GPT-6 Sol lists at $2.00/1M / $10.00/1M per 1M tokens. Claude Opus 5.5 lists at $4.00/1M / $20.00/1M. Sol is half on stickers. Cache reads tie at $0.20 per 1M. Same cache read does not mean the same bill once output, writes, and token burn diverge. Rates in TokenCalculator checked 23 Sep 2026.
Compare on one prompt
Open the tools compare page or cost calculator, paste one golden prompt, and hold output size fixed. Do not compare list prices alone. Claude stays Approx in-browser.
Sticker rates: Sol is cheaper
| Meter | GPT-6 Sol | Claude Opus 5.5 |
|---|---|---|
| Input / 1M | $2.00/1M | $4.00/1M |
| Output / 1M | $10.00/1M | $20.00/1M |
| Cache read / 1M | $0.200/1M | $0.200/1M |
| Cache write / 1M (5m) | $2.50/1M | $5.00/1M |
| Batch input / output | $1.00/1M / $5.00/1M | $2.00/1M / $10.00/1M |
| Long-context rule | >272K reprices whole request | Standard rates across 1M window |
| Context window | about 1.05M | 1M |
| Tokenizer in TokenCalculator | Exact (o200k) | Approx (confirm with count_tokens) |
Where the invoice diverges
1. Stickers vs cache
Sol is half on input and output. Cache reads match at $0.20. On short uncached prompts, Sol usually wins the meter. On cache-heavy agents, the gap shrinks toward the fresh input and output lines, and Sol still tends to win unless Opus burns fewer tokens per finished task.
2. Long-context cliff
Sol doubles input and cache rates and multiplies output by 1.5x once input exceeds 272K, for the entire request. Opus 5.5’s published card keeps standard rates across its 1M window. Fat RAG prompts past ~272K favor Opus on the rate card even when Sol wins below the cliff.
3. Cost per finished task
Independent harnesses sometimes show one model finishing agent suites with fewer reasoning tokens even when list rates favor the other. Rate cards rank price. Workloads rank how much thinking each model burns. Re-run your own golden tasks before you generalize from a leaderboard.
Workload cheatsheet
- Short, fresh prompts: lean Sol on the meter unless Claude quality wins evals.
- Cache-heavy agents under 272K: Sol still often cheaper; measure if Opus finishes with fewer steps.
- Prompts past ~272K input: model Sol long-context carefully; Opus keeps flat list rates.
- Batchable offline jobs: both offer ~50% batch when latency allows.
Worked numbers (planning only)
Example A, uncached: 5K input + 1K output. Sol about $0.02. Opus 5.5 about $0.04.
Example B, cache heavy: 100K cached + 5K fresh + 2K output. Sol about $0.02 cache + $0.01 fresh + $0.02 output = $0.05. Opus about $0.02 cache + $0.02 fresh + $0.04 output = $0.08.
Common mistakes
- Declaring Opus cheaper because cache reads match Sol
- Ignoring reasoning token spend when comparing rate cards
- Budgeting Claude with OpenAI Exact token counts
- Forgetting Sol Fast mode is about 2x and can erase the sticker gap
- Assuming ChatGPT Work credits equal Sol API $/1M
Frequently asked questions
Is GPT-6 Sol cheaper than Claude Opus 5.5?
Yes on sticker input and output in this catalog. Cache reads tie at $0.20 per 1M. Measured task cost can still favor either side depending on token burn and long-context mix.
Which is cheaper for agents?
Below 272K input, Sol usually wins the meter on equal token counts. If Opus finishes with fewer steps or you need Claude tooling, measure end-to-end cost, not stickers alone.
Do both models have 1M context?
Roughly yes. Sol publishes about 1.05M with a pricing cliff past 272K input. Opus publishes 1M at standard rates across the window.
Can I compare Exact token counts across both?
OpenAI can be Exact in TokenCalculator. Claude stays Approx in-browser. Equalize with provider count APIs when the budget is contractual.
Why is my Claude Code bill still high if Sol is half Opus?
Agents burn tokens on tools, retries, and long prefixes. Cache writes, Fast mode, and higher step counts can erase sticker savings. Price a full agent trace, not one turn.
Where is GPT-6 Astra and Fable 5.1?
Both list at $10 / $50. Use them when Sol or Opus 5.5 still fail hard evals. See the Astra vs Fable guide for that premium tier.
Are these rates live?
No. Curated catalog rates last verified 23 Sep 2026. Confirm on OpenAI and Anthropic pricing pages.
What should I open first?
Paste one production prompt into the cost calculator twice: once on Sol, once on Opus 5.5. Then open the compare pair URL for a side-by-side catalog view.
Next steps
- GPT-6 Sol pricing
- Claude Opus 5.5 pricing
- GPT-6 Astra vs Claude Fable 5.1
- Sol model page
- Opus 5.5 model page
- How we verify rates
Related Sep 2026 pricing guides
Frontier rate cards, cost-per-task math, and long-context cliffs. Cross-link these when you compare Sol, Luna, Opus 5.5, Grok 4.7, or Astra.