OpenAI paper reveals three GPT-5.6 Pro models, breaking with single top-tier strategy

An OpenAI benchmark paper suggests that the Pro tier of GPT-5.6 could ship in three variants. That would be the first major change to ChatGPT Pro's structure since the plan launched.

OpenAI officially unveiled the GPT-5.6 generation in late June, splitting it into three models. Sol handles the hardest tasks, Terra targets high-volume business workloads, and Luna covers faster, cheaper everyday queries. Pro variants weren't part of the announcement.

Now a new OpenAI paper on a genomics benchmark reveals Pro models for the first time. The results table includes rows for "GPT-5.6 Luna Pro," "Terra Pro," and "Sol Pro," each labeled as "Pro (Extended)" runs.

Pro is no longer just one top-tier model

In the benchmark, Sol Pro hits a pass rate of 31.5 percent, making it the strongest of all 60 tested models. It beats the standard Sol at 28.7 percent and the best non-GPT score, Claude Opus 4.8 at 16.0 percent. The pass rate measures how often a model completes the full multi-step analysis without errors and arrives at the correct final answer.

Until now, ChatGPT Pro was simply the single best model available, being one tier above everything else. The paper suggests that's changing. It lists three parallel Pro variants that mirror the standard GPT-5.6 lineup: a fast one, a high-volume one, and a max-performance one.

Comparing each standard tier at its highest reasoning setting ("max") against its Pro variant shows how the gains play out. All values are pass rates on the full 129-task suite:

In this case, the Pro boost shrinks as you move up the ladder. Luna Pro gains a full seven points over its standard version, while Sol Pro picks up less than three. Extra compute lifts weaker tiers more: Terra Pro lands at 28.5 percent, nearly matching standard Sol at 28.7 percent, which means a high-volume Pro variant performs almost as well as the best standard flagship.

A break from how Pro has always worked

This split would be the first major change to the Pro offering since ChatGPT Pro launched. Instead of one expensive top tier, Pro could become its own three-model lineup where users pick between speed, throughput, and maximum reasoning power based on the task at hand.

Whether this tiered structure will actually show up in ChatGPT isn't clear from the paper. The names come only from the benchmark table so far.

One detail stays hidden, too. For the standard GPT models, the paper reports average token usage as a rough proxy for compute cost, about 33,200 tokens for Sol at its highest setting. For the Pro runs, that number is missing. The authors say no comparable token accounting was available, but the more likely explanation is that OpenAI simply doesn't want to share those figures.