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OpenAI · model passport

OpenAI: GPT-5.3-Codex

gpt-5-3-codex
  • Cloud only
  • Proprietary licence
  • 400,000 context
  • Released 2026-10-09(first seen on LMArena)
5/27axes covered
Best percentile
90.7IFBench (Artificial Analysis)
Cohort standing
64.4median 60.5

What the data says

Benchmarked on 5 of 27 tracked axes. Every figure below is the model's own published result on that board.

Strongest axes

  • 90.7 pct — IFBench (Artificial Analysis) (75.4%)
  • 88.6 pct — Terminal-Bench (78.4%)
  • 88 pct — LiveBench (72.8%)

Uneven: 49 percentile points between its best and worst axis — 90.7 pct on IFBench (Artificial Analysis) versus 41.7 pct on WebDev Arena.

  • IFBench (Artificial Analysis)90.7 pct75.4%Verify →
  • Terminal-Bench88.6 pct78.4%Verify →
  • LiveBench88 pct72.8%Verify →
  • SWE-bench Verified56.3 pct74.8%Verify →
  • WebDev Arena41.7 pct1,407Verify →
  • OverallNot benchmarked
  • Vision ArenaNot benchmarked
  • Factuality ArenaNot benchmarked
  • Search ArenaNot benchmarked
  • Document ArenaNot benchmarked
  • Agent ArenaNot benchmarked
  • GPQA DiamondNot benchmarked
  • AIME (math)Not benchmarked
  • FrontierMathNot benchmarked
  • SimpleQA VerifiedNot benchmarked
  • ARC-AGI-2Not benchmarked
  • Humanity's Last ExamNot benchmarked
  • SimpleBenchNot benchmarked
  • BFCL v4 (function calling)Not benchmarked
  • SWE-bench Verified (live board)Not benchmarked
  • Terminal-Bench 4.0Not benchmarked
  • MMLU-Pro (Artificial Analysis)Not benchmarked
  • LiveCodeBench (Artificial Analysis)Not benchmarked
  • HHEM Hallucination (Vectara)Not benchmarked
  • CodingNot benchmarked
  • Instruction followingNot benchmarked
  • Hard promptsNot benchmarked

Percentiles are the model's standing within each board's own population. Axes marked "not benchmarked" have no published result for this model — that is an absence of data, not a low score.

How to run it

Use it hosted

API model IDopenai/gpt-5.3-codex
Context length400,000 tokens
Max output128,000 tokens
Acceptstext, image, file
Input price$1.75 per 1M tokens
Cached input price$0.17 per 1M tokens
Output price$14 per 1M tokens

API parameters this endpoint supports

Include reasoningMax completion tokensMax tokensReasoningReasoning effortResponse formatSeedStructured outputsTool choiceTool callingVerbosity

Example request

curl https://openrouter.ai/api/v1/chat/completions \
  -H "Authorization: Bearer $OPENROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"openai/gpt-5.3-codex","messages":[{"role":"user","content":"Hello"}]}'

View on OpenRouter →

Identifiers, limits and prices are synced from the upstream source shown above. Any field we haven't synced is left out entirely rather than guessed.

  • GPT-5.3-Codex (Codex Harness) stands at 64.4 (raw mean 73.1) — measured on 5 of 27 axes.

    standingtemplateVerify →

  • GPT-5.3-Codex (Codex Harness) stands at 64.4 versus a cohort median of 60.5 across 172 models released within 180 days — above the peer median.

    cohorttemplateVerify →

Every claim is a computed fact from the current board data, phrased by a low-temperature model call and rejected by a validation gate if any number is not in the source row. How the leaderboards work →