Claude Sonnet 4.5 vs GPT-5.5 Pro
Benchmarks, API pricing and specs, head to head. Data updated 2026-06-10.
Anthropic · Sep 2025
The model that made 30-hour autonomous coding sessions real — 77.2% SWE-bench Verified and a 1M-token context beta at $3/$15.
OpenAI · Apr 2026
The maximum-compute tier of GPT-5.5 for the hardest research, math and engineering problems, at a steep per-token premium.
The verdict
These two models don't yet share verified results on the benchmarks we track, so judge them on specs, pricing and intended use. On price the gap is dramatic: Claude Sonnet 4.5 works out roughly 11x cheaper per blended million tokens. GPT-5.5 Pro also takes 1M of context versus 200K for Claude Sonnet 4.5.
Specs & pricing
| Claude Sonnet 4.5 | GPT-5.5 Pro | |
|---|---|---|
| modhub Index | 65.5 | — |
| Input price / 1M | $3 | $30 |
| Output price / 1M | $15 | $180 |
| Context window | 200K | 1M |
| Max output | 64K | 128K |
| Open weights | no | no |
| Reasoning model | yes | yes |
| Multimodal input | text, image | text, image |
| Knowledge cutoff | Jan 2025 | Jan 2026 |
| Released | Sep 2025 | Apr 2026 |
| Example monthly cost* | $52.50 | $570.00 |
* 10M input + 1.5M output tokens per month at list prices, no caching. Green = better value on that row.
Frequently asked questions
- Which is better, Claude Sonnet 4.5 or GPT-5.5 Pro?
- These two models don't yet share verified results on the benchmarks we track, so judge them on specs, pricing and intended use. On price the gap is dramatic: Claude Sonnet 4.5 works out roughly 11x cheaper per blended million tokens. GPT-5.5 Pro also takes 1M of context versus 200K for Claude Sonnet 4.5.
- Which is cheaper, Claude Sonnet 4.5 or GPT-5.5 Pro?
- Claude Sonnet 4.5 costs $3/$15 per million input/output tokens, while GPT-5.5 Pro costs $30/$180. For a typical workload of 10M input and 1.5M output tokens per month, that's $52.50 versus $570.00.
- Which model is better for coding, Claude Sonnet 4.5 or GPT-5.5 Pro?
- We don't yet track SWE-bench Verified results for both models; check their individual pages for coding-related scores.