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ModelCap

Step 5 Preview

Arena #83NewNo linked weights

StepFun·#39 of 344 on the current board·cheaper than #38 GPT-5.4 Mini

Step 5 Preview is a language model from StepFun. It ranks #39 of 344 on ModelCap's current board, with an Index score of 69.4, measured on 3 public benchmarks. Its score range of 63.8–75.0 spans positions #28–#60. It is listed at $1.00 per million input tokens and $2.70 per million output tokens from one provider. It reads up to 1M tokens of context, with no downloadable weights linked in the current source data.

Figures as of 11 Oct 2026, 15:20 UTC · download the public dataset · methodology

ModelCap Index · Current board
69.4#39
Measured on 3 public benchmarks · range 63.8–75.0
Evidence as of 8 Oct 2026, 00:00 UTC
Market Gravity
61.1Increased by 4.4
Secondary market signal
Input
$1.00
per 1M tokens
Output
$2.70
per 1M tokens
Context
1M
tokens
Providers
1
endpoint

Providers

Uptime measured over the last 30 minutes
ProviderInputOutputContextQuantUptime
StepFunfp8$1.00$2.701Mfp8100.0%

Reasoning efforts

Best supported result can inform ModelCap

Published Max, X-High, High and other configurations for this model. These are sourced scores, not head-to-head essays.

EffortAgent scoreSource rankSampleSource
Default
Step 5 Preview
0.01%
CI -1.6–1.6%
#331.4M obs
11K sessions
LMArena Agent
Match 100%

ModelCap Index · Current board

Methodology
69.4
Measured on 3 public benchmarks
Current board
#39 of 344
Score range
63.8–75.0
Rank range
#28–#60
Evidence as of
8 Oct 2026, 00:00 UTC
Benchmarks used
Arena Coding, Arena Overall, LMArena Agent
Technical details
Public rank basis
Measured (measured)
Evidence label
Measured · 3 public benchmark observations across 3 boards
Index support
54.7% · moderate
Identity binding
Exact catalogue product · stepfun/stepfun/step-5-preview · aggregates disclosed benchmark configurations · endpoint configuration not claimed
Index observations used
3
Qualified Index evidence point
69.4
Bayesian Evidence Score · measured evidence input only

BES normalizes admitted public benchmark evidence for measured Index rows. Its legacy score and observables prior do not define the public language rank.

Observed capability
69.4
Evidence status
confirmed · 85% mass
General preference
70.5
Coding
71.9
Agents & tools
45.2
Reasoning
—
Evidence breadth
97%
Evidence coverage
55%
Market and catalogue signals · secondary, never the language Index rank
Usage (OpenRouter popularity)
72.3
Liquidity (providers × uptime)
35.5
Open reach (HF downloads)
—
Surface (context / tools / modalities)
100.0
Freshness
98.8
  • · OpenRouter popularity #5
  • · 1 live provider
  • · Catalogue: context 1000000, reasoning, tools, modalities Text/Image/Video
  • · First seen 2026-10-08

These adoption and deployment observations remain context only. They do not change this model's ModelCap Index score or rank.

BES evidence selected · measured input only

The bounded 0–100 capability score blends each source’s competitive placement with its published achievement, then combines capability families. Evidence breadth adds a modest uncertainty adjustment; price and popularity are not part of benchmark-led rank.

Deployment readiness

Metadata index
44.8
limited · 56% metadata coverage
Not capability
Artifact reproducibility
0.0
Access & legal clarity
30.3
Deployability
80.0
Evaluation provenance
73.7

Not yet published: a pinned repository revision, the architecture and model type, a parameter count, safetensors weight metadata, the base model it derives from, a declared licence, a link to the licence terms, pinned evaluation dataset versions.

A metadata completeness and deployability index—not a safety certification, quality grade, or production-readiness claim.

Market activity

Venue coverage
Market Gravity
61.1
OpenRouter weekly popularity
#5 of 332

Market Gravity uses OpenRouter’s full-catalogue popularity order. Sparse Vercel top-ten observations appear only when published and do not affect the score.

Arena preference

Status
Ranked
Source
LMArena
Official rank
#83 of 414
Rating
1447.3
95% confidence interval
1439–1456
Votes
5K
Source published at
8 Oct 2026, 00:00 UTC
Category
overall
Identity match confidence
100%

Market Gravity breakdown

Usage55%
72.3

OpenRouter weekly popularity across the full model catalogue.

