What hardware do you need to run gpt-oss-20b?
gpt-oss-20b at MXFP4 is 12 GB of weights, with a context ceiling of 128k tokens. Punchy for 12 GB, with adjustable reasoning effort. High effort is slow; low effort is shallow.
How good is it, really?
On the Artificial Analysis Intelligence Index v4.3 it scores 9 (high reasoning effort; 10 at low), which puts it in the Below every hosted tier band. Fine for simple, well-specified tasks. Noticeably less capable than anything the big labs sell today. Score source. See the whole table.
- Summarising — good
- Translation — usable
- Everyday coding — good
- Reasoning & maths — usable
- Agentic work — usable
What it costs either way
Renting the same model costs $0.02 per million input tokens and $0.1 per million output (OpenRouter, cheapest active endpoint, checked 2026-09-03). Buying a machine only beats that if you use it hard enough, for long enough, that the hardware price divides down below the rental bill.
Machines that run it
| Machine | Price | Speed at 32k | Pay-back | |
|---|---|---|---|---|
| Mac mini M6, 24GB | $1,099 | 18 tok/s estimated | Pays back in 426 years | Run the numbers |
| Strix Halo Framework Desktop, 32GB | $1,269 | 49 tok/s estimated | Pays back in 410 years | Run the numbers |
| MacBook Pro M5 (14-inch), 32GB | $2,399 | 16 tok/s estimated | Pays back in 1,018 years | Run the numbers |
| Mac Studio M5 Max, 36GB | $2,499 | 48 tok/s estimated | Pays back in 854 years | Run the numbers |
| DGX Spark GB10 Grace Blackwell, 128GB | $4,699 | 60 tok/s measured | Pays back in 1,459 years | Run the numbers |
One machine per family, cheapest first. Speeds are measured where a public benchmark exists and estimated from memory bandwidth otherwise; the calculator says which for any configuration.
The specifics
- Parameters
- 20.9B, of which 3.6B are active per token
- Quantisation
- MXFP4
- Weights on disk
- 12 GB
- KV cache
- 0.8 GB at 32k context — Half the layers use a 128-token sliding window; KV cache is tiny.
- Maximum context
- 128k tokens (128k)
- Licence
- Apache 2.0
- Sources
- source 1, source 2