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AI model names in 2026, explained

● Last updated August 25, 2026
Sasha / Models and Research desk

Model naming stopped being descriptive some time in 2025. A number no longer tells you which model is newer, a name no longer tells you which is better, and the same generation now ships in tiers that differ more in price than in capability. This page is a decoder for what is actually on the market as of August 25, 2026, and it will need updating, because everything on it has a shelf life measured in weeks.

OpenAI

The current generation is GPT-5.6, which went public on July 8, 2026 in three named tiers: Sol, Terra and Luna. The version number is shared; the names separate them.

Sol is the tier OpenAI points at the hardest work. It scored 61 on the Artificial Analysis Intelligence Index at maximum effort settings in August 2026, and it is the model behind the headline results, including a hacking benchmark record in July and a mathematics result where a neurosurgery resident used it while proving a conjecture open for 22 years.

Luna became the free ChatGPT default in August 2026, when OpenAI removed rate limits on text chats across every tier.

Two variants sit outside the tier structure. GPT-5.6-Cyber, released August 11, 2026, is security-specialized and answers about 95 percent of the questions the general models refuse. Ultrafast, previewed August 14, is not a model but a serving mode, running Sol at up to 750 tokens per second.

Pricing has moved in both directions and fast. OpenAI cut Luna prices by 80 percent on July 31, then cut Sol API and credit pricing by more than 20 percent on August 24 for a three-month window.

Anthropic

Anthropic’s lineup is the hardest to read, because the expensive model and the best-scoring model are not the same model.

Fable 5 is the top commercial tier at $50 per million output tokens. Opus 5, released July 25, 2026, costs $25 per million output tokens, the same as the older Opus 4.8 and half of Fable 5. On FrontierBench v0.1 it comes within 0.5 percent of Fable 5, and on the Artificial Analysis Intelligence Index at max effort it scores 63 against Fable 5’s 62. Ramp spend data cited in August put Fable 5 at only 11 percent of business spend on Anthropic models, which is what happens when the cheaper model matches the expensive one.

Mythos 5 is the frontier system, referenced in Anthropic’s own safety disclosures rather than sold as a consumer tier. It appears in the company’s August 2026 risk report, and the UK AI Safety Institute attributed 17 of 19 catalogued rogue agent actions to it. The same risk report disclosed an unreleased internal system called Model 2, described as somewhat more capable than Mythos 5 and used heavily inside the company for coding and data generation.

The Opus 4.x line, 4.6 through 4.8, is the prior generation and still in use. In August 2026 a thread on r/ClaudeAI reporting a downgrade from Opus 5 back to Opus 4.6 described the difference as night and day, part of a run of complaints about Opus 5’s verbosity. Sonnet 5 occupies the mid tier.

Google

Google is on the Gemini 3.x line, and its release order has been unusual. Gemini 3.7 Flash shipped on August 16, 2026, three weeks after 3.6, while Gemini 3.5 Pro stayed delayed, meaning the higher version number in the fast tier arrived before the lower version number in the capable tier. Gemini’s scale is the number that matters commercially: Alphabet’s Q2 results put it at 950 million users.

The Chinese labs

This is where the naming is most conventional and the results are least predictable.

Kimi K3, from Moonshot, is a 2.8 trillion parameter mixture-of-experts model that debuted at number one on Arena.ai’s Frontend Code Arena with 1,679 points, ahead of Fable 5 at 1,631 and GPT-5.6 Sol at 1,618. It scores 60 on the Artificial Analysis Intelligence Index. Its weights were published in July 2026, the largest open weight release to that point.

DeepSeek V4, in Pro and Flash variants, went the other way on price, raising API rates up to 12 times with peak-hour billing on August 14 after V4-Flash pushed Terminal Bench 2.1 from 61.8 to 82.7 at unchanged prices two weeks earlier.

Qwen3.8-Max from Alibaba was announced August 3 at 2.4 trillion parameters with open weights promised within a week. GLM-5.3 from Z.ai had its open weights delayed by two weeks on August 23, after the model found 2,436 flaws across 269 open-source projects, 1,097 of them medium to high severity.

How to read a benchmark claim

Three habits make the numbers usable.

Check the effort setting. The Artificial Analysis figures quoted above are at maximum effort, meaning the model is allowed to spend heavily on reasoning before answering. The same model at default settings scores lower and costs far less. A comparison that does not state the setting is not a comparison.

Check the domain. Kimi K3 leads a frontend coding arena and sits fourth on a general intelligence index in the same month. Both are true. Neither generalizes.

Check the date. The spread between the top four models on the aggregate index is four points. Within that margin, the leader changes with each release, and the release cadence in 2026 has been roughly monthly per lab. Any statement about which model is best is a statement about a week.

The more durable observation is about price rather than capability. The gap between the top and second tier inside a single lab, $50 against $25 per million output tokens at Anthropic, is now larger in practical terms than the gap between labs at the same tier. That is why the choice for most work is which tier to buy, not which lab to trust.

Quick answers

What is GPT-5.6 Sol?

Sol is the top tier of OpenAI's GPT-5.6 family, which went public on July 8, 2026 in three named versions: Sol, Terra and Luna. Sol is the model OpenAI points at the hardest tasks, and Luna became the free ChatGPT default in August 2026. A separate security-specialized version, GPT-5.6-Cyber, shipped on August 11, 2026.

What is the difference between Claude Fable 5 and Claude Opus 5?

Fable 5 is Anthropic's expensive top model, priced at $50 per million output tokens. Opus 5, released July 25, 2026, costs $25 per million output tokens, half of Fable 5, and comes within 0.5 percent of it on FrontierBench v0.1 while scoring slightly higher on the Artificial Analysis Intelligence Index at max effort, 63 against 62. Ramp spend data cited in August 2026 put Fable 5 at only 11 percent of business spend on Anthropic models, which is the price gap showing up in behavior.

Which AI model is the best right now?

No single model leads across tasks, and the aggregate scores sit within a few points of each other. At max effort on the Artificial Analysis Intelligence Index in August 2026, Claude Opus 5 scored 63, Claude Fable 5 62, GPT-5.6 Sol 61 and Kimi K3 60. On Arena.ai's Frontend Code Arena, Kimi K3 took first place with 1,679 points ahead of Fable 5 at 1,631 and GPT-5.6 Sol at 1,618. The ranking depends on the benchmark and changes within weeks.

Why did AI labs stop using version numbers?

They did not, they added names on top of them. A version number tracks a training generation, while the name distinguishes tiers within that generation that differ in cost, speed and capability. GPT-5.6 Sol and GPT-5.6 Luna share a generation but are not the same product, and the price gap between tiers is now larger than the capability gap between labs.