STEALTHMARK · HEAD TO HEAD

All comparisons ↗

Gemini 3.8 Flash vs Kimi K3.1 Pro

Kimi K3.1 Pro leads Gemini 3.8 Flash by 8.8 points on StealthMark, 56.7 to 47.9. It leads on 6 of 9 benchmarks, including both games, and Gemini 3.8 Flash on 3. Kimi K3.1 Pro scores higher on Newton's Mirror, with its largest category advantage in reflections.

See the difference ↘
All results ↗
All results ↗

Overall StealthMark

47.9/100Overall rank 20/53
56.7/100Overall rank 11/53

General Intelligence

43.9/100
53.9/100

Visual Intelligence

55.2/100
62.0/100

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

BENCHMARK BY BENCHMARK

Where each model leads

  • Gemini 3.8 Flash
  • Kimi K3.1 Pro
  • Other models
  • Median

DATASHEET

Specs and pricing

Gemini 3.8 Flash is 2.7× cheaper per output token and runs 46% faster in our speed test. Kimi K3.1 Pro scores higher on StealthMark. Both take about 1M tokens of context.

  • Gemini 3.8 Flash
  • Kimi K3.1 Pro
  • Other models
  • Median
PricePer 1M output tokens, input below
Gemini 3.8 Flash: $3.752.7× cheaper$0.75 inputKimi K3.1 Pro: $10$2 input
Context windowTokens per request, max output below
Gemini 3.8 Flash: 1MTied64K max outputKimi K3.1 Pro: 1MTied1M max output
Output speedTokens per second, our measurement
Gemini 3.8 Flash: 17046% fastertokens/sKimi K3.1 Pro: 117tokens/s
SizeTotal and active parameters
Gemini 3.8 Flash: Not disclosedKimi K3.1 Pro: 2.8T104B activeEstimated
Developer
GoogleMoonshot AI
Released
2 Sep 202623 Oct 2026
Origin
United StatesChina
Input → output
Text, image, video, audio, PDF → textText, image, video → text
Architecture
Not publishedPost-trained version of Kimi K3, a Mixture-of-Experts model

Full datasheets, every price and sourceGemini 3.8 Flash ↗Kimi K3.1 Pro ↗

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.

Gemini 3.8 Flash 45.4/100Rank 20/47

Survived 1 of 3
Foresight: complete playing field
Level 311 ptsTurn 17 / 20

Kimi K3.1 Pro 61.1/100Rank 10/47

Survived 1 of 3
Foresight: complete playing field
Level 315 ptsTurn 20 / 20

Points per level

LevelGemini 3.8 FlashKimi K3.1 Pro
Level 1Second Thoughts
4 ptsOut of lives
15 ptsOut of lives
Level 2Pressure Pot
10 ptsSurvived
12 ptsOut of lives
Level 3Hide or Flight
11 ptsOut of lives
15 ptsSurvived

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.

Gemini 3.8 Flash 72.9/100Rank 14/48

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

Kimi K3.1 Pro 81.8/100Rank 8/48

Cleared 5 of 5
Latch: complete playing field
Level 519.8 ptsTurn 31 / 40

Points per level

LevelGemini 3.8 FlashKimi K3.1 Pro
Level 1Hold the door
5.2 ptsCleared
5.2 ptsCleared
Level 2Crossfeed
9.8 ptsCleared
9.8 ptsCleared
Level 3Relay vault
18.8 ptsCleared
19.2 ptsCleared
Level 4Passing bay
17.8 ptsClearedFinished early · 1 beacon left
18.2 ptsClearedFinished early · 3 beacons left
Level 5Second thoughts
20.6 ptsCleared
19.8 ptsCleared

Newton's Mirror

Same task instructions

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

The judgment

Gemini 3.8 Flash

Crimson is carried well down the camera-facing surface, supporting its earlier interaction. The depiction remains highly simplified, with imperfect material rendering. Isolated wall and floor images and a few highlights provide scant reflective evidence; displaced first reflections, missing receding chains and absent nested sphere and emitter imagery leave the room's optical structure largely unsupported.

Kimi K3.1 Pro

The settled sphere, separate airborne black paint and crimson-before-cyan interaction are supported, with a modest crimson travel overshoot. A shared downward framing displacement remains after accounting for the square canvas. The principal limitation is the reflection system: sparse sphere copies and generic curved bands omit most of the ordered mirror-room structure. Materials receive a small upward revision because bounded bright images and dark bands visibly establish some polish, while soft shading and bulky paint remain separate weaknesses.

Score breakdown

CategoryGemini 3.8 FlashKimi K3.1 Pro
State at 600 ms22.5/2523.5/25
Camera and placement11.0/1510.5/15
Reflections4.5/12026.0/120
Materials and scale7.0/107.0/10
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

Gemini 3.8 Flash

The dominant four-point silhouette, luminous color progression, raised brows and enormous grin closely fulfill the brief. Attached, secondary limbs support the exuberant expression. Clean facial drawing and glossy eyes give strong character, while shallow depth, minimally articulated extremities and visible steps in the outer glow limit refinement.

Kimi K3.1 Pro

The transformed reflection, attentive pose and constellation anatomy clearly communicate introspection. Purposeful fine details enrich a coherent composition. Tubular limbs, crowded lower-body overlaps, shallow depth and limited cast lighting keep the overall execution within the competent range.

