What hardware do you need to run GLM-5.3-Flash?

GLM-5.3-Flash at UD-Q4_K_M is 189 GB of weights, with a context ceiling of 1M tokens. Ties Qwen3.8 Flash for the strongest open model, but needs a 256 GB machine. On the cheapest machine that runs it, a Mac Studio M5 Ultra, 256GB, it generates 32 tok/s at 32k of context, worked out from memory bandwidth.

How good is GLM-5.3-Flash, really?

On the Artificial Analysis Intelligence Index v4.3 it scores 42, which puts it in the Sonnet-class band. In the same league as the labs' mainstream models on this index. See the whole table.

Head to head with its neighbours on the leaderboard: vs MiniMax M3.1 Flash above it, vs Ling 3.1 flash below. One more model needs much the same memory at 32k of context: vs Tencent Hy3.

What GLM-5.3-Flash costs either way

Renting the same model costs $0.0513 per million input tokens and $0.0701 per million output (OpenRouter, cheapest active endpoint, checked 2026-10-29). 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. What a million tokens costs each way puts the two prices side by side.

Machines that run GLM-5.3-Flash

The Mac Studio M5 Ultra, 256GB holds it to 128k, and it is the machine's memory that stops it there, not the model's 1M limit.

The table is the cheapest machine in each family, not the only one that runs it: 4 of the 56 machines on this site hold it at 32k. Within a family only memory decides, so that is every Mac Studio with 256GB or more. One table sets every machine against the others: price, the memory its GPU can use, what it holds and how long it takes to pay for itself.

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 longest context is the longest setting the calculator offers that the machine still holds this model at, cache included, and no machine is shown taking it past its own 1M limit. Each one opens the calculator on that machine at that length.

For scale, the calculator starts from 80 tok/s for a hosted API and times a local machine against it. The one above does not reach it, at 32 tok/s.

The cheapest machine that runs it is sold with 256 GB. There is a page on what 256 GB runs, machine by machine: it names the 2 machines here sold at that size, and the 44 current models the roomiest of them holds at 32k, this one among them.

Run GLM-5.3-Flash at 128k on the Mac Studio M5 Ultra, 256GB

How much memory does GLM-5.3-Flash need at 256k?

Every figure above is priced at 32k of context. At 256k, the longest the calculator offers, GLM-5.3-Flash needs 193.4 GB rather than 189.5 GB. The weights are the same either way; the key-value cache goes from 0.6 GB to 4.4 GB.

No machine here that is still sold at a published price holds GLM-5.3-Flash at 256k. One of the 37 machines here still sold at a published price holds it at 32k, and it is the Mac Studio M5 Ultra, 256GB at $10,799. Two machines here do hold it there: the Mac Studio M5 Ultra, 512GB, on sale with no published price; the Mac Studio M3 Ultra, 512GB, no longer sold, at the $9,499 it launched at.

The machines that miss GLM-5.3-Flash, and what they run

Of the machines here with a published price that are still sold, every one but the Mac Studio M5 Ultra, 256GB misses GLM-5.3-Flash, and none of them misses by a window: its 189 GB of weights are larger than the usable memory in every one of them, before a single token of key-value cache. The DGX Spark GB10 Grace Blackwell, 128GB comes nearest, 69.6 GB short at 4k, the shortest window on the list. Qwen3.8 27B is the strongest model seven of the eight hold, and it scores 34 on the intelligence index against this model's 42.

Three machines here do hold GLM-5.3-Flash at 32k, and none of them is an answer to what to buy, which is the question the rest of this page asks: the Mac Studio M3 Ultra, 256GB and the Mac Studio M3 Ultra, 512GB, no longer sold, at the $7,099 and $9,499 they launched at, and the Mac Studio M5 Ultra, 512GB, on sale with no published price. They are sold with 256 GB and 512 GB of memory and hand a model 192 GB to 384 GB of it, against the 190 GB GLM-5.3-Flash needs at 32k.

One machine per family, the largest configuration in each that still misses, nearest first. Short by is the weights plus the key-value cache at 4k measured against the memory that machine's GPU can address, which that machine's own page gives. The last column is the highest-scoring current model the machine holds at 32k.

Price the DGX Spark GB10 Grace Blackwell, 128GB on Qwen3.8 27B instead

The specifics

Parameters

321.3B, of which 18B are active per token

Quantisation

UD-Q4_K_M

Weights on disk

189 GB

KV cache

0.6 GB at 32k context — 34 of 45 layers use linear attention with a fixed state; the other 11 use latent attention with no RoPE part (1,024 B) plus a sparse-attention indexer (514 B). Note this is the figure for vLLM or SGLang: the reference Transformers code expands the latent before caching and uses far more. How weights and cache add up.

Maximum context

1M tokens

Licence

MIT

Sources

zai-org/GLM-5.3-Flash