Beam 1.0 501B-A23B

501B-A23B

Reflection Beam

Reflection AI's first open-weight model, released in October under Apache 2.0. It is a 501B text-only mixture-of-experts model with about 23B parameters active per token, built for coding and agent work, with a 1M-token window. Only 9 of its 52 layers keep a growing cache, so context costs little: at Q2_K (DevQuasar's 182 GB file) it needs about 191 GB at 4K, 196 GB at 128K and 230 GB across the full 1M window. That is comfortable on a 512 GB Mac Studio at any context and tight on a 256 GB one up to 128K. Unsloth's dynamic 4-bit UD-Q4_K_XL file (307 GB) works out to about 321 GB at 4K, which still fits the 512 GB Mac; Q8_0 (533 GB) fits no single machine in this index. Sizes come from the published GGUF files; Reflection's benchmark claims are its own and no per-level quality loss has been published.

⬇ 1.6K HF downloads♥ 139 likesreflection/Beam-1.0-501B-A23B· stats from 10/18/2026
Mac / Apple SiliconPro GPU

1049K

Max Context

2

Quant Variants

GGUF Q8_0

Best Quality

—

Accuracy Retained

Quantization Variants

Per-quant VRAM, quality loss, and inference speed on RTX 4090

Measured = run on this site · Estimated = not run here: calculated, or a figure this site has not verified · Community = public reports

FormatLevelBPWVRAMPPL LossSpeedSourceActions
GGUFQ2_K2.91190.9 GB——Estimated
CalcHF
GGUFQ8_08.5556.9 GB——Estimated
CalcHF
117B MoE

GPT-OSS 120B

OpenAI GPT-OSS

Pro GPUMac / Apple Silicon
58.5 GBmin VRAM100.0%accuracy

The big GPT-OSS (117B total / 5.1B active). Native MXFP4 checkpoint is ~61GB — fits one 80GB card or a 128GB unified-memory Mac. Partial offload on 24GB consumer cards is slow but works.

106B MoE

GLM-4.5-Air

Zhipu GLM-4.5

Pro GPUMac / Apple Silicon
34.8 GBmin VRAM97.6%accuracy

Zhipu's agentic/reasoning MoE (106B total / 12B active). Q4 ~64GB — the sweet spot is a 96GB+ unified Mac or 2× 48GB cards. Strong tool-calling for its class.

125B-A6B

Qwen3.8-Flash-Next

Qwen3.8

Mac / Apple SiliconPro GPU
79.3 GBmin VRAM—accuracy

Qwen's preview of its next architecture: a 125B mixture-of-experts model with about 6B parameters active per token. Released in August, it also carries a 51B n-gram lookup table. llama.cpp reads that table lazily from RAM or disk, so it never needs VRAM. It does need disk space and is bundled inside the GGUF files, which is why they are far larger than the sizes below. Only 12 of its 48 layers keep a growing KV cache, so even the full 256K window adds about 7.5 GB. At Q4_K_M it needs about 79 GB at 4K context and 87 GB at 256K, comfortable on a 128 GB Mac or DGX Spark. A single 24 or 32 GB card runs it only with experts offloaded to system RAM. llama.cpp supports it as `qwen4exp`. Sizes use the calculator's generic rates, since no file size isolates the model from the table, and no per-level quality loss has been published.

816B-A42B

Muse Spark Open 816B-A42B

Meta Muse

Mac / Apple SiliconPro GPU
318.9 GBmin VRAM—accuracy

Meta's largest open-weight model, released in October under the Muse Model License. It is an 816B mixture-of-experts model with about 42B parameters active per token, built for coding and agent work, with image and audio input. It is a single-machine model only at its smallest build. At Q2_K (ggml-org's 304 GB file) it needs about 319 GB at 4K context and still only 327 GB at 128K, because just 16 of its 62 layers keep a growing cache — comfortable on a 512 GB Mac Studio and tight across four 80 GB H100s. The full 1M window brings it to about 389 GB. Q4_K_S (470 GB) and Q8_0 (872 GB) fit no single machine in this index. The vision and audio encoders ship as separate files of 2–4 GB and are not included. Sizes come from the published GGUF files; Meta's benchmark claims are its own and no per-level quality loss has been published. The licence is not a standard open-source one: Meta's repository is gated, so downloads need an accepted access request; products built on it must show "Built with Muse Spark Open"; and a company with over $20M in annual revenue must sign a separate agreement with Meta before offering it as an API service.

Running Beam 1.0 501B-A23B locally

At Q8_0 and 4K of context, Beam 1.0 501B-A23B needs about 556.9 GB — 505.9 GB of weights, 0.31 GB of KV cache and a 50.6 GB activation buffer. No card in this index clears that comfortably at Q8_0, so at that level it is a multi-GPU or CPU-offload proposition. Its smaller Q2_K build needs about 190.9 GB, which the Mac M5 Ultra 512G clears comfortably. These are calculated figures, not measurements: the estimate stops counting a card as comfortable at 88% of its VRAM, which is roughly the room a desktop session needs.

What longer context costs

Going from 4K to 32K adds about 0.98 GB, taking the total to 558.0 GB. That is gentler than the parameter count suggests: only 9 of 52 layers keep a KV cache that grows with context, and 43 more cap theirs at a sliding window, so the cache scales at a fraction of the usual rate. The model's native window is 1M; holding all of it at Q8_0 would need about 596 GB.

Which build to download

This index only tracks Beam 1.0 501B-A23B in GGUF, across 2 levels (Q2_K, Q8_0). No per-level perplexity sweep has been published for this model, so the quality column is empty rather than estimated — within one model, more bits per weight is the only ordering the data supports. No throughput has been measured for this model on this site's hardware. GGUF runs on llama.cpp and Ollama across NVIDIA, AMD and Apple silicon; AWQ and GPTQ target vLLM on CUDA and ROCm; EXL2 is ExLlamaV2 — CUDA only, and now archived, so local use rather than serving.

Common questions

How much VRAM does Beam 1.0 501B-A23B need?
About 556.9 GB at Q8_0 with 4K of context and batch 1, rising to roughly 558.0 GB at 32K. That figure is weights plus KV cache plus a 10% activation buffer, calculated from the model's architecture rather than measured on a card.
Can Beam 1.0 501B-A23B run on a single GPU?
Not comfortably on any single card in this index at Q8_0. It needs about 556.9 GB, which means splitting across GPUs or offloading layers to system RAM. Its smaller Q2_K build needs about 190.9 GB, which the Mac M5 Ultra 512G clears comfortably.
Which quantization of Beam 1.0 501B-A23B should I use?
No published quality comparison exists for this model, so pick by footprint: Q2_K is the largest level here that fits a single machine in this index, and a higher bits-per-weight level is more faithful. All 2 levels in the index are Q2_K, Q8_0. Note this is a mixture-of-experts model — all parameters must be resident even though only a fraction are active per token, so the memory cost follows the total, not the active count.

Where this model fits

Sized at Q8_0 with a 4K context window, smallest card first. Comfortable means the estimate uses at most 88% of the memory.

Ships in
GGUF

This page's figures change when the model or the runtime does.Last updated 2026-10-18 RSS → /feed.xml