Score breakdown

CategoryGemini 3.8 FlashKimi K3.1 Pro
Task & likeness8.0/108.0/10
Anatomy & construction6.0/105.5/10
Space & placement6.5/106.5/10
Light & reflections7.0/106.5/10
Purposeful detail5.0/107.5/10
Artistry & character3.5/107.0/10
Materials & effects5.0/107.0/10
Visual integrity6.5/107.0/10

Benchmark task

Gemini 3.8 Flash

A luminous star-shaped creature tests expressive features, a clear silhouette and smooth colour transitions.

Kimi K3.1 Pro

An imagined creature encounters its reflection. The scene tests original character design, visual self-interpretation and the relationship between a subject and its reflected image.

Mona Lisa

Same task instructions

Precise visual recall and portrait reconstruction.

The judgment

Gemini 3.8 Flash

The dark clothing, overlapping hands and hazy landscape make the Mona Lisa reference recognizable. Replication is limited by the frontal, elongated face, heavy mouth and chin, and poorly resolved hands, wrists and forearm. Soft shading gives some volume, but muddy transitions, blunt landscape shapes and rigid facial modeling weaken the portrait’s expression and painterly character.

Kimi K3.1 Pro

A coherent, recognizable interpretation with controlled color and readable landscape layers. Replication is limited by the frontal seated construction, elongated facial proportions and oversized, weakly articulated hands. Smooth shading supplies some volume but little of the reference's subtle expression, fabric structure or atmospheric transitions.

Score breakdown

CategoryGemini 3.8 FlashKimi K3.1 Pro
Task & likeness3.0/105.0/10
Anatomy & construction2.0/105.0/10
Space & placement3.5/105.5/10
Light & reflections3.0/106.0/10
Purposeful detail5.0/105.5/10
Artistry & character3.0/106.0/10
Materials & effects5.0/105.0/10
Visual integrity1.0/106.5/10

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

Gemini 3.8 Flash

A vivid purple-and-gold sunset anchors an appealing beach composition with dolphins, birds, a turtle and playful accessories. Palm silhouettes frame the bright reflection effectively. Sparse animal anatomy, wirelike palm foliage, conspicuously regular reflection bands and limited surface texture keep the execution below exceptional.

Kimi K3.1 Pro

A coherent, playful beach illustration with readable animals, an organized composition and an aligned sunset reflection. Connected silhouettes, sand texture and atmospheric effects demonstrate controlled execution. Simplified joints, flattened foreground viewpoints and inconsistent shadows limit anatomical and spatial credibility.

Score breakdown

CategoryGemini 3.8 FlashKimi K3.1 Pro
Task & likeness9.0/108.5/10
Anatomy & construction7.0/105.5/10
Space & placement7.0/105.5/10
Light & reflections8.0/106.5/10
Purposeful detail7.0/106.5/10
Artistry & character7.0/105.5/10
Materials & effects7.0/106.5/10
Visual integrity8.0/107.5/10

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

Gemini 3.8 Flash

This benchmark has not been assessed yet.

Kimi K3.1 Pro

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

Gemini 3.8 Flash

Expressive animals, a bold diagonal hull and sweeping spray create an appealing action scene. The raccoon's support on the dog's back is unclear, and the dog lacks a readable paw-to-control grip and connected steering assembly. Clean graphic shapes and lively accessories are stronger than the anatomical construction. Sunset illumination and reflections remain largely decorative.

Kimi K3.1 Pro

The additional comparisons support retaining the assessment. Readable steering, shaped animal contours and purposeful details coexist with simplified joints, a frontal passenger whose seated weight is weakly conveyed, and limited physical lighting. The angled craft establishes more depth than the riding pose resolves.

Score breakdown

CategoryGemini 3.8 FlashKimi K3.1 Pro
Task & likeness7.0/107.0/10
Anatomy & construction6.0/105.5/10
Space & placement7.0/106.0/10
Light & reflections6.5/105.5/10
Purposeful detail7.5/107.0/10
Artistry & character7.5/106.0/10
Materials & effects7.5/106.0/10
Visual integrity7.5/107.0/10

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

Gemini 3.8 Flash

The pelican’s enormous bill, lively feathers and orange bicycle create a clear, appealing composition. Basket contents, spokes and facial details reward inspection. Both legs connect to the body, but foot-to-pedal placement and wing-to-handlebar contact are ambiguous. Bicycle mechanics and lighting remain schematic, limiting an otherwise polished illustration.

Kimi K3.1 Pro

A characterful coastal illustration with controlled contours and varied feather, accessory and bicycle detail. Layered scenery and subtle shading enrich the presentation. Soft leg articulation, unresolved riding contacts, shallow depth and generalized lighting limit physical precision.

Score breakdown

CategoryGemini 3.8 FlashKimi K3.1 Pro
Task & likeness9.0/108.5/10
Anatomy & construction7.5/107.5/10
Space & placement7.5/106.5/10
Light & reflections7.0/106.5/10
Purposeful detail8.5/107.5/10
Artistry & character8.0/107.5/10
Materials & effects7.0/106.5/10
Visual integrity8.0/107.5/10

Benchmark task

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