STEALTHMARK · HEAD TO HEAD

All comparisons ↗

GPT-5.5 vs GPT-6.1 Terra Low

GPT-6.1 Terra Low leads GPT-5.5 by 4.8 points on StealthMark, 41.3 to 36.5. It leads on 7 of 9 benchmarks, including Foresight, and GPT-5.5 on 2, including Latch. GPT-6.1 Terra Low scores higher on Mona Lisa, with its largest category advantage in anatomy & construction.

See the difference ↘
All results ↗
All results ↗

Overall StealthMark

36.5/100Overall rank 40/55
41.3/100Overall rank 35/55

General Intelligence

36.6/100
34.3/100

Visual Intelligence

36.3/100
53.1/100

BENCHMARK BY BENCHMARK

Where each model leads

  • GPT-5.5
  • GPT-6.1 Terra Low
  • Other models
  • Median

DATASHEET

Specs and pricing

  • GPT-5.5
  • GPT-6.1 Terra Low
  • Other models
  • Median
PricePer 1M output tokens, input below
GPT-5.5: $30$5 inputGPT-6.1 Terra Low: No list price
Context windowTokens per request, max output below
GPT-5.5: 1.05M128K max outputGPT-6.1 Terra Low: Not published
Output speedTokens per second, our measurement
GPT-5.5: 193tokens/sGPT-6.1 Terra Low: Not measured
Developer
OpenAINot published
Released
23 Apr 2026Not published
Origin
United StatesNot published
Input → output
Text, image → textNot published

Full datasheets, every price and sourceGPT-5.5 ↗

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.

GPT-5.5 38.7/100Rank 37/512 of 3 levels

2 of 3 played
Foresight: complete playing field
Level 25 ptsTurn 9 / 18

GPT-6.1 Terra Low 36.1/100Rank 26/51

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

Points per level

LevelGPT-5.5GPT-6.1 Terra Low
Level 1Second Thoughts
17 ptsOut of lives
4 ptsOut of lives
Level 2Pressure Pot
5 ptsOut of lives
8 ptsOut of lives
Level 3Hide or Flight
Not played
9 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.

GPT-5.5 71.7/100Rank 17/52

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

GPT-6.1 Terra Low 62.4/100Rank 23/52

Cleared 4 of 5
Latch: complete playing field
Level 520.6 ptsTurn 27 / 40

Points per level

LevelGPT-5.5GPT-6.1 Terra Low
Level 1Hold the door
5.2 ptsCleared
5.2 ptsCleared
Level 2Crossfeed
9.8 ptsCleared
9.2 ptsCleared
Level 3Relay vault
18.8 ptsCleared
18.8 ptsCleared
Level 4Passing bay
17.2 ptsClearedFinished early · 1 beacon left
10.2 ptsFinished early
Level 5Second thoughts
20.6 ptsCleared
20.6 ptsCleared

Newton's Mirror

Same task instructions

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

The judgment

GPT-5.5

The paint ordering and separate black bead support part of the physical state, but adhesion and rotational transport remain only partly established. The sweeping cyan arc and long crimson lobes do not clearly communicate the limited time since their respective impacts. The main sphere is too large and too low, and the black bead is below its required projected position. Displaced isolated sphere images, a flattened floor echo and missing recursive, nested and emitter reflections provide little coherent optical structure. The colored paint is excessively bulky for the specified quantities.

GPT-6.1 Terra Low

Deformed colored paint and a separate airborne black body establish readable interaction history. Cyan has travelled too far, framing differs substantially, and the mirror system supplies only elementary bands and oval copies. Missing recursive geometry, nested spherical imagery and emitter mapping remain the dominant weaknesses.

Score breakdown

CategoryGPT-5.5GPT-6.1 Terra Low
State at 600 ms15.0/2522.0/25
Camera and placement6.0/154.0/15
Reflections5.0/12010.0/120
Materials and scale6.0/106.0/10
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

Same task instructions

Visual construction and creative interpretation.

The judgment

GPT-5.5

Six pale, scaled lobes form a balanced radial arrangement, but they remain separate capsules rather than an interlocking serpent knot. There are no crossings, alternating overlaps, or crisp inner bends; the central hexagon is an isolated outline. Small outward-facing heads sit within the lobes without integrated necks. Soft shading and tidy contours provide some finish, while repetitive oval scales and cartoon faces limit organic credibility.

GPT-6.1 Terra Low

Six attached outward-facing heads, delicate scales and soft ivory shading establish an orderly decorative motif. Separate paddle-shaped bodies replace the required interlocking loops and leave no enclosed central hexagon. Surface detail provides interest, but repeated simple forms, schematic faces and limited anatomical modeling constrain the result.

