Parametric CAD Bench
Agents author editable parametric FreeCAD part designs, graded against held-back references for geometry and spec consistency.
Not the same as anniedoris/CADBench. A submission-portal repo exists at github.com/gNucleus-AI/cad-bench-submission. The board shows version 3. Lab results from before it keep their citations without a plotted score.
- Made by
- gNucleus AI
- Released
- 2026
- Kind
- CAD models
- Level
- Expert
- Scored
- Checked automatically
- Answers
- Agent task
- Tasks
- Kept private
- Strongest model tested
- GPT-6 Astra #3 on the capability index
- Last in a launch post
- August 2026
- Last model added
- September 2026
- Scores refreshed
- November 12th, 2026
Claude Opus 5.5 leads with 61% among models released by September 2026
Best score per model from the benchmark's own leaderboard, read on November 12th, 2026. Where a model ran with several settings or harnesses, we keep its best. Every run is in the next chart.
The newest model with a score here came out in September 2026, and nobody has tested a newer one. Among the 20 highest-ranked models on the capability index, these have no score yet:
- Claude Fable 5.2
-
Gemini 4 Carbon - GPT-6.1 Sol
- GPT-6.1 Terra
- and 10 more
- 1 Claude Opus 5.5 max 61%
- 2 GPT-6 Astra max 56.9%
- 3 Claude Fable 5.1 max 56.8%
- 4 Claude Opus 5 max 50.9%
- 5 Gemini 3.8 Flash high 36.2%
- 6 Grok 4.7 high 34.8%
- 7 GPT-5.6 Sol max 30%
- 8 Grok 4.6 high 27.7%
- 9 Kimi K3 max 24.9%
- 10
Muse Spark 1.3 max 20.9% - 11 GPT-5.6 Terra max 17.2%
Source: Official Parametric CAD Bench leaderboard
| # | Model | Score | Setting | Date | Source |
|---|---|---|---|---|---|
| 1 | Claude Opus 5.5 | 61% | max, Claude Code | Sep 2026 | Official leaderboard |
| 2 | GPT-6 Astra | 56.9% | max, Codex | Sep 2026 | Official leaderboard |
| 3 | Claude Fable 5.1 | 56.8% | max, Claude Code | Sep 2026 | Official leaderboard |
| 4 | Claude Opus 5 | 50.9% | max, Claude Code | Jul 2026 | Official leaderboard |
| 5 | Gemini 3.8 Flash | 36.2% | high, mini-swe-agent | Sep 2026 | Official leaderboard |
| 6 | Grok 4.7 | 34.8% | high, Grok Build | Sep 2026 | Official leaderboard |
| 7 | GPT-5.6 Sol | 30% | max, Codex | Jul 2026 | Official leaderboard |
| 8 | Grok 4.6 | 27.7% | high, Grok Build | Aug 2026 | Official leaderboard |
| 9 | Kimi K3 | 24.9% | max, mini-swe-agent | Jul 2026 | Official leaderboard |
| 10 | Muse Spark 1.3 | 20.9% | max, mini-swe-agent | Sep 2026 | Official leaderboard |
| 11 | GPT-5.6 Terra | 17.2% | max, Codex | Jul 2026 | Official leaderboard |
The best score, 61%, costs $574 for the full run
Runs on the cost frontier score higher than any run that's cheaper. The costs are the leaderboard's own estimates, so compare them only within this benchmark.
Source: Official Parametric CAD Bench leaderboard
| Model | Effort | Harness | Score | Cost of the full run | Output tokens |
|---|---|---|---|---|---|
| Claude Opus 5.5 | max | Claude Code | 61% | $574 | |
| Claude Opus 5.5 | max | mini-swe-agent | 58% | $498 | |
| GPT-6 Astra | max | Codex | 56.9% | $318 | |
| Claude Fable 5.1 | max | Claude Code | 56.8% | $1,056 | |
| Claude Opus 5 | max | Claude Code | 50.9% | $1,012 | |
| Gemini 3.8 Flash | high | mini-swe-agent | 36.2% | $272 | |
| Grok 4.7 | high | Grok Build | 34.8% | $670 | |
| GPT-5.6 Sol | max | Codex | 30% | $292 | |
| Grok 4.6 | high | Grok Build | 27.7% | $391 | |
| Gemini 3.8 Flash | high | Antigravity | 27.6% | $197 | |
| Kimi K3 | max | mini-swe-agent | 24.9% | $315 | |
| Muse Spark 1.3 | max | mini-swe-agent | 20.9% | $357 | |
| GPT-5.6 Terra | max | Codex | 17.2% | $215 |
5 models have held number one on the official leaderboard since its release in January 2026
Lab claims count from the day the card came out, independent runs from the model’s release.
Source: Official Parametric CAD Bench leaderboard
Scores over time
All the scores we have, one dot each, so a model tested at several settings appears more than once.
Source: Official Parametric CAD Bench leaderboard
One lab put it in a launch post in the last six months
Launch posts from every lab that has listed it, one tick per post. Tall colored ticks include it, and short gray ones leave it out.
| Date | Launch post | Score | As the post writes it |
|---|---|---|---|
| Aug 3, 2026 |  Qwen 3.8 Max | Parametric CAD Bench |
2 system cards report it, from 1 lab
Besides launch posts, we read the system cards, model cards and technical reports labs publish with a release. They report far more, including safety and frontier-risk tests.
More in Engineering and CAD
- EEBench In use 13 electrical-engineering circuit and PCB design tasks graded by deterministic build checks, simulation and BOM constraints. No LLM judge. Gemini 4 Carbon 83.9%
- 3DCodeBench In use Agentic procedural 3D modeling via code: author engine-ready 3D assets through software APIs. Graded for executability and shape fidelity.
LongCat-2.5 55.4% - CADGenBench Only in system cards Agents construct CAD models from design prompts. The generation split is graded for executability and geometric correctness. Claude Fable 5 45.1%
- PartBench Only in system cards Parametric mechanical part design and CAD-style generation, graded for geometric and manufacturing fidelity. Grok 4.6 58.5%
- LMBuild Not in model cards Language model agents design 3D structures as parts, joints, materials and assembly steps. Scoring checks that the structures can be built and work as intended. GPT-6 Astra 66.5%
- Physical-Engineering's Last Exam Not in model cards Agents produce billable engineering deliverables such as calculation packages, drawings and design reviews in 85 tasks across electrical, civil, structural and mechanical engineering. Automatic graders check constraints, safety limits and the design objective. Claude Opus 5.5 0.49