Liquidity25%
35.5

Independent providers versus the model's open or closed cohort, weighted by uptime.

Open reach15%
50.0

Hugging Face 30-day downloads for open models; neutral for closed models.

Freshness5%
98.8

Time since first public availability, on a six-month half-life.

Specification

Model ID
stepfun/step-5-preview
Context window
1M tokens
Declared output cap
64K tokens

OpenRouter catalogue or provider-endpoint declaration. Limits can vary by provider and prompt length; a model-wide maximum has not been independently verified. OpenRouter metadata

Inputs
Text, Image, Video
Outputs
Text
Tokenizer
Other
Cached input tokens
$0.05 / 1M
First seen on OpenRouter
8 Oct 2026

Capabilities

  • Supported: Reasoning
  • Supported: Tool use
  • Supported: Structured output
  • Supported: Response format
  • Not supported: Moderated

Benchmark leaderboards featuring Step 5 Preview

All leaderboards
Public benchmark boards on which Step 5 Preview has a published result
LeaderboardScoreSource rankConfigurationPublished
Arena text leaderboardArena (LMArena)14471439–1456#83 of 414Not reported8 Oct 2026
Arena coding leaderboardArena (LMArena)15031486–1519#71 of 409Default8 Oct 2026
LMArena Agent leaderboardLMArena0.0%-1.6%–1.6%#33 of 52Default8 Oct 2026
Artificial Analysis Intelligence IndexArtificial Analysis43.7#41 of 205Reasoning8 Oct 2026
Humanity's Last Exam (Artificial Analysis run)Artificial Analysis46.5%#40 of 655Reasoning8 Oct 2026

Alternatives to Step 5 Preview, by the numbers

Ranked neighbours

Models within 3 places of #39 on the ModelCap Index.

Cheaper at a similar or higher Index

Index score within 3 points of, or above, this model's, with a lower listed blended price (3:1 input:output).

Other ranked StepFun models

The same publisher's other current models with a public Index position.

Step 5 Preview: common questions

How does Step 5 Preview rank among AI models?

Step 5 Preview holds ModelCap Index position #39 of 344 ranked language models as of 11 October 2026, with an Index score of 69.4 (interval 63.8–75.0); evidence: measured. The Index combines public benchmark boards with published uncertainty; the methodology page explains the weighting.

How much does Step 5 Preview cost per 1M tokens?

Step 5 Preview is listed at $1.00 per 1M input tokens and $2.70 per 1M output tokens as of 11 October 2026. Prices come from the OpenRouter catalogue and re-observe on every refresh. For 1,000 requests using 2,000 input and 500 output tokens each, the listed rates imply $3.35 total (2M input + 0.5M output). This excludes caching, batch discounts, prompt-length tiers, tool charges and retries; verify the chosen endpoint's rate and limits before budgeting.

What is the context window of Step 5 Preview?

Step 5 Preview has a published context window of 1M tokens (1,000,000). The snapshot lists a 64,000 token catalogue-declared route output cap. OpenRouter catalogue or provider-endpoint declaration. Limits can vary by provider and prompt length; a model-wide maximum has not been independently verified. The providers table lists each endpoint's context limit.

Is Step 5 Preview open-weight?

No linked weights. No downloadable model weights are linked in the current source data. This does not identify every API or chat product that offers the model.

Which API providers serve Step 5 Preview?

One provider serves Step 5 Preview through OpenRouter as of 11 October 2026: StepFun. Each provider's price, context limit, quantization and measured uptime are in the providers table above.

Which benchmarks has Step 5 Preview been evaluated on?

Step 5 Preview has published results on 5 public boards tracked by ModelCap as of 11 October 2026: Arena text 1447 (#83 of 414), Arena coding 1503 (#71 of 409), LMArena Agent 0.0% (#33 of 52), AA Intelligence Index 43.7 (#41 of 205) and AA Humanity's Last Exam 46.5% (#40 of 655). Each board page ranks every tracked model on that benchmark. The ModelCap Index scores the results its methodology admits, with published uncertainty, and shows reference boards without scoring them.

When was Step 5 Preview released?

Step 5 Preview first appeared in the catalogue on 8 Oct 2026. It is the current version in its family. Rank and price movements since then are recorded on the site's changes feed.