Score breakdown

CategoryGPT-5.5GPT-6.1 Terra Low
Task & likeness3.0/104.0/10
Anatomy & construction3.0/103.5/10
Space & placement5.0/104.5/10
Light & reflections5.0/105.5/10
Purposeful detail4.5/105.5/10
Artistry & character4.0/105.0/10
Materials & effects4.5/105.5/10
Visual integrity7.0/104.0/10

Benchmark task

A pale serpent woven into an interlocking knot tests connected anatomy, repeated structure and readable overlaps. Organic surface detail must work with the overall geometry.

Mona Lisa

Same task instructions

Precise visual recall and portrait reconstruction.

The judgment

GPT-5.5

The veil, restrained smile, crossed hands and muted landscape establish Mona Lisa references. The oversized frontal face and schematic features weaken likeness and expression, while fingerless tapered hand shapes leave anatomy unresolved. Clean contours and balanced framing provide coherence, but sparse garment detail, broad landscape bands and shallow shading limit the portrait's sophistication.

GPT-6.1 Terra Low

A recognizable, coherent portrait with purposeful facial detail, warm local volume and layered scenery. The frontal pose, enlarged face, merged hands and shallow clothing construction substantially limit replication and drawing skill. The visible successes support retaining the current assessment.

Score breakdown

CategoryGPT-5.5GPT-6.1 Terra Low
Task & likeness1.5/105.0/10
Anatomy & construction1.5/104.5/10
Space & placement1.5/105.0/10
Light & reflections2.0/106.0/10
Purposeful detail2.5/105.0/10
Artistry & character1.5/105.5/10
Materials & effects2.0/105.0/10
Visual integrity1.5/106.0/10

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

GPT-5.5

The sunset, palms, birds, playful animals and ball clearly establish the requested beach scene. Warm sky gradients and clean silhouettes make it appealing. Animal construction is underdeveloped: torso and limb connections are unclear, especially in the round-eared foreground figure. The dolphin lacks a convincing splash, and broad reflection bands suggest sunset light without resolving its behavior on water.

GPT-6.1 Terra Low

A coherent sunset scene demonstrates the beach, animals, birds and reflections. Flowing silhouettes, warm color transitions and intact attachments are its strongest properties. Simplified anatomy, the turtle's elevated viewing angle and symbolic surface effects constrain drawing complexity and physical depth.

Score breakdown

CategoryGPT-5.5GPT-6.1 Terra Low
Task & likeness7.0/108.0/10
Anatomy & construction2.5/105.5/10
Space & placement3.0/105.5/10
Light & reflections3.0/106.5/10
Purposeful detail3.0/106.0/10
Artistry & character3.0/105.0/10
Materials & effects3.0/105.5/10
Visual integrity3.5/107.5/10

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

GPT-5.5

This benchmark has not been assessed yet.

GPT-6.1 Terra Low

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

GPT-5.5

The raccoon's masked face, bright hull and sweeping wake make the scene readable and lively. The dog is much less resolved: its head is ambiguous, overlapping brown forms obscure its anatomy, and its paws do not visibly grip the controls. Smooth shapes and cheerful colors provide appeal, but weak steering construction and limited depth keep the drawing uneven.

GPT-6.1 Terra Low

Recognizable animals, a coherent craft and sweeping wake make an appealing cartoon. Basic limb construction, weakly demonstrated raccoon seating and limited shared perspective constrain the scene. Small identifying details work well, while lighting and materials remain broadly graphic.

Score breakdown

CategoryGPT-5.5GPT-6.1 Terra Low
Task & likeness3.5/106.5/10
Anatomy & construction3.0/105.0/10
Space & placement4.5/105.5/10
Light & reflections5.0/104.5/10
Purposeful detail3.5/106.0/10
Artistry & character3.0/105.0/10
Materials & effects5.0/105.0/10
Visual integrity3.0/106.0/10

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

GPT-5.5

The oversized bill, bright bicycle and sunset create an appealing, recognizable cartoon. Riding mechanics are less convincing: the wing has no clear steering contact, leg attachments are uneven, and feet do not visibly engage pedals. A dark notch complicates the rear neck junction. Clean contours and orderly spokes provide polish, while simplified anatomy and lighting limit depth.

GPT-6.1 Terra Low

A coherent coastal illustration with a distinctive pelican, controlled contours and clearly organised bicycle wheels. Visible saddle support and shaped neck and wing contours earn credit beyond basic geometric construction. Rubbery legs, unresolved pedal contacts and absent steering contact limit the riding action. Lighting and materials remain restrained and spatially shallow.

Score breakdown

CategoryGPT-5.5GPT-6.1 Terra Low
Task & likeness7.5/107.0/10
Anatomy & construction4.5/105.5/10
Space & placement6.5/106.0/10
Light & reflections6.5/105.5/10
Purposeful detail5.5/106.5/10
Artistry & character5.0/106.0/10
Materials & effects6.0/106.0/10
Visual integrity7.5/106.0/10

Benchmark task

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