Claude Sonnet 4.5 vs gpt-oss-20b
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 · Aug 2025
The small gpt-oss variant that runs on a 16GB consumer GPU or laptop — local reasoning for everyone, Apache 2.0 licensed.
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: gpt-oss-20b works out roughly 69x cheaper per blended million tokens. Claude Sonnet 4.5 also takes 200K of context versus 131K for gpt-oss-20b. And gpt-oss-20b is open-weights (Apache 2.0), so it can be self-hosted — a structural advantage if data control or vendor independence matters.
Specs & pricing
| Claude Sonnet 4.5 | gpt-oss-20b | |
|---|---|---|
| modhub Index | 65.5 | — |
| Input price / 1M | $3 | $0.05 |
| Output price / 1M | $15 | $0.2 |
| Context window | 200K | 131K |
| Max output | 64K | 131K |
| Open weights | no | yes (Apache 2.0) |
| Reasoning model | yes | yes |
| Multimodal input | text, image | text |
| Knowledge cutoff | Jan 2025 | Jun 2024 |
| Released | Sep 2025 | Aug 2025 |
| Example monthly cost* | $52.50 | $0.8 |
* 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-oss-20b?
- 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: gpt-oss-20b works out roughly 69x cheaper per blended million tokens. Claude Sonnet 4.5 also takes 200K of context versus 131K for gpt-oss-20b. And gpt-oss-20b is open-weights (Apache 2.0), so it can be self-hosted — a structural advantage if data control or vendor independence matters.
- Which is cheaper, Claude Sonnet 4.5 or gpt-oss-20b?
- Claude Sonnet 4.5 costs $3/$15 per million input/output tokens, while gpt-oss-20b costs $0.05/$0.2. For a typical workload of 10M input and 1.5M output tokens per month, that's $52.50 versus $0.8.
- Which model is better for coding, Claude Sonnet 4.5 or gpt-oss-20b?
- We don't yet track SWE-bench Verified results for both models; check their individual pages for coding-related scores.