AI model comparison
gpt-oss-120b vs gpt-oss-20b
Pricing, context window, benchmarks, and features compared side by side. Or skip the guesswork and send one prompt to both.
OpenAI
gpt-oss-120b
gpt-oss-120b is an open-weight, 117B-parameter Mixture-of-Experts (MoE) language model from OpenAI designed for high-reasoning, agentic, and general-purpose production use cases.
- Input / 1M
- $0.04
- Output / 1M
- $0.17
- Context
- 131K
OpenAI
gpt-oss-20b
gpt-oss-20b is an open-weight 21B parameter model released by OpenAI under the Apache 2.0 license.
- Input / 1M
- $0.02
- Output / 1M
- $0.09
- Context
- 131K
At a glance
Quick verdict
How the two models stack up on the things people ask about most.
Lower price
gpt-oss-20b
2.0x cheaper for a typical chat
Higher intelligence score
gpt-oss-120b
11.6 vs 10 on Artificial Analysis
Larger context window
Tie
131K vs 131K tokens
Newer release
gpt-oss-120b
Released August 5, 2025
Benchmarks
Benchmark scores
Independent scores from Artificial Analysis. Higher is better.
Intelligence index
gpt-oss-120b11.6gpt-oss-20b10Coding index
gpt-oss-120b30.4gpt-oss-20bNot availableAgentic index
gpt-oss-120b3.7gpt-oss-20bNot availablePricing
gpt-oss-120b vs gpt-oss-20b API pricing
Per-token API rates. Cheaper option highlighted.
| Metric | gpt-oss-120b | gpt-oss-20b |
|---|---|---|
| Input tokensPer 1M tokens | $0.04 | $0.02 |
| Output tokensPer 1M tokens | $0.17 | $0.09 |
| Cached input (read)Per 1M tokens | Not available | $0.01 |
| Cache writePer 1M tokens | Not available | Not available |
What it costs in practice
Estimated cost per 1,000 requests at standard rates. Coding and long-document figures also show the cost when the input is already cached.
Chat message
2K in, 500 out
gpt-oss-120b$0.16gpt-oss-20b$0.08Coding task
30K in, 4K out
gpt-oss-120b$1.79gpt-oss-20b$0.90$0.63 cachedLong document summary
150K in, 2K out
gpt-oss-120b$5.89gpt-oss-20b$2.88$1.53 cachedSpecs
Context window and capabilities
How much each model can read, how much it can write, and what it accepts as input.
| Metric | gpt-oss-120b | gpt-oss-20b |
|---|---|---|
| Context window | 131K tokens | 131K tokens |
| Max output | 118K tokens | 33K tokens |
| Input types | Text | Text |
| Output types | Text | Text |
| Reasoning effort levels | High, Medium, Low | High, Medium, Low |
| Default reasoning effort | Medium | Medium |
| Release date | August 5, 2025 | August 5, 2025 |
Features
Supported features
API features available for each model.
| Metric | gpt-oss-120b | gpt-oss-20b |
|---|---|---|
| Tool calling | Supported | Supported |
| Structured outputs | Supported | Supported |
| JSON mode | Supported | Supported |
| Reasoning | Supported | Supported |
| Temperature | Supported | Supported |
| Stop sequences | Supported | Supported |
| Deterministic seed | Supported | Supported |
| Verbosity control | Not supported | Not supported |
Keep exploring
More on these models
Other head-to-heads, the full model page, and the alternatives list for each model.
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- gpt-oss-120b vs Nemotron 3 Nano 30B A3B
Our take
gpt-oss-20b is 2.0x cheaper for a typical chat. gpt-oss-120b scores higher on the Artificial Analysis Intelligence Index (11.6 vs 10). The right pick depends on your workload, so the quickest way to settle it is to send the same prompt to both and compare.
FAQ
Frequently asked questions
Is gpt-oss-120b or gpt-oss-20b cheaper?
gpt-oss-20b is cheaper for a typical chat (2K input tokens and 500 output tokens). gpt-oss-20b costs $0.02 per 1M input tokens and $0.09 per 1M output tokens, while gpt-oss-120b costs $0.04 per 1M input tokens and $0.17 per 1M output tokens.
Which has a bigger context window, gpt-oss-120b or gpt-oss-20b?
gpt-oss-120b supports up to 131K tokens of context, compared with 131K for gpt-oss-20b.
Is gpt-oss-120b smarter than gpt-oss-20b?
On the Artificial Analysis Intelligence Index, gpt-oss-120b scores 11.6 and gpt-oss-20b scores 10, putting gpt-oss-120b ahead. Benchmarks don't capture everything, so the best test is running your own prompts through both.
Can I use gpt-oss-120b and gpt-oss-20b at the same time?
Yes. Shortcut Chat sends one prompt to multiple models at once, so you can see gpt-oss-120b and gpt-oss-20b answer side by side and keep the better response.
Why choose? Ask both.
Send one prompt to gpt-oss-120b and gpt-oss-20b at the same time. Compare the answers side by side and keep the best one.