gpt-oss-120b vs DeepSeek V4.1 Flash
An open-weight model with no first-party price against the cheapest first-party API from DeepSeek. Both list prices from the makers’ own pages, and what three everyday jobs cost on each.
US dollars, standard rate, shortest context band. Price only: this page does not rank quality.
- gpt-oss-120b, per M tokens
- No list price
- DeepSeek V4.1 Flash, per M tokens
- $0.30 / $1.20
3,000 tokens in and 400 out each, at list price.
Per million tokens, DeepSeek V4.1 Flash costs $0.30 in and $1.20 out. gpt-oss-120b has no list price: OpenAI publishes its weights but sells no API for it, so the cost depends on the host. gpt-oss-120b reads up to 131K tokens at once, DeepSeek V4.1 Flash up to 1M.
Side by side
Each maker’s published rate for its standard tier. Cached input is what a repeated prompt prefix costs once the provider has stored it.
| Fact | gpt-oss-120b | DeepSeek V4.1 Flash |
|---|---|---|
| Maker | OpenAI | DeepSeek |
| Tier | Workhorses | Small and fast |
| Input, per M tokens | Not published | $0.30 |
| Output, per M tokens | Not published | $1.20 |
| Cached input | Not published | $0.006 |
| Context window | 131K | 1M |
| Released | 5 Aug 2025 | 10 Sep 2026 |
| Weights | Open | Open |
The small print
What each base rate leaves out, from the makers’ own pages: surcharges, discounts, promotions and cache pricing.
- gpt-oss-120b
- No first-party price: open-weight model (Apache 2.0) that OpenAI does not serve on its API. Cost depends on the third-party host. Specs from https://developers.openai.com/api/docs/models/gpt-oss-120b; release date from the OpenAI model card dated August 5, 2025.
- DeepSeek V4.1 Flash
- Peak-hour rate, recorded as the list price. Off-peak is half: $0.15 / $0.60, cache hit $0.003. API name deepseek-flash. Max output 384K. DeepSeek’s pricing page
Other comparisons
Every head to head on the list that involves gpt-oss-120b or DeepSeek V4.1 Flash.
Run DeepSeek V4.1 Flash for a quarter of list price
AIGROW API credit covers DeepSeek V4.1 Flash and is metered at the list prices above: $25 buys $100 of usage.
Prices checked 22 September 2026