GPT-5.3-Codex vs Inkling Small
Updated October 21, 2026. 13 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.
Decision reading
GPT-5.3-Codex and Inkling Small are level for coding, 29.5 against 29.9 on the Vibe Coding Index, so price and context decide.
Pick GPT-5.3-Codex when what matters is LiveCodeBench (Vals AI) or Vibe Code Bench (Vals AI), where it leads. Pick Inkling Small when output tokens cost 11.7x less, or when a solved task costs $0.16 against $0.59.
- Shared results
- 13
- GPT-5.3-Codex only
- 21
- Inkling Small only
- 71
- Like-for-like categories
- 4 of 9
Shared results can support a head-to-head reading. Results only one model has describe coverage, not superiority.
Which one for your work
Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.
Coding
Vibe Coding Index, four public coding benchmarks
No call
Level: 29.5 against 29.9, inside 2 points.
One benchmark behind each score
Intelligence
AA Intelligence Index
GPT-5.3-Codex
GPT-5.3-Codex leads, 32.5 against 25.7.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Inkling Small has a AA Agentic Index result, 23.5.
Directional only
Reasoning
GPQA Diamond
No call
Only Inkling Small has a GPQA Diamond result, 83.6%.
Directional only
Knowledge
MMLU Pro
No call
Only Inkling Small has a MMLU Pro result, 85.6%.
Directional only
Web design
Design Arena: websites
No call
Only GPT-5.3-Codex has a Design Arena: websites result, 1163.
Directional only
General
Vals Index
No call
Only Inkling Small has a Vals Index result, 27.6%.
Directional only
Long documents
Listed context window
Inkling Small
Inkling Small takes 524K tokens against 400K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Inkling Small
GPT-5.3-Codex $0.0088, Inkling Small $0.0010 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
Inkling Small
GPT-5.3-Codex $0.59, Inkling Small $0.16.
Published attempt cost and pass rate
At a glance
- Coding index
- GPT-5.3-Codex 29.5 from 1 benchmark, Inkling Small 29.9 from 1 benchmark.
- Widest category
- Coding, 12.9 points apart on average over 8 shared benchmarks.
- Widest single gap
- IOI (Vals AI): GPT-5.3-Codex 53.8% against Inkling Small 9.3%, 44.5 points apart on a 0 to 100 scale.
- Output price
- GPT-5.3-Codex $14.00 against Inkling Small $1.20 per million output tokens, 11.7x apart.
- Context window
- GPT-5.3-Codex takes 400K tokens, Inkling Small 524K.
Benchmark by benchmark
First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.
| Category | GPT-5.3-Codex | Bars | Inkling Small | Ties |
|---|---|---|---|---|
| Coding | 5 | 3 | ||
| Intelligence | 2 | 0 | ||
| Reasoning | 2 | 0 | ||
| General | 1 | 0 | ||
| All shared boards | 10 | 3 |
CodingLike-for-likeFour of these boards feed the Vibe Coding Index53
| Benchmark | GPT-5.3-Codex | Inkling Small | Leader |
|---|---|---|---|
| LMArena WebDev | 1407 | 1409 | Inkling Small |
| AA Coding Index | Not measured | 52.9 | Only Inkling Small measured |
| LiveCodeBench (Vals AI) | 87.3% | 85.9% | GPT-5.3-Codex |
| SWE-bench Verified (Vals AI) | 78.0% | 82.2% | Inkling Small |
| Terminal-Bench 4 (Vals AI) | Not measured | 0.0% | Only Inkling Small measured |
| Vibe Code Bench (Vals AI) | 61.8% | 19.1% | GPT-5.3-Codex |
| Code migration (Vals AI) | Not measured | 13.7% | Only Inkling Small measured |
| ProgramBench (Vals AI) | Not measured | 0.5% | Only Inkling Small measured |
| IOI (Vals AI) | 53.8% | 9.3% | GPT-5.3-Codex |
| Terminal-Bench 2.1 (Vals AI) | Not measured | 55.1% | Only Inkling Small measured |
| SkillsBench (Vals AI) | Not measured | 33.6% | Only Inkling Small measured |
| CyberBench (Vals AI) | Not measured | 64.1% | Only Inkling Small measured |
