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gpt-oss-120b vs GPT-5.2-Codex

Detailed technical comparison between gpt-oss-120b (OpenAI) and GPT-5.2-Codex (OpenAI). Review live API token pricing, context window capabilities, time-to-first-token latency, and verified benchmark scores side-by-side.

⚡ Executive Summary & Verdict

Comparison Snapshot

gpt-oss-120b: 0 WinsvsGPT-5.2-Codex: 6 Wins
Context Leader

GPT-5.2-Codex

400,000 tokens
Agentic Tool-Calling

Tie

Equal Capability
Lowest Latency (TTFT)

Tie

Equal Speed
Input Price Leader

gpt-oss-120b

$0.04 / MTok
OpenAIactive

gpt-oss-120b

gpt-oss-120b is an open-weight, 117B-parameter Mixture-of-Experts (MoE) language model from OpenAI designed for high-reasoning, agentic, and general-purpose production use cases. It activates 5.1B parameters per forward pass and is optimized...

View gpt-oss-120b Full Specs →
OpenAIactive

GPT-5.2-Codex

GPT-5.2-Codex is an upgraded version of GPT-5.1-Codex optimized for software engineering and coding workflows. It is designed for both interactive development sessions and long, independent execution of complex engineering tasks....

View GPT-5.2-Codex Full Specs →

Technical Specifications

🏆 = Superior Spec
Specificationgpt-oss-120bGPT-5.2-Codex
ProviderOpenAIOpenAI
Context Window131,072 tokens400,000 tokens🏆
Agent SuitabilityNot yet benchmarkedNot yet benchmarked
Time to First Token (TTFT)No public TTFT dataNo public TTFT data
Deployment Modelmanaged apimanaged api
Production StabilityStable GA (est.)Stable GA (est.)
API AvailableYesYes
Released Date2025-08-052026-01-14

API Pricing Comparison

Input Price per Million Tokens

gpt-oss-120b

$0.04

GPT-5.2-Codex

$1.75

Output Price per Million Tokens

gpt-oss-120b

$0.17

GPT-5.2-Codex

$14.00

💡 Cost Ratio: gpt-oss-120b is 47.3x cheaper per input token than GPT-5.2-Codex.

Want to test both models live?

Run side-by-side prompt benchmarks in our dynamic multi-model Sandbox. Compare execution speeds, latency metrics, and compute actual costs in real-time.

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Benchmark Performance Metrics

Standardized Scores (0–100%)

Scores show verified raw accuracy percentages across standardized AI evaluation suites. Higher bars indicate superior performance in that domain.

MMLUGeneral knowledge & multi-task understanding
79.4%vs93.0%+13.6% GPT-5.2-Codex
gpt-oss-120b
GPT-5.2-Codex 🏆
HumanEvalPython coding & logic synthesis
77.6%vs99.0%+21.4% GPT-5.2-Codex
gpt-oss-120b
GPT-5.2-Codex 🏆
MATHComplex mathematical problem solving
54.8%vs81.4%+26.6% GPT-5.2-Codex
gpt-oss-120b
GPT-5.2-Codex 🏆
GPQAGraduate-level expert reasoning
40.2%vs56.4%+16.2% GPT-5.2-Codex
gpt-oss-120b
GPT-5.2-Codex 🏆
HellaSwagCommonsense reasoning and inference
82.4%vs88.6%+6.2% GPT-5.2-Codex
gpt-oss-120b
GPT-5.2-Codex 🏆
MT-BenchMulti-turn conversation flow quality
8.5%vs9.5%+1.0% GPT-5.2-Codex
gpt-oss-120b
GPT-5.2-Codex 🏆

gpt-oss-120b Quirks & Gotchas

No developer gotchas reported.

GPT-5.2-Codex Quirks & Gotchas

No developer gotchas reported.

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