mini measured |
| Long context reasoning (AA-LCR) | 77.0% | 88.3% | Step 5 Preview |
| DTBench | 80.0% | Not measured | Only GPT-5.4 Mini measured |
| LMCA | 40.8% | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text | 1412 | 1440 | Step 5 Preview |
| LMArena Text: instruction following | 1405 | 1438 | Step 5 Preview |
| LMArena Text: creative writing | 1370 | 1409 | Step 5 Preview |
| LMArena Vision | 1245 | 1265 | Step 5 Preview |
| LMArena Text: English | 1412 | 1447 | Step 5 Preview |
| LMArena Text: non-English | 1405 | 1428 | Step 5 Preview |
| LMArena Text: Chinese | 1446 | 1500 | Step 5 Preview |
| LMArena Text: German | 1408 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: Japanese | 1375 | 1383 | Step 5 Preview |
| LMArena Text: Korean | 1370 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: French | 1441 | 1438 | GPT-5.4 Mini |
| LMArena Text: Spanish | 1405 | 1441 | Step 5 Preview |
| LMArena Text: Russian | 1417 | 1433 | Step 5 Preview |
| LMArena Text: Polish | 1415 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Text: multi-turn | 1429 | 1437 | Step 5 Preview |
| LMArena Text: longer queries | 1408 | 1449 | Step 5 Preview |
| LMArena Text: writing and language | 1393 | 1425 | Step 5 Preview |
| LMArena Text: entertainment and media | 1373 | 1412 | Step 5 Preview |
| LMArena Vision: English | 1244 | 1290 | Step 5 Preview |
| LMArena Vision: Chinese | 1286 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Vision: reading text | 1253 | 1282 | Step 5 Preview |
| LMArena Vision: humor | 1235 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Vision: recognizing things | 1218 | Not measured | Only GPT-5.4 Mini measured |
| LMArena Vision: creative writing | 1222 | Not measured | Only GPT-5.4 Mini measured |
| Neither model has a result on the other 14 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | GPT-5.4 Mini | Step 5 Preview | Leader |
|---|---|---|---|
| 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
Step 5 Preview costs less
Repository review
50K input + 3K output tokens
GPT-5.4 Mini costs less
Agent loop
200K input + 10K output tokens
GPT-5.4 Mini 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.
| Specification | OpenAI GPT-5.4 Mini | StepFun Step 5 Preview |
|---|---|---|
| Maker | OpenAI | StepFun |
| Weights | No public weights listed | Open weights |
| Released | March 17, 2026 | October 8, 2026 |
| Context window | 400K | 1.05M |
| Input $/Mtok | $0.75 | $1.00 |
| Output $/Mtok | $4.50 | $2.70 |
| Coding index | 35.8 | 61.1 |
| Independent measurements behind it | 5 | 4 |
| Cost per solved task | $0.70 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is GPT-5.4 Mini better than Step 5 Preview for coding?
Pick Step 5 Preview for coding: it scores 61.1 on the Vibe Coding Index against 35.8 for GPT-5.4 Mini, though on 4 benchmarks against 5. Pick GPT-5.4 Mini for work measured by LMArena Vision: homework or LMArena Text: French, where it leads.
Which is cheaper, GPT-5.4 Mini or Step 5 Preview?
GPT-5.4 Mini costs $0.75 per million input tokens and $4.50 per million output tokens; Step 5 Preview costs $1.00 and $2.70. Cost per solved task is known for GPT-5.4 Mini only.
Which has the bigger context window, GPT-5.4 Mini or Step 5 Preview?
Step 5 Preview, with 1.05M tokens against 400K.
How many benchmarks is the GPT-5.4 Mini vs Step 5 Preview comparison based on?
45 benchmarks have a result for both models as of October 21, 2026. GPT-5.4 Mini's coding index rests on 5 independent benchmarks and Step 5 Preview's on 4. Where only one model has a result, the page says so instead of naming a winner.