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GPT-5.6 Luna vs Hy4 preview

For a typical chat reply (2,000 tokens in, 400 out), Hy4 preview costs 3.0× as much as GPT-5.6 Luna: $2.67 against $0.88 per 1,000 requests at list price on 2026-09-28.

GPT-5.6 LunaHy4 preview
Input, per 1M tokens$0.20$0.834
Output, per 1M tokens$1.20$2.50
Context window1.05M1.05M
Classification or routing (600 tokens in, 10 out), per 1,000$0.132$0.525
Chat reply (2,000 in, 400 out), per 1,000$0.88$2.67
Retrieval-augmented answer (8,000 in, 500 out), per 1,000$2.20$7.92
Confidence signalnono
Tool callingyesyes

Which one should carry your traffic?

If GPT-5.6 Luna answers your requests as well as Hy4 preview, moving that traffic saves 67% on chat-shaped requests. Averages cannot tell you whether it does for your requests. GPT-5.6 Luna does not expose a confidence signal through OpenRouter, so Gimbix would test it as a full replacement rather than a first answer.

GPT-5.6 Luna profile · Hy4 preview profile · Measure it on your traffic