GPT-6.1 Sol vs Astra: Which Should You Actually Use?

GPT-6.1 Sol vs Astra comes down to price against polish. In my head-to-head app build, Sol finished a working product for $43 while Astra spent $203, and the time was almost identical. Here is where each model wins and how I would combine them.

TL;DR

• Sol costs $2 per million input tokens and $10 output. Astra costs $10 and $50, so Sol is five times cheaper.
• The same build took 42 minutes on Astra and 40 on Sol, using 69 million and 66 million tokens.
• Total spend was $203 for Astra and $43 for Sol.
• Planning with Astra and executing with Sol gave me the best app, with eight phases and the fewest fixes.

GPT-6.1 Sol vs Astra on One Real Build

I had both models build a Whisper Flow style voice app that calls tools like Gmail and Firecrawl for deep research. Same prompt, same stack, and a stretch goal that they use computer use to enable accessibility settings themselves.

I ended up with three apps. Relay Voice used Astra as the lead and Sol as the executor. The other two were zero-to-final builds by each model alone.

How Much Cheaper Is Sol Than Astra?

Sol is about five times cheaper on input and output, and ten times cheaper on cached input. That gap decides which model you hand the long, token-hungry work.

OpenAI says the two are near parity on benchmarks. The biggest lags are computer use and professional documents, so Astra stays the planner and Sol is the executor.

Which Model Built the Better App?

Astra built the more polished app, and Sol built a working one for a fifth of the price. Time was not the gap, with 42 minutes for Astra on high and 40 for Sol.

The Sol app was not as beautiful. I could not drag it, and some settings buttons did not behave. But one Astra prompt could beautify it later, so you spend most of your tokens on the Sol build. Since both models are on different effort levels in practice, I kept Astra on high for the plan.

Where Did Each Model Struggle?

Each one failed somewhere different, which is the case for a hybrid setup. Astra struggled with the research workflow, and many of the citations it brought back were broken. Sol's research worked out of the box.

Sol got most main features down but fumbled the basics, like taking voice as input. I needed five to six more prompts to fix it, while Astra worked on the first try. So bring Astra in as the plumber to clean up what Sol leaves behind.

Should You Plan With Astra and Build With Sol?

Yes, if you are on the $20 or $100 plans, this is what I would do. Give Astra time to plan, then spin up every thread with Sol.

That run created eight phases, the most of any attempt, and needed the fewest tweaks. I told each model it was the lead chat and could spawn its own local threads, pick phase counts, and use computer use. The self-organized threads each had a leader checking on the others. If you run Codex on a budget, this split keeps the meter low.

I also tested these models on my own jobs with a personal AI benchmark, because public numbers rarely match client work. Read the OpenAI pricing page before you commit to a plan.

Final Notes from Mark

Last time I tried Sol it was not even in the conversation next to Opus or Sonnet. This version is far more capable and efficient. I will keep testing it on client work and report back if it beats Opus on anything real.

GPT-6.1 Sol vs Astra FAQs

Is GPT-6.1 Sol cheaper than GPT-6 Astra?

Yes, about five times cheaper on input and output. Astra costs $10 per million input tokens and $50 output. Sol costs $2 input and $10 output. Cached input is $1 on Astra and 10 cents on Sol, which is ten times less.

Is GPT-6.1 Sol as smart as Astra?

OpenAI says it is almost as smart, with near benchmark parity. The biggest gaps are computer use and professional documents. In my build test it needed five to six extra prompts to fix voice input, which Astra got right on the first try.

Should I plan with Astra and build with Sol?

That was my best result. I planned with Astra, then let Sol execute eight phases across separate threads. It worked out of the box with the fewest tweaks. It is a strong option if you are on the $20 or $100 plans and need your tokens to last.

How long did Sol and Astra take to build the same app?

Almost the same. Astra on high took 42 minutes and Sol took 40 minutes, with 69 million and 66 million tokens. Time was not the differentiator. Cost was, at $203 for Astra and $43 for Sol.

Where did GPT-6.1 Sol struggle?

Sol got most features down but struggled with fundamentals like taking voice as input, which needed five to six more prompts. Astra struggled with research. Its citations were often broken, while Sol's worked out of the box.