Model comparison
GPT-5.5 vs NVIDIA Nemotron 3 Ultra
OpenAI against NVIDIA, compared on context, price, and verified benchmark results.
Catalog record checked September 3, 2026Individual provider fields may changeEvidence confidence: High — see receipts below
OpenAI
GPT-5.5
Frontier
NVIDIA
NVIDIA Nemotron 3 Ultra
Frontier · Open weights
| Specification | GPT-5.5 | NVIDIA Nemotron 3 Ultra |
|---|---|---|
| Provider | OpenAI | NVIDIA |
| Tier | Frontier | Frontier |
| Context window | Winner: 1.05M | 1M |
| Max output | 128K | Not verifiedUnverified |
| Input / 1M tokens | $5 | Winner: $0.50 |
| Output / 1M tokens | $30 | Winner: $2.20 |
| Weights | Closed | Open |
| Parameters | Not disclosedUnverified | 550B total / 55B active (MoE) |
| Reasoning levels | none, low, medium, high, xhigh, max | low, high, max |
| Modalities | text, image | text |
| API model id | gpt-5.5 | nemotron-3-ultra-550b-a55b |
| Released | April 23, 2026 | June 4, 2026 |
| Artificial Analysis Intelligence Index [xhigh] (2026-08-14) | 58 | Not verifiedUnverified |
| Artificial Analysis Intelligence Index (2026-08-14) | Not verifiedUnverified | 54 |
| SWE-bench Verified (2026-09-01) | 82.6 | Not verifiedUnverified |
| Terminal-Bench 2.1 (2026-07-27) | 83.4 | Not verifiedUnverified |
| GPQA Diamond (2026-07-27) | 93.5 | Not verifiedUnverified |
| Humanity's Last Exam (2026-04-23) | 52.2 | Not verifiedUnverified |
Prices are USD per million tokens at standard rates, excluding batch and caching discounts. Bold indicates the better figure where one is objectively better. Values we could not confirm from the provider are shown as “Not verified” rather than estimated.
Benchmark receipts
- 2026-09-01: vals.ai SWE-bench Verified leaderboard (independent, mini-swe-agent bash-only); official SWE-bench not publishedReal GitHub issue resolution: does the model's patch pass the hidden tests. Comparability: comparable with caveat — Post-audit vendor claims and pre-audit scores sit on different task trust levels; scaffolding (agent harness, compute budget) also dominates results. Never aggregate across scaffolds.
- 2026-08-14: Artificial AnalysisComposite index blending reasoning, knowledge, and coding evals into one 0–100 score. Comparability: directly comparable — AA occasionally rebaselines the index scale between snapshots — a score captured on one date is only comparable to same-snapshot scores (check measuredAt).
- 2026-07-27: Kimi K3 model card (vendor-reported, xhigh); announcement charts show 93.6 — minor conflict preservedAgentic terminal work: multi-step tasks executed in a sandboxed shell environment. Comparability: comparable with caveat — Scores across Terminal-Bench major versions (v1 vs v2) are NOT comparable; harness configuration (container, time limits) also shifts results.
- 2026-04-23: OpenAI — Introducing GPT-5.5 (vendor, with tools; 41.4 no tools)Frontier-knowledge ceiling: extremely hard multi-domain questions written to be near-impossible without deep expertise. Comparability: comparable with caveat — Subset/tool configurations (text-only vs with-tools) differ between vendors and materially change scores; must match configuration to compare.
Pricing tiers: GPT-5.5: Standard $5/$30 per MTok; >272K input billed 2x in / 1.5x out. Cached input $0.50/MTok; batch $2.50/$15. · NVIDIA Nemotron 3 Ultra: Open weights (weights + data + recipes); $0.50/$2.20 per MTok is the third-party hosted rate (OpenRouter). 550B/55B MoE.
GPT-5.5
GPT-5.5 is OpenAI's previous flagship — strong on Terminal-Bench 2.0 (82.7%) and 1M-token context.
Best for
- Reasoning
- Agentic coding
- Long-context work
Watch out
Superseded by GPT-5.6 Sol on quality; still a capable, widely integrated model.
NVIDIA Nemotron 3 Ultra
Nemotron 3 Ultra is NVIDIA's open-weight (550B/55B) frontier MoE with a 1M-token context.
Best for
- Open-weight frontier
- Self-hosting on NVIDIA GPUs
- Reasoning
Watch out
Top US open-weight until Thinking Machines Inkling; verify hosted pricing.
When the cheaper one wins
NVIDIA Nemotron 3 Ultra is cheaper on output at $2.20 per million tokens against $30 for GPT-5.5 — about 14×. Use the cheaper tier for classification, extraction, summarisation, and any task where the expensive model’s extra score does not change the accepted output. The expensive one only pays if your hardest task actually fails on the cheap tier. These are standard-tier API rates, excluding batch and cache discounts.
