GPT-6.1 Sol vs GPT-6 Luna: Pick by Judgment or Volume
OpenAI's model lineup changed twice in September 2026, and the result confuses even regular users. Here's the simple version: pick Sol when judgment matters, pick Luna when volume matters. The short answer GPT-6.1 Sol is the near-flagship workhorse: complex coding, multi-step agents, documents, com
Posted on Oct 16 • Originally published at neuraitool.com
OpenAI's model lineup changed twice in September 2026, and the result confuses even regular users. Here's the simple version: pick Sol when judgment matters, pick Luna when volume matters.
GPT-6.1 Sol is the near-flagship workhorse: complex coding, multi-step agents, documents, computer use, research — at one-fifth of Astra's API price.
GPT-6 Luna is the efficiency model: classification, extraction, routing, summaries, bulk transforms — at one-twentieth of Sol's price.
Both share a 1.05M-token context window and 128K max output. The difference isn't how much they can read — it's how much judgment each brings.
Per million tokens: Sol $2.00 in / $10.00 out (cached $0.10); Luna $0.10 in / $0.50 out (cached $0.01); Astra $10.00 in / $50.00 out.
An illustrative 10,000-task workload (2,000 input + 500 output tokens each) costs about $4.50 on Luna, $90 on Sol, $450 on Astra. Model choice is a routing decision, not a preference.
Artificial Analysis scores Sol at 52 on its Intelligence Index (Astra 53, original Sol 48), Luna at 37. Sol matches Astra on DeepSWE coding tasks at roughly a fifth of the cost. But benchmarks are measured at maximum reasoning effort — run both on your own evaluation set and compare cost per accepted result.
Solo devs: Sol for coding and agents, Luna for bulk chores. Product teams: Luna for high-volume low-risk pipeline steps, Sol as the escalation tier. Anyone on GPT-6 Sol today: migrate to 6.1 — same input/output price, cheaper cached input, better benchmarks.
Not a fight for one winner — a routing question. Luna for the bulk, Sol for the hard tail, Astra only when its final capability edge changes the outcome.
Read the full breakdown — timeline, pricing tables, capability details, access by surface — on NeurAITool: Full article: GPT-6.1 Sol vs GPT-6 Luna