Is GPT-5.6 Luna a good deal?
Whether anything in this catalogue beats GPT-5.6 Luna on both quality and price, and what you give up if it does. A computation on the current catalogue, not an opinion.
13 undominated of 136 · Sep 23, 2026
As of Sep 23, 2026, GLM 5.3 Flash scores higher and costs less than GPT-5.6 Luna for Balanced on LMArena, but it is not a drop-in. You would give up: file.
Inspect model evidence Compare differences & requirements
GLM 5.3 Flash scores 42.0 points higher and costs 47% less, but you would give up: file.
LMArena Elo · higher is better
Scale starts at 1040 Elo
1429.9
Effective $/M · Balanced · lower is better
$0.450/M
LMArena Elo · higher is better
Scale starts at 1040 Elo
1471.9
Effective $/M · Balanced · lower is better
$0.237/M
GPT-5.6 Luna takes file, image, text, returns up to 128,000 tokens from a 1,050,000-token context, and is listed by 7 sellers.
Compared against 136 rated, priced models on this lens: nothing dominates it outright, 5 more dominate it but give something up. GPT-5.6 Luna scores 1429.9 at $0.45 per million tokens for this mix.
Higher score, lower price, named losses
Not a drop-in. The loss is why these are not a recommendation.
| Model | LMArena | Effective $/M | You give up |
|---|---|---|---|
| GLM 5.3 Flash | 1471.9 | $0.237/M | file |
| Gemma 4 31B | 1441.7 | $0.153/M | context, max output, file |
| Hy3 | 1440.6 | $0.144/M | context, file, image |
| Gemma 4 26B A4B | 1434.5 | $0.143/M | context, file |
| DeepSeek V4 Flash 0423 | 1431.8 | $0.103/M | context, file, image |
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Constraint: replacements must preserve the model’s capabilities; any losses remain named trade-offs.
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