DeepSeek V4 Flash vs GPT OSS 120B
As of October 21, 2026, DeepSeek V4 Flash costs 900% more per input token than GPT OSS 120B ($0.30 vs $0.03 per 1M) and has a 1M-token context window versus 131K.
DeepSeek V4 Flash vs GPT OSS 120B side by side
| DeepSeek V4 Flash | GPT OSS 120B | |
|---|---|---|
| Input, per 1M tokens | $0.30 | $0.03 |
| Output, per 1M tokens | $1.20 | $0.17 |
| Cache read, per 1M tokens | $0.006 | – |
| Cache write, per 1M tokens | $0 | – |
| Context window | 1,000,000 tokens | 131,000 tokens |
| Max output | 393,216 tokens | 131,072 tokens |
| Image input | Yes | – |
| Tool calling | Yes | Yes |
| Structured output (JSON) | Yes | Yes |
| Prompt caching | Yes | Yes |
| Reasoning | Yes | Yes |
| Providers on LiteLLM | 23 | 24 |
| Price shown is from | DeepSeek | Weights & Biases |
| Added to LiteLLM | June 2026 | August 2025 |
Cheapest provider for each
- DeepSeek V4 Flash: DeepInfra at $0.08 input and $0.18 output per 1M tokens (
deepinfra/deepseek-ai/DeepSeek-V4-Flash-0731) - GPT OSS 120B: Weights & Biases at $0.03 input and $0.17 output per 1M tokens (
wandb/openai/gpt-oss-120b)
When to pick which
Pick DeepSeek V4 Flash for
- Larger context window: 1,000,000 vs 131,000 tokens.
- Returns up to 393,216 tokens per response, vs 131,072.
Pick GPT OSS 120B for
- Costs 90% less per input token: $0.03 vs $0.30 per 1M.
From differences in the data above only; where the data is equal, no reason is given.
Call DeepSeek V4 Flash or GPT OSS 120B with LiteLLM
Both use the OpenAI format through LiteLLM, so switching is a model name change. Set each provider's API key in the environment first.
from litellm import completion
messages = [{"role": "user", "content": "Hello!"}]
# DeepSeek V4 Flash
response = completion(model="deepseek-v4-flash", messages=messages)
# GPT OSS 120B
response = completion(model="wandb/openai/gpt-oss-120b", messages=messages)
# DeepSeek V4 Flash, falling back to GPT OSS 120B if the call fails
response = completion(model="deepseek-v4-flash", messages=messages, fallbacks=["wandb/openai/gpt-oss-120b"])FAQ
Which is cheaper, DeepSeek V4 Flash 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 $0.525 ($0.30 and $1.20) for DeepSeek V4 Flash, as of October 21, 2026.
Which has the larger context window, DeepSeek V4 Flash or GPT OSS 120B?
DeepSeek V4 Flash has the larger context window: 1,000,000 tokens, versus 131,000 for GPT OSS 120B.
Can I switch from DeepSeek V4 Flash to GPT OSS 120B without changing my code?
Yes. Through LiteLLM both use the OpenAI format, so switching means changing the model name from "deepseek-v4-flash" 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.