STEALTHMARK · HEAD TO HEAD

All comparisons ↗

Claude Haiku 5.5 vs Step 5 Preview

Claude Haiku 5.5 leads Step 5 Preview by 10.5 points on StealthMark, 49.5 to 39.0. It leads on 8 of 9 benchmarks, including both games, and Step 5 Preview on 1. Claude Haiku 5.5 scores higher on Beach, with its largest category advantage in anatomy & construction.

See the difference ↘
All results ↗
All results ↗

Overall StealthMark

49.5/100Overall rank 17/53
39.0/100Overall rank 36/53

General Intelligence

47.6/100
37.1/100

Visual Intelligence

52.8/100
41.9/100

Reasoning efficiency

On every task, result quality and reasoning tokens are each compared with all measured models and weighed equally. Each dot is one model.

Single-step reasoning Result quality weighed against reasoning tokens on a single problem

Multi-step reasoning Result quality weighed against reasoning tokens across connected steps, as in agentic workflows

  • Claude Haiku 5.5

BENCHMARK BY BENCHMARK

Where each model leads

  • Claude Haiku 5.5
  • Step 5 Preview
  • Other models
  • Median

DATASHEET

Specs and pricing

Both take about 1M tokens of context.

  • Claude Haiku 5.5
  • Step 5 Preview
  • Other models
  • Median
PricePer 1M output tokens, input below
Claude Haiku 5.5: $0.50$0.10 inputStep 5 Preview: No list price
Context windowTokens per request, max output below
Claude Haiku 5.5: 1MTied128K max outputStep 5 Preview: 1MTied
Output speedTokens per second, our measurement
Claude Haiku 5.5: 402tokens/sStep 5 Preview: Not measured
SizeTotal and active parameters
Claude Haiku 5.5: Not disclosedStep 5 Preview: 600B27B active
Developer
AnthropicStepFun
Released
7 Oct 2026Not published
Origin
United StatesNot published
Input → output
Text, image → textText, image, video → text
Architecture
Not publishedSparse mixture-of-experts; 92 layers (88 MoE), 352 routed experts with 8 selected per token plus a shared expert; grouped-query attention with 512-token sliding windows and full attention every fourth layer; 3 multi-token-prediction layers; vision tower for image and video input

Full datasheets, every price and sourceClaude Haiku 5.5 ↗Step 5 Preview ↗

Anticipating threats and planning ahead. Collect coins while avoiding ghosts. Ghosts move before the player each turn, and collisions cost a life. 3 levels in sequence, up to 66 turns in total. Earlier moves and outcomes carry forward, testing learning across levels.

Claude Haiku 5.5 34.4/100Rank 26/49

Survived 1 of 3
Foresight: complete playing field
Level 39 ptsTurn 20 / 20

Step 5 Preview 59.9/100Rank 42/491 of 3 levels

1 of 3 played
Foresight: complete playing field
Level 122 ptsTurn 28 / 28

Points per level

LevelClaude Haiku 5.5Step 5 Preview
Level 1Second Thoughts
4 ptsOut of lives
22 ptsSurvived
Level 2Pressure Pot
7 ptsOut of lives
Pending
Level 3Hide or Flight
9 ptsSurvived
Pending

Cooperative planning and learning from experience. Coordinate two robots to push numbered cores onto matching sockets. Pressure plates hold doors open; moving either robot uses one turn. 5 levels in sequence, up to 152 turns in total. Earlier moves and outcomes carry forward, testing learning across levels.