| SciCode | Not measured | 49.7% | Only Inkling Small measured |
| Terminal-Bench Hard (Artificial Analysis run) | 53.0% | Not measured | Only GPT-5.3-Codex measured |
| Terminal-Bench | 78.4% | Not measured | Only GPT-5.3-Codex measured |
| WeirdML | 79.3% | Not measured | Only GPT-5.3-Codex measured |
| ALE-Bench | 1655.2 | Not measured | Only GPT-5.3-Codex measured |
| LMArena Text: coding | Not measured | 1450 | Only Inkling Small measured |
| LMArena Text: software and IT | Not measured | 1447 | Only Inkling Small measured |
| LMArena WebDev: React | 1395 | 1399 | Inkling Small |
| LMArena WebDev: HTML | 1422 | 1398 | GPT-5.3-Codex |
| LMArena WebDev: from an image | 1443 | 1410 | GPT-5.3-Codex |
| Neither model has a result on the other 16 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | GPT-5.3-Codex | Inkling Small | Leader |
|---|---|---|---|
| AA Intelligence Index | 32.5 | 25.7 | GPT-5.3-Codex |
| Epoch Capabilities Index | 157.1 | 150.3 | GPT-5.3-Codex |
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index14 boards, none shared
| Benchmark | GPT-5.3-Codex | Inkling Small | Leader |
|---|---|---|---|
| AA Agentic Index | Not measured | 23.5 | Only Inkling Small measured |
| Design Arena: agents building web apps | 1033 | Not measured | Only GPT-5.3-Codex measured |
| Design Arena: agents building full-stack apps | 983 | Not measured | Only GPT-5.3-Codex measured |
| Design Arena: agents building mobile apps | 1054 | Not measured | Only GPT-5.3-Codex measured |
| Design Arena: agents building Android apps | 1084 | Not measured | Only GPT-5.3-Codex measured |
| Design Arena: agents building Godot games | 1124 | Not measured | Only GPT-5.3-Codex measured |
| Finance Agent (Vals AI) | Not measured | 41.3% | Only Inkling Small measured |
| Tax Agent Bench (Vals AI) | Not measured | 15.4% | Only Inkling Small measured |
| Legal Research Bench (Vals AI) | Not measured | 25.5% | Only Inkling Small measured |
| Harvey's Legal Agent Benchmark (Vals AI) | Not measured | 2.9% | Only Inkling Small measured |
| Excel Modeling Benchmark (Vals AI) | Not measured | 31.8% | Only Inkling Small measured |
| τ²-Bench Telecom | 86.0% | Not measured | Only GPT-5.3-Codex measured |
| METR time horizons | 74.5% | Not measured | Only GPT-5.3-Codex measured |
| Vending-Bench 2 | $5,940 | Not measured | Only GPT-5.3-Codex measured |
| Neither model has a result on the other 25 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | GPT-5.3-Codex | Inkling Small | Leader |
|---|---|---|---|
| GPQA Diamond | Not measured | 83.6% | Only Inkling Small measured |
| GPQA Diamond (Artificial Analysis run) | 91.5% | 89.5% | GPT-5.3-Codex |
| Humanity's Last Exam (Artificial Analysis run) | 42.5% | 33.3% | GPT-5.3-Codex |
| GPQA Diamond (Epoch AI run) | Not measured | 88.5% | Only Inkling Small measured |
| ARC-AGI | Not measured | 84.0% | Only Inkling Small measured |
| ARC-AGI-2 | Not measured | 40.1% | Only Inkling Small measured |
| Mystery game puzzles | Not measured | 6.0% | Only Inkling Small measured |
| LMArena Text: hard prompts | Not measured | 1423 | Only Inkling Small measured |
| LMArena Text: expert | Not measured | 1441 | Only Inkling Small measured |
| LMArena Text: hard prompts in English | Not measured | 1429 | Only Inkling Small measured |
| LMArena Vision: diagrams | Not measured | 1251 | Only Inkling Small measured |
| LMArena Vision: homework | Not measured | 1257 | Only Inkling Small measured |
| Neither model has a result on the other 9 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index6 boards, none shared
