STEALTHMARK · HEAD TO HEAD

All comparisons ↗

Claude Opus 5.5 vs DeepSeek-V4.1-Flash-1017

Claude Opus 5.5 leads DeepSeek-V4.1-Flash-1017 by 13.4 points on StealthMark, 72.6 to 59.2. It leads on all 9 benchmarks. Claude Opus 5.5 scores higher on Newton's Mirror, with its largest category advantage in reflections.

See the difference ↘
All results ↗
All results ↗

Overall StealthMark

72.6/100Overall rank 2/53
59.2/100Overall rank 9/53

General Intelligence

71.3/100
56.8/100

Visual Intelligence

75.0/100
63.5/100

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 Opus 5.5

Open or local

Open modelMIT

BENCHMARK BY BENCHMARK

Where each model leads

  • Claude Opus 5.5
  • DeepSeek-V4.1-Flash-1017
  • Other models
  • Median

DATASHEET

Specs and pricing

Claude Opus 5.5 scores higher on StealthMark. DeepSeek-V4.1-Flash-1017 is 17× cheaper per output token and runs 1.9× faster in our speed test. Both take about 1M tokens of context.

  • Claude Opus 5.5
  • DeepSeek-V4.1-Flash-1017
  • Other models
  • Median
PricePer 1M output tokens, input below
Claude Opus 5.5: $20$4 inputDeepSeek-V4.1-Flash-1017: $1.2017× cheaper$0.30 input
Context windowTokens per request, max output below
Claude Opus 5.5: 1MTied128K max outputDeepSeek-V4.1-Flash-1017: 1MTied384K max output
Output speedTokens per second, our measurement
Claude Opus 5.5: 166tokens/sDeepSeek-V4.1-Flash-1017: 3101.9× fastertokens/s
SizeTotal and active parameters
Claude Opus 5.5: Not disclosedDeepSeek-V4.1-Flash-1017: 763B16B activeEstimated
Developer
AnthropicDeepSeek-AI
Released
22 Sep 202617 Oct 2026
Origin
United StatesChina
Input → output
Text, image → textBoth
Architecture
Not publishedSparse mixture-of-experts with a causal encoder-decoder design and native image understanding.

Full datasheets, every price and sourceClaude Opus 5.5 ↗DeepSeek-V4.1-Flash-1017 ↗

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 Opus 5.5 66.3/100Rank 5/47

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

DeepSeek-V4.1-Flash-1017 52.9/100Rank 15/47

Survived 1 of 3
Foresight: complete playing field
Level 310 ptsTurn 15 / 20

Points per level

LevelClaude Opus 5.5DeepSeek-V4.1-Flash-1017
Level 1Second Thoughts
27 ptsSurvived
26 ptsSurvived
Level 2Pressure Pot
11 ptsSurvived
7 ptsOut of lives
Level 3Hide or Flight
9 ptsSurvived
10 ptsOut of lives

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 Opus 5.5 87.6/100Rank 1/48

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

DeepSeek-V4.1-Flash-1017 73.9/100Rank 13/48

Cleared 5 of 5
Latch: complete playing field
Level 520 ptsTurn 30 / 40

Points per level

LevelClaude Opus 5.5DeepSeek-V4.1-Flash-1017
Level 1Hold the door
5.2 ptsCleared
5.2 ptsCleared
Level 2Crossfeed
10.2 ptsClearedFinished early · 1 beacon left
9.8 ptsCleared
Level 3Relay vault
19.2 ptsCleared
19.2 ptsCleared
Level 4Passing bay
18.2 ptsClearedFinished early · 3 beacons left
16.4 ptsClearedFinished early · 3 beacons left
Level 5Second thoughts
20.6 ptsCleared
20 ptsCleared

Newton's Mirror

Same task instructions

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

The judgment

Claude Opus 5.5

Open lateral sightlines, first reflected silhouettes and near-field planar panel placement are convincing. Missing outer chains, truncated repetitions and absent nested spherical room and emitter imagery remain the main weaknesses.

DeepSeek-V4.1-Flash-1017

Principal sphere and airborne-black placements are supported, and diminishing bilateral chains provide limited optical structure. Missing nested imagery, incomplete outer chains, distorted first images and sparse emitter recurrence remain the dominant weaknesses. Oversized paint bodies and unresolved cyan contact impose separate limitations.

Score breakdown

CategoryClaude Opus 5.5DeepSeek-V4.1-Flash-1017
State at 600 ms24.0/2523.0/25
Camera and placement15.0/1513.5/15
Reflections55.0/12034.0/120
Materials and scale9.0/108.5/10
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 Opus 5.5

The centered coral squid has a friendly, restrained expression and a balanced radial silhouette within a cream arch. Smooth curves and soft shading give it an appealing matte finish. The mantle is more elongated than compact, the upper arms are visually ambiguous, and the two hanging tentacles read somewhat like legs. Clean execution supports a strong stylized illustration.

DeepSeek-V4.1-Flash-1017

An expressive, intricately drawn storybook scene with a complete flowing silhouette and differentiated glossy materials. The supported main lens and continuous shrimp body make the central interaction readable, but reciprocal eye lines, facial magnification and the smaller lens grip remain ambiguous. Bright granular fringes and crowded accessory lines limit the finish.

