# OpenAI GPT-OSS 120B vs Claude Sonnet 5

On provider list prices, OpenAI GPT-OSS 120B costs $0.15 per million input tokens against $3 for Claude Sonnet 5: 20.0x apart. Output is $0.60 against $15 (25.0x). On Allocate both bill at list plus the 7% transaction fee.

## Specifications

| | OpenAI GPT-OSS 120B | Claude Sonnet 5 |
| --- | --- | --- |
| Lab | OpenAI | Anthropic |
| Access | Open weights | API only |
| Context window | 128K tokens | 1M tokens |
| List price, input | $0.15 / M tokens | $3 / M tokens |
| List price, output | $0.60 / M tokens | $15 / M tokens |
| Cached input | n/a | n/a |
| License | Custom license | Proprietary API |
| Fine-tunable | Yes | No |

Specifications and provider list prices from the Allocate catalog, checked 2026-07-08. Billed price is list plus the 7% transaction fee.

## What the numbers say

Take 1,000,000 requests a month at 1,200 input and 350 output tokens each. That workload costs $390 a month on OpenAI GPT-OSS 120B and $8,850 on Claude Sonnet 5 at list: a gap of $8,460, or 22.7x.

Claude Sonnet 5 reads 1M tokens per request against 128K for OpenAI GPT-OSS 120B, 7.6x the window. That decides which one can take whole documents without splitting them.

## Choose OpenAI GPT-OSS 120B for

- The lower list price ($0.15 in / $0.60 out per M tokens)
- Open weights you can fine-tune and own

## Choose Claude Sonnet 5 for

- Judgment calls with policy context
- Customer-facing writing
- Review and escalation flows

## Common questions

### Which is cheaper, OpenAI GPT-OSS 120B or Claude Sonnet 5?

OpenAI GPT-OSS 120B, on this workload shape. At list prices it is $0.15/$0.60 per million tokens in and out against $3/$15 for Claude Sonnet 5. Billed on Allocate: $0.16/$0.64 against $3.21/$16.05, list plus 7%.

### Which has the bigger context window?

Claude Sonnet 5: 1,000,000 tokens (1M) against 131,072 (128K) for OpenAI GPT-OSS 120B.

### Can I fine-tune OpenAI GPT-OSS 120B or Claude Sonnet 5?

OpenAI GPT-OSS 120B publishes open weights (Custom license) and can be fine-tuned on your own data. Claude Sonnet 5 is a closed model served over API; its weights are not available.

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[HTML page](https://allocate.network/compare/openai-gpt-oss-120b-vs-sonnet-5) · [OpenAI GPT-OSS 120B](https://allocate.network/models/openai-gpt-oss-120b.md) · [Claude Sonnet 5](https://allocate.network/models/sonnet-5.md) · [Machine-readable catalog](https://allocate.network/catalog.json)