| Benchmark | GPT-5.3-Codex | Inkling Small | Leader |
|---|---|---|---|
| OTIS Mock AIME | Not measured | 90.0% | Only Inkling Small measured |
| FrontierMath, tiers 1 to 3 | Not measured | 46.3% | Only Inkling Small measured |
| FrontierMath, tier 4 | Not measured | 17.1% | Only Inkling Small measured |
| ProofBench | Not measured | 6.0% | Only Inkling Small measured |
| LMArena Text: math | Not measured | 1459 | Only Inkling Small measured |
| LMArena Text: mathematical work | Not measured | 1441 | Only Inkling Small measured |
| Neither model has a result on the other 7 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index11 boards, none shared
| Benchmark | GPT-5.3-Codex | Inkling Small | Leader |
|---|---|---|---|
| MMLU Pro | Not measured | 85.6% | Only Inkling Small measured |
| LegalBench (Vals AI) | Not measured | 83.0% | Only Inkling Small measured |
| CorpFin (Vals AI) | Not measured | 69.6% | Only Inkling Small measured |
| TaxEval (Vals AI) | Not measured | 75.5% | Only Inkling Small measured |
| MortgageTax (Vals AI) | Not measured | 62.3% | Only Inkling Small measured |
| MedCode (Vals AI) | Not measured | 37.9% | Only Inkling Small measured |
| SimpleQA Verified | Not measured | 19.1% | Only Inkling Small measured |
| LMArena Text: science | Not measured | 1428 | Only Inkling Small measured |
| LMArena Text: medicine and healthcare | Not measured | 1413 | Only Inkling Small measured |
| LMArena Text: legal and government | Not measured | 1415 | Only Inkling Small measured |
| LMArena Text: business and finance | Not measured | 1413 | Only Inkling Small measured |
| Neither model has a result on the other 6 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index8 boards, none shared
| Benchmark | GPT-5.3-Codex | Inkling Small | Leader |
|---|---|---|---|
| Design Arena: websites | 1163 | Not measured | Only GPT-5.3-Codex measured |
| Design Arena: UI components | 1137 | Not measured | Only GPT-5.3-Codex measured |
| Design Arena: game dev | 1162 | Not measured | Only GPT-5.3-Codex measured |
| Design Arena: data viz | 1164 | Not measured | Only GPT-5.3-Codex measured |
| Design Arena: 3D | 1008 | Not measured | Only GPT-5.3-Codex measured |
| Design Arena: all code categories | 1145 | Not measured | Only GPT-5.3-Codex measured |
| Design Arena: SVG | 1129 | Not measured | Only GPT-5.3-Codex measured |
| Design Arena: ASCII art | 1151 | Not measured | Only GPT-5.3-Codex measured |
| Neither model has a result on the other 1 board here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | GPT-5.3-Codex | Inkling Small | Leader |
|---|---|---|---|
| Vals Index | Not measured | 27.6% | Only Inkling Small measured |
| Public Benefits Bench (Vals AI) | Not measured | 59.4% | Only Inkling Small measured |
| SAGE (Vals AI) | Not measured | 32.7% | Only Inkling Small measured |
| MedScribe (Vals AI) | Not measured | 84.1% | Only Inkling Small measured |
| Vals Multimodal Index | Not measured | 50.0% | Only Inkling Small measured |
| IFBench | 75.4% | Not measured | Only GPT-5.3-Codex measured |
| Long context reasoning (AA-LCR) | 83.3% | 75.7% | GPT-5.3-Codex |
| LMArena Text | Not measured | 1413 | Only Inkling Small measured |
| LMArena Text: instruction following | Not measured | 1399 | Only Inkling Small measured |
| LMArena Text: creative writing | Not measured | 1334 | Only Inkling Small measured |
| LMArena Vision | Not measured | 1237 | Only Inkling Small measured |
| LMArena Text: English | Not measured | 1421 | Only Inkling Small measured |
| LMArena Text: non-English | Not measured | 1401 | Only Inkling Small measured |
