# DeepSeek V4.1 Flash Fast vs GPT OSS 120B

As of November 12, 2026, DeepSeek V4.1 Flash Fast costs 67% more per input token than GPT OSS 120B ($0.05 vs $0.03 per 1M) and has a 1M-token context window versus 131K.

- Page: https://models.litellm.ai/compare/deepseek-v4.1-flash-fast-vs-gpt-oss-120b
- DeepSeek V4.1 Flash Fast: https://models.litellm.ai/models/deepseek-v4.1-flash-fast
- GPT OSS 120B: https://models.litellm.ai/models/gpt-oss-120b

## Side by side

| | DeepSeek V4.1 Flash Fast | GPT OSS 120B |
|---|---|---|
| Input, per 1M tokens | $0.05 | $0.03 |
| Output, per 1M tokens | $0.15 | $0.17 |
| Cache read, per 1M tokens | $0.003 | – |
| Cache write, per 1M tokens | – | – |
| Context window | 1,048,576 tokens | 131,000 tokens |
| Max output | 262,144 tokens | 131,072 tokens |
| Image input | No | – |
| Tool calling | Yes | Yes |
| Structured output (JSON) | Yes | Yes |
| Prompt caching | Yes | Yes |
| Reasoning | Yes | Yes |
| Providers on LiteLLM | 4 | 28 |
| Price shown is from | Refuseless | Weights & Biases |
| Added to LiteLLM | September 29, 2026 | August 2025 |

Headline prices in USD per 1M tokens, from LiteLLM's model price file.

## Cheapest provider for each

- DeepSeek V4.1 Flash Fast: Refuseless at $0.05 input per 1M tokens (`refuseless/deepseek-v4.1-flash-fast`)
- GPT OSS 120B: Weights & Biases at $0.03 input per 1M tokens (`wandb/openai/gpt-oss-120b`)

## When to pick which

- DeepSeek V4.1 Flash Fast: Costs 12% less per output token: $0.15 vs $0.17 per 1M.
- DeepSeek V4.1 Flash Fast: Larger context window: 1,048,576 vs 131,000 tokens.
- GPT OSS 120B: Costs 40% less per input token: $0.03 vs $0.05 per 1M.
- GPT OSS 120B: Available from 28 providers through LiteLLM, vs 4.

## FAQ

### Which is cheaper, DeepSeek V4.1 Flash Fast or GPT OSS 120B?

GPT OSS 120B is cheaper at 3 input tokens per output token: $0.065 per 1M tokens blended ($0.03 input, $0.17 output), versus $0.075 ($0.05 and $0.15) for DeepSeek V4.1 Flash Fast, as of November 12, 2026.

### Which has the larger context window, DeepSeek V4.1 Flash Fast or GPT OSS 120B?

DeepSeek V4.1 Flash Fast has the larger context window: 1,048,576 tokens, versus 131,000 for GPT OSS 120B.

### Can I switch from DeepSeek V4.1 Flash Fast to GPT OSS 120B without changing my code?

Yes. Through LiteLLM both use the OpenAI format, so switching means changing the model name from "refuseless/deepseek-v4.1-flash-fast" to "wandb/openai/gpt-oss-120b", or pointing a LiteLLM gateway model alias at the other model. You can also use one as a fallback for the other.