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GPT-6.1 Sol costs a fifth of GPT-6 Astra and halves the price of cached input

It lists at the same price as Claude Sonnet 5.5, but its cached input now costs half as much.

By Think Facility · September 29, 2026 · OpenAI AI models

OpenAI released GPT-6.1 Sol on September 29, 2026, and priced it at $2 per million input tokens and $10 per million output. That's a fifth of what GPT-6 Astra costs, and OpenAI's own model page sells it as "Near-Astra performance for complex work at a lower cost."

The list price didn't move from GPT-6 Sol. The cache did. Cached input now costs $0.10 per million tokens, half the old Sol's $0.20, and that's the number Altman led with.

Input

$2.00 per 1M tokens

Output

$10.00 per 1M tokens

Cached input

$0.10 per 1M tokens

Context window

1,050,000

Knowledge cutoff

Apr 30, 2026

Where it sits against Astra

OpenAI's page says 6.1 Sol is for complex coding, computer use and professional work, and tells developers to compare it with Astra on their own tasks to judge the tradeoff between quality and cost. That's a fair warning. The docs call it near-Astra and stop there, and the benchmark tables live on openai.com, which wouldn't load for us today.

On paper the two are close. Both take 1,050,000 tokens of context and write up to 128,000 tokens back, and both have an April 30, 2026 knowledge cutoff. Astra is $10 in and $50 out.

Some settings are gone, too. 6.1 Sol drops the none and minimal reasoning levels that GPT-6 Sol offered, so code that ran the old Sol at none has to move to low. Tool calls need the Responses API.

The comparison that changed

Anthropic launched Claude Sonnet 5.5 the day before, at the same $2 and $10. Its cache reads cost $0.20 per million tokens.

So GPT-6 Sol and Sonnet 5.5 matched line for line. Now OpenAI's cached input is half Anthropic's. That matters most to agents and coding tools, which send the same long prompt over and over. Anthropic's counter is tokens: it says Sonnet 5.5 typically needs far fewer of them to do the same work, which is why our Sonnet 5.5 brief led with cost per task.

What Altman said

He posted a minute or two before his dots announcement, and kept it to the price.

You call it as gpt-6.1-sol. OpenAI says it supports US and EU data residency, though fast mode isn't available with the EU option.