Claude Haiku 5.5 78.3/100Rank 11/50

Cleared 5 of 5
Latch: complete playing field
Level 520.6 ptsTurn 27 / 40

Step 5 Preview 40.7/100Rank 28/50

Cleared 4 of 5
Latch: complete playing field
Level 515 ptsTurn 35 / 40

Points per level

LevelClaude Haiku 5.5Step 5 Preview
Level 1Hold the door
5 ptsCleared
5.2 ptsCleared
Level 2Crossfeed
9.8 ptsCleared
9 ptsCleared
Level 3Relay vault
18.8 ptsCleared
18.6 ptsCleared
Level 4Passing bay
18.2 ptsClearedFinished early · 3 beacons left
15.6 ptsClearedFinished early · 3 beacons left
Level 5Second thoughts
20.6 ptsCleared
15 ptsFinished early

Newton's Mirror

Same task instructions

Physics, perspective and recursive reflections, tested together. Explore the test ↗

The judgment

Claude Haiku 5.5

The centered sphere, compact airborne black blob and differentiated cyan/crimson interaction support substantial state and placement credit. The few recognizable sphere and panel images establish limited optical relationships, but most of the required mirror system is missing. Rounded volume and localized paint warrant substantial material credit despite the soft, illustrative finish.

Step 5 Preview

The main sphere, airborne black and small colored features occupy broadly appropriate positions. Most of the defining mirror system is absent, and paint interaction remains only partially supported. The small paint features do not visibly establish a separate volume-scale violation.

Score breakdown

CategoryClaude Haiku 5.5Step 5 Preview
State at 600 ms25.0/2520.0/25
Camera and placement8.0/1513.5/15
Reflections24.5/12020.0/120
Materials and scale7.5/107.0/10
Floor-damage reward0.0/100.0/10

Benchmark task

A spinning metal sphere and paint in a mirrored room test physical reasoning, perspective and consistency across repeated reflections.

Selfie

Different task instructions

Visual construction and creative interpretation.

The judgment

Claude Haiku 5.5

A coherent coral squid emblem with a compact mantle, restrained face and clean centered presentation. Its radial silhouette and floating placement work, but sharp arm tips, crowded roots and sparse surface modeling limit softness, construction and finish.

Step 5 Preview

A charming diagonal climber and warm palette communicate the central idea. Simple rounded construction, crowded limb counting, uncertain footholds and an unattached upper shelf limit its physical coherence. Growth bands and the yarn trail add specificity, but the requested material distinctions and unravelled bootie remain underdeveloped.

Score breakdown

CategoryClaude Haiku 5.5Step 5 Preview
Task & likeness6.5/106.0/10
Anatomy & construction4.0/104.5/10
Space & placement6.5/105.0/10
Light & reflections4.0/105.5/10
Purposeful detail3.5/105.5/10
Artistry & character3.5/105.0/10
Materials & effects4.5/106.0/10
Visual integrity7.0/105.0/10

Benchmark task

Claude Haiku 5.5

A coral squid with spreading arms tests connected anatomy, balanced composition and soft surface shading.

Step 5 Preview

Character scenes test expression, anatomy, materials and coherent visual construction.

Mona Lisa

Different task instructions

Precise visual recall and portrait reconstruction.

The judgment

Claude Haiku 5.5

A recognizable but basic Mona Lisa reinterpretation. Clean contours and smooth facial lighting provide coherence and volume. Replication remains limited by the frontal pose, elongated neck, schematic expression, unresolved crossed hands and sparse landscape. Lighting is more successful than anatomical construction and purposeful detail.

Step 5 Preview

A recognizable, coherent simplification with purposeful facial contours and differentiated fingers. These provide more construction and detail than the broad silhouette alone suggests. The oversized face, frontal seated pose, unresolved wrists and sparse landscape still substantially limit likeness, depth and finish.

Score breakdown

CategoryClaude Haiku 5.5Step 5 Preview
Task & likeness3.0/104.0/10
Anatomy & construction4.0/104.0/10
Space & placement4.0/104.0/10
Light & reflections5.5/103.5/10
Purposeful detail2.5/104.0/10
Artistry & character3.5/104.0/10
Materials & effects2.5/103.0/10
Visual integrity5.5/103.5/10

Benchmark task

An SVG interpretation of the Mona Lisa tests facial likeness, anatomy and the composition of a familiar portrait.