Score breakdown

CategoryClaude Opus 5.5DeepSeek-V4.1-Flash-1017
Task & likeness8.0/107.5/10
Anatomy & construction7.5/107.5/10
Space & placement8.0/108.0/10
Light & reflections7.5/107.0/10
Purposeful detail7.0/107.5/10
Artistry & character7.0/108.0/10
Materials & effects7.0/107.5/10
Visual integrity8.5/106.5/10

Benchmark task

Claude Opus 5.5

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

DeepSeek-V4.1-Flash-1017

A whale and a tiny shrimp examine one another through bubble lenses, with an octopus nearby. The scene tests interacting characters, differences in scale and transparent materials.

Mona Lisa

Different task instructions

Precise visual recall and portrait reconstruction.

The judgment

Claude Opus 5.5

The portrait preserves the recognizable composition, dark veil, folded hands and distant landscape. Replication is limited by the elongated face and neck, conspicuous eyes and simplified smile. Hands remain connected but their rounded fingers and wrists lack convincing anatomy. Restrained colors create cohesion; shallow modeling and pervasive mottling weaken volume and painterly subtlety.

DeepSeek-V4.1-Flash-1017

A coherent graphic interpretation with controlled contours, modeled facial volume and purposeful portrait details. Replication remains limited by the frontal pose, enlarged face, altered expression and ambiguous crossed hands. Landscape layering provides depth, while schematic fabric, smooth surfaces and tonal bands constrain the finish.

Score breakdown

CategoryClaude Opus 5.5DeepSeek-V4.1-Flash-1017
Task & likeness6.5/105.0/10
Anatomy & construction5.5/105.0/10
Space & placement6.5/106.0/10
Light & reflections6.5/106.0/10
Purposeful detail6.5/105.5/10
Artistry & character6.0/105.5/10
Materials & effects7.0/105.5/10
Visual integrity7.0/106.0/10

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 Opus 5.5

A lively, well-composed beach illustration with rich sunset colors, recognizable animals and appealing accessories. The sun reflection establishes a strong central focus. Clean silhouettes and small details reward inspection, though simplified animal construction, uneven contact shadows and mostly flat materials limit depth and realism.

DeepSeek-V4.1-Flash-1017

A coherent, colorful beach illustration with controlled curves, clean layering and varied readable accessories. Castle details and small animal features strengthen its finish. Schematic airborne animals, uncertain board support, shallow architectural depth and decorative reflections limit physical coherence and drawing sophistication.

Score breakdown

CategoryClaude Opus 5.5DeepSeek-V4.1-Flash-1017
Task & likeness8.5/107.0/10
Anatomy & construction7.5/105.5/10
Space & placement7.0/105.5/10
Light & reflections7.5/106.0/10
Purposeful detail7.5/106.5/10
Artistry & character8.0/105.0/10
Materials & effects6.5/105.5/10
Visual integrity8.0/104.5/10

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 Opus 5.5

This benchmark has not been assessed yet.

DeepSeek-V4.1-Flash-1017

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

Different task instructions

Scene composition and interacting subjects.

The judgment

Claude Opus 5.5

The masked raccoon clearly rides the dog's back, and the dog's forward paw reaches the steering grip. Expressive faces, vivid colors and sweeping wakes create an appealing illustration. Connected limbs remain schematic, as does the small steering assembly. The broad hull and flat foam weaken water contact; the glowing sun lacks a corresponding reflection or convincing cast shadows.

DeepSeek-V4.1-Flash-1017

An appealing cartoon with recognizable riders, expressive faces and a cohesive twilight palette. Clean shapes support the composition, but ambiguous limb overlaps, weak seat contact and loosely resolved steering limit physical coherence. Lighting and water effects are decorative, with modest material differentiation and drawing complexity.

Score breakdown

CategoryClaude Opus 5.5DeepSeek-V4.1-Flash-1017
Task & likeness8.5/108.0/10
Anatomy & construction7.5/107.0/10
Space & placement7.5/107.0/10
Light & reflections6.0/106.5/10
Purposeful detail8.5/107.0/10
Artistry & character7.0/107.0/10
Materials & effects7.0/106.5/10
Visual integrity8.0/108.0/10

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 Opus 5.5

The recognizable pelican, orderly bicycle wheels and harmonious sunset create an appealing illustration. Both legs connect to the body and reach pedals; no clear detached or inverted parts appear. Steering contact and seating support are less convincing, while the drivetrain remains schematic. Crisp outlines give a clean finish, but limited shading and flat surfaces leave the scene with modest depth.

DeepSeek-V4.1-Flash-1017

An expressive, controlled illustration with continuous body construction, substantial bicycle detail and effective landscape depth. Unclear foot-to-pedal and wing-to-handlebar contacts limit physical conviction and local readability. Purposeful detail and composition are stronger than directional lighting and material treatment.

Score breakdown

CategoryClaude Opus 5.5DeepSeek-V4.1-Flash-1017
Task & likeness8.5/108.5/10
Anatomy & construction8.0/107.0/10
Space & placement7.0/107.5/10
Light & reflections6.0/106.5/10
Purposeful detail8.0/107.5/10
Artistry & character7.5/107.0/10
Materials & effects6.0/107.0/10
Visual integrity8.5/107.5/10

Benchmark task

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