OpenAI has updated the price-performance positioning of its GPT-5.6 model family, cutting prices for the Terra and Luna tiers while keeping flagship Sol pricing unchanged. For API teams, the distinction matters: lower-cost model options can reduce routine inference spend, but organizations using Sol should not budget for a broad temporary reduction in its standard token rates.
According to OpenAI's GPT-5.6 price-performance update, Luna pricing was reduced by 80% and Terra pricing by 20%. The update also adds a Fast mode for Sol that can provide up to 2.5 times faster speeds at twice the price. It is a throughput option, not a standard-price discount for Sol.
At launch, OpenAI listed GPT-5.6 Sol at $5 per million input tokens and $30 per million output tokens. Terra was listed at $2.50 for input and $15 for output, while Luna was listed at $1 for input and $6 for output. The later update changes the economic case for Terra and Luna, but does not change Sol's stated standard pricing.
What changed in the GPT-5.6 model lineup
The update reinforces a tiered approach to model selection. Sol remains the flagship tier. Terra is the lower-cost option, and Luna is positioned as the fastest and most affordable tier. Rather than lowering every model's price, OpenAI has made the lower-priced tiers more economical and introduced an explicit premium path for faster Sol execution.
