GLM-4.5-Air GPU requirements: 55.2 GB at 4-bit, 221 GB at BF16
GLM-4.5-Air needs 221 GB of GPU memory for its weights at BF16, 110 GB at FP8 and 55.2 GB at 4-bit, plus 6.17 GB of KV cache for a 32K context. The cheapest node that runs it here is 1× A100 PCIe 80GB at 4-bit, for $0.09 an hour on spot.
Weights plus a 32K 16-bit KV cache, with 10% of the node's memory kept free. Billed per minute.
- Parameters
- 106B12B active per token
- Weights, 4-bit
- 55.2 GBBF16: 221 GB
- KV cache, 32K
- 6.17 GBOne sequence, 16-bit cache
- Context window
- 128KNative
How much VRAM GLM-4.5-Air needs, format by format.
Weights are parameters × bytes per parameter. Each context column adds the KV cache of one sequence of that length.
| Format | Weights | + 8Kcontext | + 32Kcontext | + 128Kcontext | Cheapest node, 32K |
|---|---|---|---|---|---|
| BF16Published weights, fine-tuning | 221 GB | 222 GB | 227 GB | 246 GB | 4× A100 PCIe 80GB · $0.36/h |
| FP8Hopper, Ada, Blackwell, MI300 | 110 GB | 112 GB | 117 GB | 135 GB | 4× L40 · $0.36/h |
| 4-bitAWQ, GPTQ, GGUF Q4 | 55.2 GB | 56.8 GB | 61.4 GB | 79.9 GB | 1× A100 PCIe 80GB · $0.09/h |
The serving engine adds its own buffers, and an 8-bit KV cache halves the context columns. We keep 10% of a node's memory free when we say a model fits. Speed is a separate question: it follows memory bandwidth and, for a mixture of experts, the active parameters.
GPUs that run GLM-4.5-Air, cheapest first.
For each format, the smallest node of each GPU model that holds the weights and a 32K context, sorted by spot price. One row per GPU model; larger nodes of the same GPU work too.
| Format | GPU | GPU memory | Spot | On-demand | 730 h spot | Action |
|---|---|---|---|---|---|---|
| 4-bit | 1× A100 PCIe 80GBAmpere · 61.4 GB needed | 80 GB | $0.09 | $0.19 | $65.70 | Deploy |
| 4-bit | 2× A40Ampere · 61.4 GB needed | 96 GB | $0.12 | $0.18 | $87.60 | Deploy |
| 4-bit | 2× A100 40GBAmpere · 61.4 GB needed | 80 GB | $0.18 | $0.34 | $131.40 | Deploy |
| 4-bit | 2× L40Ada Lovelace · 61.4 GB needed | 96 GB | $0.18 | $0.38 | $131.40 | Deploy |
| FP8 | 4× L40Ada Lovelace · 117 GB needed | 192 GB | $0.36 | $0.76 | $262.80 | Deploy |
| FP8 | 4× RTX 6000 AdaAda Lovelace · 117 GB needed | 192 GB | $0.36 | $0.76 | $262.80 | Deploy |
| FP8 | 2× RTX PRO 6000 BlackwellBlackwell · 117 GB needed | 192 GB | $0.38 | $0.78 | $277.40 | Deploy |
| FP8 | 4× L40SAda Lovelace · 117 GB needed | 192 GB | $0.60 | $1.00 | $438.00 | Deploy |
| BF16 | 4× A100 PCIe 80GBAmpere · 227 GB needed | 320 GB | $0.36 | $0.76 | $262.80 | Deploy |
| BF16 | 8× A40Ampere · 227 GB needed | 384 GB | $0.48 | $0.72 | $350.40 | Deploy |
| BF16 | 8× A100 40GBAmpere · 227 GB needed | 320 GB | $0.72 | $1.36 | $525.60 | Deploy |
| BF16 | 8× L40Ada Lovelace · 227 GB needed | 384 GB | $0.72 | $1.52 | $525.60 | Deploy |
Spot capacity can be reclaimed with a 2-minute notice; for a live endpoint, use on-demand. How spot works · serving a language model.
What a long context costs in memory.
