Claude Sonnet 5.5 vs GPT-6.1 Sol.
Verdict by category, tale of the tape, shared benchmarks only, and cost at three workloads — all from the tracked data.
Verdict by category
| Category | Claude Sonnet 5.5 | GPT-6.1 Sol | Winner |
|---|---|---|---|
| League Score | 86.9 | 93.8 | GPT-6.1 Sol |
| Coding (SWE-bench %) | — | — | — |
| Reasoning (GPQA %) | — | — | — |
| Context (tokens) | 1000000 | 1050000 | GPT-6.1 Sol |
| Speed (tok/s) | — | — | — |
| Price (blended $/1M) | $4.00 | $4.00 | GPT-6.1 Sol (cheaper) |
Tale of the tape
| Spec | Claude Sonnet 5.5 | GPT-6.1 Sol |
|---|---|---|
| Maker | Anthropic | OpenAI |
| Released | Sep 28, 2026 | Sep 29, 2026 |
| League Score | 87 | 94 |
| Context | 1,000,000 tokens | 1,050,000 tokens |
| Max output | 128,000 | 128,000 |
| $/1M input | $2.00 | $2.00 |
| $/1M output | $10.00 | $10.00 |
| Weights | Closed | Closed |
| Speed | — | — |
Head-to-head benchmarks (shared only)
| Benchmark | Claude Sonnet 5.5 | GPT-6.1 Sol |
|---|---|---|
| LiveBench overall | 82.5 | 85.4 |
Cost at three workloads
| Workload | Claude Sonnet 5.5 | GPT-6.1 Sol |
|---|---|---|
| Light — 1M in / 250K out | $4.50 | $4.50 |
| Standard — 10M in / 2.5M out | $45.00 | $45.00 |
| Long-context — 50M in / 5M out | $150.00 | $150.00 |
The pick
Pick GPT-6.1 Sol if you want the higher overall League Score; you need the bigger context window.
All figures from the model database — sources and dates on each model page. Cost your own workload or compare a different pair.
Frequently asked questions
Which is better overall, Claude Sonnet 5.5 or GPT-6.1 Sol?
GPT-6.1 Sol leads on overall League Score, 94 to 87 — a gap of 7 points on a composite of sourced benchmarks. That is overall form, not every category: check the per-category verdicts before choosing.
Which is cheaper, Claude Sonnet 5.5 or GPT-6.1 Sol?
They cost the same on our blended measure: $4.00 per 1M tokens each.
Which has the bigger context window, Claude Sonnet 5.5 or GPT-6.1 Sol?
GPT-6.1 Sol, with 1.1M of context against 1M for Claude Sonnet 5.5.
Are Claude Sonnet 5.5 and GPT-6.1 Sol open source?
Claude Sonnet 5.5 is closed weights — API access only; GPT-6.1 Sol is closed weights — API access only.