GPT-6 Astra vs GPT-6.1 Sol: API cost and the reasoning tradeoff
Sol is the lower-cost option for the same token workload. Pay Astra's premium where task evaluations show enough benefit to cover the extra input, output, and cache costs.
Astra's base token rates are five times Sol's. Cached input has a tenfold price gap.
GPT-6 Astra's base input and output prices are five times GPT-6.1 Sol's. Cached input has an even wider tenfold rate difference. Both models offer a 1,050,000-token context window, so capacity alone doesn't explain paying more for Astra. This comparison focuses on the cost of the same billed workload and the measurements that can justify routing some tasks to the more expensive model.
By TechCompare · Updated
Cost Comparison
Based on 100,000 input tokens (50% cached), 5,000 output tokens, and 100 requests.Prices are fetched live from OpenRouter and may include temporary promotional discounts not accounted for in our article and comparison figures.
Side-by-side specs
| Spec | GPT-6 Astra | GPT-6.1 Sol |
|---|---|---|
| Standard input per 1M tokens | $10.00 up to 272K input | $2.00 up to 272K input (better on this spec) |
| Standard output per 1M tokens | $50.00 up to 272K input | $10.00 up to 272K input (better on this spec) |
| Cache reads per 1M tokens | $1.00 up to 272K input | $0.10 up to 272K input (better on this spec) |
| Base cache writes per 1M tokens | $12.50 | $2.50 (better on this spec) |
| 100K input + 5K output, no cache hits | $1.25 | $0.25 (better on this spec) |
| 100K input + 5K output, 50% cached input | $0.80 | $0.155 (better on this spec) |
| 300K input + 5K output, no cache hits | $6.375 | $1.275 (better on this spec) |
| Context window | 1,050,000 tokens | 1,050,000 tokens |
| Provider Batch API discount | 50% | 50% |
How they differ
Astra charges $10 input, $50 output, and $1 cache reads per million tokens at base rates. Sol charges $2, $10, and $0.10. A request with 100,000 input and 5,000 output tokens costs $1.25 on Astra or $0.25 on Sol without cache hits. With half the input read from cache, it costs $0.80 or $0.155, a ratio of about 5.16 rather than exactly five. Both apply higher rates to the full request above 272,000 input tokens: double input and cache prices and 1.5 times output prices. At 300,000 input and 5,000 output tokens without cache hits, the totals are $6.375 and $1.275. Both have a 50% provider Batch API discount. These examples omit cache-write charges and tools, while the embedded calculator follows live OpenRouter provider rates.
Verdict
Test Sol first on the workload you plan to deploy, then compare Astra on cases where Sol's results need another attempt or more review. At the base rates, 10,000 uncached example calls cost $2,500 on Sol and $12,500 on Astra. That $10,000 difference is a concrete budget to weigh against saved review time and better outcomes. Using Astra selectively can preserve the benefit on difficult tasks without applying the premium to every request.
Which should you pick?
Choose GPT-6 Astra
Use Astra when it earns its higher price in your evaluations on demanding reasoning, coding, or professional work. Compare cost per accepted result, not just success on a single demonstration. Control prompt growth and reasoning output because both contribute to the premium, and include follow-up calls when estimating the cost of an agent session.
Choose GPT-6.1 Sol
Use Sol when it meets the task's accuracy and completion requirements at an acceptable response time. It has the same advertised context capacity with lower token rates and a lower cache-read price. Keep Astra available for selected failures or difficult cases, and measure whether that routing policy reduces total spending compared with sending every task to Astra.