GPT OSS 20B

by OpenAI

GPT OSS 20B is a model from OpenAI, released on August 5, 2025. It has a 131K-token context window and can generate up to 131K output tokens. API pricing is $0.03 per 1M input tokens and $0.14 per 1M output tokens. It ranks #133 of 220 models by Intelligence Score with a score of 18.

The gpt-oss-20b model (technically 20.9B parameters) achieves near-parity with OpenAI o4-mini on core reasoning benchmarks, while running efficiently on a single 80 GB GPU. The gpt-oss-20b model delivers similar results to OpenAI o3‑mini on common benchmarks and can run on edge devices with just 16 GB of memory, making it ideal for on-device use cases, local inference, or rapid iteration without costly infrastructure. Both models also perform strongly on tool use, few-shot function calling, CoT reasoning (as seen in results on the Tau-Bench agentic evaluation suite) and HealthBench (even outperforming proprietary models like OpenAI o1 and GPT‑4o). Note: While referred to as '20b' for simplicity, it technically has 20.9B parameters.

Key specs

ProviderOpenAI
Release date2025-08-05
Licenseopen source
Context window131K tokens
Max output131K tokens
Input price$0.03 / 1M tokens
Output price$0.14 / 1M tokens
Intelligence Score18

Quick answers

What is the context window of GPT OSS 20B?

GPT OSS 20B has a context window of 131K tokens, with a maximum output of 131K tokens per response.

How much does GPT OSS 20B cost?

GPT OSS 20B costs $0.03 per 1M input tokens and $0.14 per 1M output tokens through the API.

Is GPT OSS 20B open source?

Yes. GPT OSS 20B is an open model released under the open source license.

When was GPT OSS 20B released?

OpenAI released GPT OSS 20B on August 5, 2025.

How does GPT OSS 20B compare to Claude Opus 5.5 (Reasoning)?

GPT OSS 20B scores 18 on the Intelligence Score versus 60.5 for Claude Opus 5.5 (Reasoning), the current #1. Input pricing is $0.03 vs $4 per 1M tokens.

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