Head-to-head comparison
DeepSeek V4.1 FlashvsGPT-6.1 Sol
DeepSeek V4.1 Flash and GPT-6.1 Sol are the two models that redefined "cheap and capable" in September 2026 from opposite directions. V4.1 Flash is MIT-licensed open weights with native vision at $0.15 per million input tokens off-peak. Sol is OpenAI's closed efficiency model at $2/$10 with near-Astra claims.
At a glance
| DeepSeek V4.1 Flash | GPT-6.1 Sol | |
|---|---|---|
| Category | Chat | Chat |
| Function | Open-weight model | Efficiency model |
| Pricing | Freemium | Paid |
| Starting price | Open weights free; API $0.15 / $0.60 per million tokens off-peak (double at peak), cache hits $0.003 | $2 / $10 per million tokens; cached input $0.10 |
| Released | September 2026 | September 2026 |
DeepSeek V4.1 Flash
Pros
- The most permissive licence in the 500B+ class at release
- Very low API prices even after the September increase
- Vision without a separate model
Cons
- Self-hosting a ~750B model is out of reach for most teams
- Peak-hour pricing is double
- Chinese-hosted API considerations for data
GPT-6.1 Sol
Pros
- Brings GPT-6-class work down to the $2/$10 price tier
- Spares plan usage limits compared with Astra in ChatGPT Work
- Immediately available across OpenAI surfaces
Cons
- Not available in the standard ChatGPT chat picker at launch — Work and Codex only
- "Near-Astra" is OpenAI's claim; independent evaluations pending
- Arrived alongside a cut to the $200 Pro plan's allowance
Which one should you pick?
Pick DeepSeek V4.1 Flash if
Cost per token dominates, you want the option to self-host or use OpenRouter, or you need a permissive licence for a product.
See DeepSeek V4.1 Flash details →Pick GPT-6.1 Sol if
You need OpenAI's ecosystem (Codex, ChatGPT Work, plugins), stronger guarantees on data handling, or the highest quality at the $2/$10 tier.
See GPT-6.1 Sol details →Bottom line
V4.1 Flash is more than ten times cheaper per token and open. Sol is the safer enterprise choice with the stronger vendor claims. Many teams route by task: Flash for volume, Sol for the hard cases.