gpt-oss-20b: how much memory, and what runs it
gpt-oss-20b is a mid-size AI model you can download and run on your own computer. It is a mixture of experts: all of it has to fit in memory, but it uses only a small part for each word. It needs about 13 GB of memory at standard quality.
Memory needed
About 13 GB
At standard quality, with room for a conversation of about 12 pages.
Machines that run gpt-oss-20b
Each of these holds the whole model in memory. We do not estimate a speed for this kind of model (a mixture of experts), so these are simply the cheapest.
EU shops · In the US? Switch the currency to USD.US shops · In Europe? Switch the currency to EUR.
Mac mini M6 32GB
32 GB shared memory
$1,416€1,530estimate
Machine details →Mac Studio M4 Max 36GB
36 GB shared memory · second-hand
$2,116€1,890usedunverified
Machine details →Mac mini M4 Pro 64GB
64 GB shared memory · second-hand
$2,116€1,890usedunverified
Machine details →Mid-range PC with RTX 4060 Ti 16GB
16 GB graphics memory
$1,849€1,999estimate
Machine details →The buttons look up the graphics card, the part of this PC worth comparing.
Used PC with RTX 3090 24GB
24 GB graphics memory · second-hand
$2,388€2,324estimateused parts
Machine details →The buttons look up the graphics card, the part of this PC worth comparing.
Where our price is for a used card or Mac, these shops mostly sell new ones, so their price can be higher.
About these prices
Each price is the amount we last wrote down for that machine, with its date on the machine page. "Estimate" is our own figure: for a complete PC we add our estimate for the other parts to the graphics card price, and some Mac prices are estimates, not a checked shop listing. "Used" is a second-hand price. "Unverified" means we have no checked shop listing for that exact amount. The shop buttons open a search for that machine at each shop, so you see today's price there. Prices excl. shipping. Euro prices incl. VAT. Dollar prices are converted from our euro prices without EU VAT, before US sales tax.
Speeds and memory are our estimate from the hardware specs, not a measured test. Prices are dated and may change. How we calculate
Memory at each quality level
A lower quality level makes the model smaller, so it fits on a smaller machine. Standard (Q4) is what most people run.
| Quality | Memory needed |
|---|---|
| Q4 · standard (smallest that keeps quality) | 13.1 GB |
| Q5 · a bit sharper, a bit bigger | 14.8 GB |
| Q8 · near full quality, almost twice Q4 | 14.8 GB |
| FP16 · full quality, over three times Q4 | 14.8 GB |
With a conversation of 8,192 tokens · about 12 pages of text.
How we worked this out
At standard quality: 12.1 GB for the model itself (a measured file), 0.2 GB for a conversation of 8,192 tokens, and 0.8 GB for the software.
Size source: huggingface.co/openai/gpt-oss-20b. 21B parameters in total, 3.6B used for each word. The memory counts the total.
OpenAI's smaller open model for chat, code and tool use. It ships in 4-bit, so the official file is about 12 GB and fits a 16 GB graphics card. Even the full-quality file is only 13.8 GB, so our higher quality levels use that file's size. Lower-quality versions we checked keep that 4-bit core and save under 1 GB.
Licence
Commercial use: yes
Commercial use allowed. Keep the licence and copyright notice when you share the weights.
Licence: Apache-2.0 · checked 21 Oct 2026
Our reading of the licence, not legal advice.
Will gpt-oss-20b run on my graphics card?
Common questions
- How much memory does gpt-oss-20b need?
- About 13.1 GB at standard quality (Q4) with a conversation of 8,192 tokens: 12.1 GB for the model itself, 0.2 GB for the conversation and 0.8 GB for the software. The model size is a measured file; the conversation and software parts are our estimate.
- Does gpt-oss-20b fit on a single 24 GB graphics card?
- Yes, by our estimate. It needs about 13.1 GB, and we count 23.4 GB of a 24 GB card as usable.
- Are the speeds measured?
- We do not show a speed for this model. It is a mixture-of-experts model, and our estimate would not be reliable for that design.