GPT-5.6 Luna vs Solar Pro 4: side-by-side summary

GPT-5.6 Luna and Solar Pro 4 are available through the OpenRouter API, so switching between them takes a model slug change rather than a new integration.

GPT-5.6 Luna, from OpenAI, has a 1,050,000-token context window and is priced at $0.20/M tokens input, $1.20/M tokens output on OpenRouter.

Solar Pro 4, from upstage, has a 524,288-token context window and is priced at $0.03/M tokens input, $0.12/M tokens output on OpenRouter.

Context window

• GPT-5.6 Luna: 1,050,000 tokens
• Solar Pro 4: 524,288 tokens

Price

• GPT-5.6 Luna: $0.20/M tokens input, $1.20/M tokens output
• Solar Pro 4: $0.03/M tokens input, $0.12/M tokens output

Provided by

• GPT-5.6 Luna: OpenAI
• Solar Pro 4: upstage

• GPT-5.6 Luna model details, providers and pricing
• Solar Pro 4 model details, providers and pricing