GPT-5 vs gpt-oss-20b
Benchmarks, API pricing and specs, head to head. Data updated 2026-06-10.
OpenAI · Aug 2025
OpenAI's August 2025 unified flagship that merged the GPT and o-series reasoning lines into one model with selectable effort.
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 39x cheaper per blended million tokens. GPT-5 also takes 400K 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
| GPT-5 | gpt-oss-20b | |
|---|---|---|
| modhub Index | 70.7 | — |
| Input price / 1M | $1.25 | $0.05 |
| Output price / 1M | $10 | $0.2 |
| Context window | 400K | 131K |
| Max output | 128K | 131K |
| Open weights | no | yes (Apache 2.0) |
| Reasoning model | yes | yes |
| Multimodal input | text, image | text |
| Knowledge cutoff | Sep 2024 | Jun 2024 |
| Released | Aug 2025 | Aug 2025 |
| Example monthly cost* | $27.50 | $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, GPT-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 39x cheaper per blended million tokens. GPT-5 also takes 400K 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, GPT-5 or gpt-oss-20b?
- GPT-5 costs $1.25/$10 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 $27.50 versus $0.8.
- Which model is better for coding, GPT-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.