Grouped-query attention, 8 KV heads of 128 across 46 layers.
| Context | KV cache, 1 sequence | 8 sequences |
|---|---|---|
| 8K tokens | 1.54 GB | 12.3 GB |
| 32K tokens | 6.17 GB | 49.4 GB |
| 128K tokens | 24.7 GB | 198 GB |
Serving several users
KV cacheEvery concurrent request keeps its own cache, so memory for context grows with users × context length. A server batching 8 requests of 32K needs eight times the single-sequence figure — 49.4 GB here.
- Recommended node1× A100 PCIe 80GB
- Weights at 4-bit55.2 GB
- Context that fits, 1 sequence87K
Paged attention (vLLM, SGLang) allocates the cache in blocks as requests grow, so a node holds more short requests than the worst case suggests.
GLM-4.5-Air, as published.
- Developer
- Z.aiCompact GLM-4.5 for a single node
- Parameters
- 106B total, 12B active per token110B in the published checkpoint (embedding tables, prediction or vision modules included); memory figures use this count
- Architecture
- Mixture of experts, 46 layersGrouped-query attention, 8 KV heads of 128 across 46 layers
- Context window
- 131,072 tokensAs set in the published configuration
- Published format
- BF16, 221 GB
- Licence
- MIT
- Released
- 20 July 2025
- Source
- zai-org/GLM-4.5-Airconfig.json read 26 October 2026
Serve it with vLLM
template: vLLMOn 1× A100 PCIe 80GB, from the instance terminal:
$ vllm serve zai-org/GLM-4.5-Air \ --tensor-parallel-size 1 \ --max-model-len 32768
Very recent architectures need a recent vLLM; the model card gives the minimum version and any extra flags.
GLM-4.5-Air on a GPU — the questions that come up
How much VRAM does GLM-4.5-Air need?
For the weights alone: 221 GB at BF16, 110 GB at FP8 and 55.2 GB at 4-bit. Add 6.17 GB of KV cache for one 32K-token context, or 24.7 GB at the full 128K window, and keep about 10% of the memory free for activations.
Can GLM-4.5-Air run on a single GPU?
One RTX 4090 (24 GB): no. One RTX 5090 (32 GB): no. One H100 SXM (80 GB): yes, at 4-bit. One H200 SXM (141 GB): yes, at FP8. One B200 SXM (180 GB): yes, at FP8. Those answers assume a 32K context and the widest format that still fits.
What is the cheapest way to run GLM-4.5-Air?
Here, 1× A100 PCIe 80GB at 4-bit: $0.09 per hour on spot and $0.19 on-demand, billed per minute — $65.70 for a 730-hour month on spot. That node has 80 GB of GPU memory for the 61.4 GB this setup needs.
Does GLM-4.5-Air need less memory because only 12B parameters are active?
No. A mixture-of-experts model routes each token through a few experts, but every expert has to be resident in GPU memory, so the memory bill follows the 106B total. What the 12B active parameters change is the work per token: generation reads far less of the weights each step than a dense model of the same size would, which is why it is fast for its size.
Which format should I run it in?
BF16 keeps the published weights untouched and is the format for fine-tuning. FP8 halves the memory and runs in hardware on Hopper, Ada, Blackwell and MI300-class GPUs. 4-bit quantisation (AWQ, GPTQ, GGUF) quarters it, at a quality cost that is larger on small models than on big ones; check it against your own evaluation before relying on it.
How do I deploy it?
Pick the node in the table above and launch it with the vLLM template; the model downloads from Hugging Face (zai-org/GLM-4.5-Air) on first start. Spread the weights over the node with --tensor-parallel-size equal to the GPU count, and set --max-model-len to the context you need. New architectures need a recent vLLM: check the model card for the minimum version.
Sizing another model? GPU requirements for 64 open models · serving a language model · fine-tuning.
GLM-4.5-Air on 1× A100 PCIe 80GB for $0.09 an hour.
Launch the node with the vLLM template, point it at zai-org/GLM-4.5-Air, stop it when you are done. Prepaid, billed by the minute.
Billed per minute from the moment the instance is reachable. Minimum credit $30, no subscription.