Beach

Same task instructions

Creativity, perspective and visual beauty.

The judgment

Claude Haiku 5.5

A cheerful, coherent beach illustration with attractive sunset colors, readable accessories and clean silhouettes. Its sun and sailboat reflections establish useful physical relationships. Simple animal construction, flattened foreground placement, sparse directional shadows and minimally differentiated surfaces limit its drawing refinement.

Step 5 Preview

A recognizable sunset beach with clear warm-cool contrast and playful accessories. Basic animal construction, shallow foreground placement and schematic reflections limit spatial and physical credibility. Sparse descriptive detail and abruptly ended sky bands constrain the finish.

Score breakdown

CategoryClaude Haiku 5.5Step 5 Preview
Task & likeness8.5/104.0/10
Anatomy & construction6.5/103.0/10
Space & placement7.0/103.5/10
Light & reflections7.0/103.5/10
Purposeful detail7.0/103.0/10
Artistry & character6.0/103.0/10
Materials & effects6.0/103.5/10
Visual integrity8.5/104.0/10

Benchmark task

A busy shoreline at sunset tests scene composition, animal forms and the relationship between light and water reflections.

Ground Truth

Same task instructions

Physical reasoning, light and visual reconstruction.

The judgment

Claude Haiku 5.5

This benchmark has not been assessed yet.

Step 5 Preview

This benchmark has not been assessed yet.

Benchmark task

A plank, computer mouse and blueberry in a steel room test physical stability, spatial relationships, materials and lighting.

Raccoon

Same task instructions

Scene composition and interacting subjects.

The judgment

Claude Haiku 5.5

A tidy, appealing cartoon with recognizable animals and a pleasing sunset palette. Steering lacks visible controls, while schematic limbs and uncertain raccoon support weaken the requested interaction. Shallow vehicle construction, flat character lighting and modest displacement limit physical coherence. Clean shapes and readable identifying details remain strengths.

Step 5 Preview

Recognizable animals, a bright palette and identifying accessories support a basic cartoon. Primitive anatomy, partial seated support, unresolved steering and weak hull-water contact limit the central action. Lighting and spray provide atmosphere without establishing convincing physical depth.

Score breakdown

CategoryClaude Haiku 5.5Step 5 Preview
Task & likeness4.0/104.0/10
Anatomy & construction3.5/104.5/10
Space & placement5.5/103.0/10
Light & reflections4.0/103.5/10
Purposeful detail5.5/104.0/10
Artistry & character4.5/103.5/10
Materials & effects5.5/103.0/10
Visual integrity4.5/103.0/10

Benchmark task

A jet-ski scene pairs a canine driver with a raccoon passenger. It tests the placement and contact of interacting subjects, along with vehicle construction.

Pelican

Same task instructions

Subject construction and spatial relationships.

The judgment

Claude Haiku 5.5

A cheerful, recognizable illustration with clean contours and a balanced warm palette. Aligned wheels and readable frame geometry establish the bicycle, but shoulder construction, feet and steering contact remain imprecise. Sparse drivetrain detail, flat materials and absent grounding shadows limit anatomical and spatial conviction.

Step 5 Preview

The pelican and bicycle are recognizable, with a pleasant palette and basic diffuse shading. The riding relationship fails physically: the bird is unsupported, the front wheel is unmounted, and pedalling is unresolved. Simple geometric construction and sparse material treatment further limit the drawing.

Score breakdown

CategoryClaude Haiku 5.5Step 5 Preview
Task & likeness8.0/103.0/10
Anatomy & construction5.5/103.0/10
Space & placement6.5/103.0/10
Light & reflections5.0/103.0/10
Purposeful detail6.0/104.0/10
Artistry & character5.0/103.0/10
Materials & effects5.0/103.0/10
Visual integrity8.0/102.0/10

Benchmark task

A cycling pelican tests anatomy, riding posture and contact between the bird and the bicycle.