Run the model pickerEvidence confidence: High
How strong and complete the evidence behind this comparison is — not a prediction of which model is better.
- Pricing verified on both sides — Input and output rates are verified for both models.
- 3/5 core specs verified on both sides — Not published for at least one side: max output, parameter count.
- 1 shared named benchmark with differing scores — Measured on: Artificial Analysis Intelligence Index.
- Verified within the last 90 days — Newest catalog check was 8 days ago.
- Both models carry source citations — Each side has at least two catalog sources on record.
Source receipts
Each catalog figure was checked against the provider or an independent second source on the date shown.
- GPT-5.5: OpenAI — Introducing GPT-5.5 (accessed 2026-08-29)
- GPT-5.5: OpenAI API pricing (gpt-5.5 $5/$30) (accessed 2026-08-29)
- NVIDIA Nemotron 3 Ultra: NVIDIA — Nemotron (accessed 2026-08-29)
- NVIDIA Nemotron 3 Ultra: NVIDIA Nemotron 3 Ultra (accessed 2026-08-29)
Related comparisons
- Claude Fable 5.1 vs GPT-5.5
- Claude Fable 5.1 vs NVIDIA Nemotron 3 Ultra
- Claude Fable 5 vs GPT-5.5
- Claude Fable 5 vs NVIDIA Nemotron 3 Ultra
- Claude Mythos 5.1 vs GPT-5.5
- Claude Mythos 5.1 vs NVIDIA Nemotron 3 Ultra
Diving deeper on one model? GPT-5.5 · NVIDIA Nemotron 3 Ultra
Common questions
GPT-5.5 vs NVIDIA Nemotron 3 Ultra
Answered from the verified figures on this page rather than general guidance.
Is GPT-5.5 or NVIDIA Nemotron 3 Ultra cheaper for input?
NVIDIA Nemotron 3 Ultra is cheaper at $0.50 per million input tokens, against $5 for GPT-5.5 — roughly 10× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; GPT-5.5 has tiered pricing: Standard $5/$30 per MTok; >272K input billed 2x in / 1.5x out. Cached input $0.50/MTok; batch $2.50/$15. NVIDIA Nemotron 3 Ultra has tiered pricing: Open weights (weights + data + recipes); $0.50/$2.20 per MTok is the third-party hosted rate (OpenRouter). 550B/55B MoE.
Is GPT-5.5 or NVIDIA Nemotron 3 Ultra cheaper for output?
NVIDIA Nemotron 3 Ultra is cheaper at $2.20 per million output tokens, against $30 for GPT-5.5 — roughly 14× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; GPT-5.5 has tiered pricing: Standard $5/$30 per MTok; >272K input billed 2x in / 1.5x out. Cached input $0.50/MTok; batch $2.50/$15. NVIDIA Nemotron 3 Ultra has tiered pricing: Open weights (weights + data + recipes); $0.50/$2.20 per MTok is the third-party hosted rate (OpenRouter). 550B/55B MoE.
Which has the larger context window, GPT-5.5 or NVIDIA Nemotron 3 Ultra?
GPT-5.5 accepts 1.05M tokens against 1M for NVIDIA Nemotron 3 Ultra. This only matters if you routinely send very long documents or large codebases.
Do GPT-5.5 and NVIDIA Nemotron 3 Ultra support the same reasoning levels?
GPT-5.5 exposes none, low, medium, high, xhigh, max, while NVIDIA Nemotron 3 Ultra exposes low, high, max.
Should I use GPT-5.5 or NVIDIA Nemotron 3 Ultra?
Both sit in the frontier tier, so the choice usually comes down to price and context rather than capability. GPT-5.5 suits reasoning; NVIDIA Nemotron 3 Ultra suits open-weight frontier.
Can I self-host GPT-5.5 or NVIDIA Nemotron 3 Ultra?
NVIDIA Nemotron 3 Ultra publishes open weights, but self-hosting and third-party provider access depend on the licence, hardware, serving support, and availability. GPT-5.5 is a closed model whose supported access paths are controlled by its provider.
Next step
Choosing between them
The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.
- Input price: NVIDIA Nemotron 3 Ultra costs $0.50 per 1M tokens versus $5 for GPT-5.5 — a 10x difference at the headline tier.
- Context: GPT-5.5 takes 1.05M against 1M for NVIDIA Nemotron 3 Ultra — only decisive if your prompts approach the smaller window.
- Measured capability: GPT-5.5 leads Artificial Analysis Intelligence Index 58 to 54 (measured 2026-08-14).
- Deployment: NVIDIA Nemotron 3 Ultra publishes weights you can self-host; the other is API-only.
Choosing a harness rather than a model — Cursor, Copilot, Claude Code, Windsurf, or Lovable? Compare agentic harnesses · Latest releases.