| LMArena Text: Chinese | Not measured | 1464 | Only Inkling Small measured |
| LMArena Text: German | Not measured | 1408 | Only Inkling Small measured |
| LMArena Text: Japanese | Not measured | 1401 | Only Inkling Small measured |
| LMArena Text: Korean | Not measured | 1367 | Only Inkling Small measured |
| LMArena Text: French | Not measured | 1435 | Only Inkling Small measured |
| LMArena Text: Spanish | Not measured | 1422 | Only Inkling Small measured |
| LMArena Text: Russian | Not measured | 1394 | Only Inkling Small measured |
| LMArena Text: Polish | Not measured | 1428 | Only Inkling Small measured |
| LMArena Text: multi-turn | Not measured | 1416 | Only Inkling Small measured |
| LMArena Text: longer queries | Not measured | 1402 | Only Inkling Small measured |
| LMArena Text: writing and language | Not measured | 1357 | Only Inkling Small measured |
| LMArena Text: entertainment and media | Not measured | 1352 | Only Inkling Small measured |
| LMArena Vision: English | Not measured | 1243 | Only Inkling Small measured |
| LMArena Vision: Chinese | Not measured | 1292 | Only Inkling Small measured |
| LMArena Vision: reading text | Not measured | 1243 | Only Inkling Small measured |
| LMArena Vision: humor | Not measured | 1207 | Only Inkling Small measured |
| LMArena Vision: creative writing | Not measured | 1205 | Only Inkling Small measured |
| Neither model has a result on the other 16 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | GPT-5.3-Codex | Inkling Small | Leader |
|---|---|---|---|
| Neither model has a result on 5 boards here | |||
What each workload costs
Three fixed token mixes at each model's listed price, so per-token rates become a bill.
Chat turn
1K input + 500 output tokens
Inkling Small costs less
Repository review
50K input + 3K output tokens
Inkling Small costs less
Agent loop
200K input + 10K output tokens
Inkling Small costs less
Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.
Specification differences
The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.
| Specification | OpenAI GPT-5.3-Codex | Thinking Machines Inkling Small |
|---|---|---|
| Maker | OpenAI | Thinking Machines |
| Weights | No public weights listed | Open weights |
| Released | February 24, 2026 | July 30, 2026 |
| Context window | 400K | 524K |
| Input $/Mtok | $1.75 | $0.45 |
| Output $/Mtok | $14.00 | $1.20 |
| Coding index | 29.5 | 29.9 |
| Independent measurements behind it | 1 | 1 |
| Cost per solved task | $0.59 | $0.16 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is GPT-5.3-Codex better than Inkling Small for coding?
GPT-5.3-Codex and Inkling Small are level for coding, 29.5 against 29.9 on the Vibe Coding Index, so price and context decide. Pick GPT-5.3-Codex when what matters is LiveCodeBench (Vals AI) or Vibe Code Bench (Vals AI), where it leads. Pick Inkling Small when output tokens cost 11.7x less, or when a solved task costs $0.16 against $0.59.
Which is cheaper, GPT-5.3-Codex or Inkling Small?
GPT-5.3-Codex costs $1.75 per million input tokens and $14.00 per million output tokens; Inkling Small costs $0.45 and $1.20. Per solved SWE-bench Verified task, GPT-5.3-Codex costs $0.59 and Inkling Small $0.16.
Which has the bigger context window, GPT-5.3-Codex or Inkling Small?
Inkling Small, with 524K tokens against 400K.
How many benchmarks is the GPT-5.3-Codex vs Inkling Small comparison based on?
13 benchmarks have a result for both models as of October 21, 2026. GPT-5.3-Codex's coding index rests on 1 independent benchmark and Inkling Small's on 1. Where only one model has a result, the page says so instead of naming a winner.