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GPT-5.3-Codex vs Nemotron 3 Ultra

Detailed technical comparison between GPT-5.3-Codex (OpenAI) and Nemotron 3 Ultra (Nvidia). 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-5.3-Codex: 5 WinsvsNemotron 3 Ultra: 0 Wins
Context Leader

Nemotron 3 Ultra

512,288 tokens
Agentic Tool-Calling

Tie

Equal Capability
Lowest Latency (TTFT)

Tie

Equal Speed
Input Price Leader

Nemotron 3 Ultra

$0.60 / MTok
OpenAIactive

GPT-5.3-Codex

GPT-5.3-Codex is OpenAI’s most advanced agentic coding model, combining the frontier software engineering performance of GPT-5.2-Codex with the broader reasoning and professional knowledge capabilities of GPT-5.2. It achieves state-of-the-art results...

View GPT-5.3-Codex Full Specs →
Nvidiaactive

Nemotron 3 Ultra

NVIDIA Nemotron 3 Ultra is an open frontier-reasoning and orchestration model from NVIDIA, with 55B active parameters out of 550B total (MoE). Built on a hybrid Transformer-Mamba mixture-of-experts architecture, it...

View Nemotron 3 Ultra Full Specs →

Technical Specifications

🏆 = Superior Spec
SpecificationGPT-5.3-CodexNemotron 3 Ultra
ProviderOpenAINvidia
Context Window400,000 tokens512,288 tokens🏆
Agent SuitabilityN/AN/A
Time to First Token (TTFT)N/AN/A
Deployment Modelmanaged apimanaged api
Production Stabilitystablebeta
API AvailableYesYes
Released Date2026-02-242026-06-04

API Pricing Comparison

Input Price per Million Tokens

GPT-5.3-Codex

$1.75

Nemotron 3 Ultra

$0.60

Output Price per Million Tokens

GPT-5.3-Codex

$14.00

Nemotron 3 Ultra

$3.60

💡 Cost Ratio: Nemotron 3 Ultra is 2.9x cheaper per input token than GPT-5.3-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
93.2%vs87.8%+5.4% GPT-5.3-Codex
GPT-5.3-Codex 🏆
Nemotron 3 Ultra
HumanEvalPython coding & logic synthesis
99.0%vs87.0%+12.0% GPT-5.3-Codex
GPT-5.3-Codex 🏆
Nemotron 3 Ultra
MATHComplex mathematical problem solving
81.6%vs68.2%+13.4% GPT-5.3-Codex
GPT-5.3-Codex 🏆
Nemotron 3 Ultra
GPQAGraduate-level expert reasoning
56.6%vs49.6%+7.0% GPT-5.3-Codex
GPT-5.3-Codex 🏆
Nemotron 3 Ultra
HellaSwagCommonsense reasoning and inference
88.8%vs85.4%+3.4% GPT-5.3-Codex
GPT-5.3-Codex 🏆
Nemotron 3 Ultra
MT-BenchMulti-turn conversation flow quality
9.1%vs9.1%+0.0% Nemotron 3 Ultra
GPT-5.3-Codex
Nemotron 3 Ultra

GPT-5.3-Codex Quirks & Gotchas

No developer gotchas reported.

Nemotron 3 Ultra Quirks & Gotchas

No developer gotchas reported.

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