GPT-6 Luna is the fast, cost-efficient tier of OpenAI's GPT-6 model family, sitting below GPT-6 Sol and the larger GPT-6 Astra model that opened the generation. It is a proprietary multimodal transformer that accepts text and image input and returns text, and it exposes an adjustable reasoning effort setting so the same model can run in a low-latency mode or spend additional inference compute on harder problems. OpenAI positions it for high-volume and latency-sensitive workloads such as conversational assistants, classification, and lightweight agentic pipelines, while noting that at higher reasoning effort it handles software engineering and computer-use tasks that previously required a Sol-tier model.
The model supports a context window of roughly 1,050,000 input tokens with a maximum output of 128,000 tokens, which allows long documents, extended agent traces, and large code repositories to be processed in a single request. OpenAI describes the GPT-6 generation as improving factual reliability and adopting a more concise communication style relative to the GPT-5.6 series, and attributes the efficiency of the Sol and Luna tiers to gains in caching and inference rather than to reduced capability. Architecture details, parameter counts, and training data are not published.
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Past 30 DaysVision Evals is Roboflow's ground-truth benchmark: every model runs the same real-world samples across five vision tasks, and answers are scored against ground truth.
Evals updated October 13, 2026Pricing updated October 17, 2026
GPT-6 Luna averages 69.7% across the five Vision Evals tasks, ranking #21 of 63 models overall.
Its weakest relative showing is OCR, ranking #30 of 47 at 59.8%.
At $0.0004 per sample it is the 10th cheapest of the 63 benchmarked models, and its average inference time of 10.2s per sample makes it the 30th fastest.
Field medians: Object Detection 54.4%, Counting 63.5%, Identification 84.4%, OCR 63.6%, Reasoning 57.6%.
| Task | Score | Field (0 to 100) | Rank | Cost / sample | Speed |
|---|---|---|---|---|---|
| Object Detection (low) | 65.5% ±0.4, Mean of 3 runs, range 65.2 to 66.0 | #15 of 63 | $0.0006 | 15.15s | |
| Object Detection (high) | 68.0% ±0.7, Mean of 3 runs, range 67.3 to 68.6 | #14 of 31 | $0.0014 | 21.67s | |
| Counting (low) | 71.6% ±0.0, Mean of 3 runs, range 71.6 to 71.6 | #17 of 63 | $0.0002 | 5.68s | |
| Counting (high) | 72.1% ±0.7, Mean of 3 runs, range 71.6 to 73.0 | #19 of 31 | $0.0004 | 8.02s | |
| Identification (low) | 87.5% ±3.1, Mean of 3 runs, range 84.4 to 90.6 | #26 of 63 | $0.0002 | 4.72s | |
| Identification (high) | 87.5% ±3.1, Mean of 3 runs, range 84.4 to 90.6 | #17 of 31 | $0.0002 | 4.10s | |
| OCR (low) | 59.8% | #30 of 47 | $0.0004 | 9.31s | |
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| OCR (high) | 62.5% | #26 of 47 | $0.0013 | 26.32s | |
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| Reasoning (low) | 64.2% ±3.0, Mean of 3 runs, range 60.3 to 66.2 | #24 of 63 | $0.0003 | 8.96s | |
| Reasoning (high) | 71.1% ±2.3, Mean of 3 runs, range 68.2 to 72.8 | #24 of 50 | $0.0004 | 7.71s | |
Overall benchmark score against estimated cost per sample, on a log scale. Upper-left is the sweet spot: high quality at low cost.
62 models on the current benchmark · scores and efficiency pooled across all five tasks at low effort · GPT-6 Luna highlighted
GPT-6 Luna scores are the mean of 3 runs per task at both low and high effort; OCR is a single preliminary run · Methodology
View all Vision Evals →GPT-6 Luna costs $0.100 per 1M input tokens and $0.500 per 1M output tokens.
Pricing updated Oct 17, 2026
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GPT-6 Luna is proprietary: the weights are not distributed, and the GPT-6 Luna license is the vendor's commercial terms of service that you accept when you call the API.
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Yes. GPT-6 Luna accepts image input and handles OCR, object counting, identification, visual reasoning, and object detection. On Roboflow's Vision Evals its strongest task is Object Detection at 65.5% (#15 of 63 at low effort). You can test it on your own image in the demo above.
Yes. it scores 59.8% (#30 of 47 at low effort) on Vision Evals OCR, which covers single readings, full transcriptions, structured JSON, and locating text with boxes. Within that, full transcriptions score 80%, and returning the fields of a label or form as JSON scores 78.2%.
It's serviceable. On Vision Evals, GPT-6 Luna scores 65.5% mAP@50 on object detection (#15 of 63 at low effort) and 71.6% judge-graded accuracy on object counting.
On our benchmark's task mix, GPT-6 Luna averages $0.0004 per sample at $0.10 per 1M input and $0.50 per 1M output tokens (#10 of 63 on cost), with an average speed of 10.2s per sample across the benchmark. Actual cost depends on your images and prompts.
On the overall Vision Evals ranking, GPT-6 Luna sits #21 of 63 at 69.7%, just behind Claude Opus 5 (70.9%) and just ahead of Claude Haiku 5.5 (69.6%). See the full side-by-side: GPT-6 Luna vs Claude Opus 5.