GPT-6.1 Sol vs Claude Sonnet 5.5: equal base prices, different cache costs
Base token prices tie. Sol saves a little on cache reads below its long-prompt boundary, while Sonnet avoids that boundary's surcharge within its context window.
Both charge $2 input and $10 output per million tokens. Cache reuse and prompt length separate them.
GPT-6.1 Sol and Claude Sonnet 5.5 both charge $2 per million input tokens and $10 per million output tokens at standard base rates. An uncached request with the same billed token counts therefore starts at the same price. Their bills diverge when you reuse cached context or send large prompts. Those differences are more useful than declaring a general winner based on a price table that ties on its first two rows.
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-6.1 Sol | Claude Sonnet 5.5 |
|---|---|---|
| Standard input per 1M tokens | $2.00 up to 272K input | $2.00 |
| Standard output per 1M tokens | $10.00 up to 272K input | $10.00 |
| Cache reads per 1M tokens | $0.10 up to 272K input (better on this spec) | $0.20 |
| 100K input + 5K output, no cache hits | $0.25 | $0.25 |
| 100K input + 5K output, 50% cached input | $0.155 (better on this spec) | $0.16 |
| 300K input + 5K output, no cache hits | $1.275 | $0.65 (better on this spec) |
| Input / output above 272K input, per 1M | $4.00 / $15.00 | $2.00 / $10.00 |
| Context window | 1,050,000 tokens | 1,000,000 tokens |
| Provider Batch API discount | 50% | 50% |
How they differ
Sol's cache-read rate is $0.10 per million tokens, compared with Sonnet's $0.20. At 100,000 input and 5,000 output tokens, both cost $0.25 without cache hits. Reading half the input from cache changes that to $0.155 on Sol and $0.16 on Sonnet. Over 10,000 such calls, the $0.005 gap saves $50 on Sol. Prompt length can have a much larger effect. Above 272,000 input tokens, Sol bills the whole request at $4 input, $0.20 cached input, and $15 output per million tokens. Sonnet keeps $2 input, $0.20 cached input, and $10 output within its 1M context window. A 300,000-input, 5,000-output request without cache hits therefore costs $1.275 on Sol and $0.65 on Sonnet. Cache writes and tools are outside these examples, and the embedded chart follows live OpenRouter provider rates.
Verdict
For ordinary prompts, choose using task completion, response time, and integration requirements because the base bill ties. Sol's cache advantage is real, but modest in the 50% reuse example. Sonnet's flat long-context pricing has a larger effect on uncached document workloads. Measure the prompt lengths your application actually sends and the output it actually receives, including reasoning, before translating either pricing pattern into a monthly budget.
Which should you pick?
Choose GPT-6.1 Sol
Use Sol when your OpenAI workflow meets its quality targets and repeated prompt prefixes create consistent cache hits. Keep prompts within the base tier when practical. Compare the savings with the cost of changing providers because a small token discount alone may not justify migrating a stable application, its tooling, and its evaluation coverage.
Choose Claude Sonnet 5.5
Use Sonnet when long prompts regularly exceed Sol's pricing boundary or your existing Claude workflow performs well in your evaluations. Its base rates stay the same within the advertised context window. For smaller prompts, test output length and the number of tool turns rather than assuming the shared headline prices produce identical bills in production.