black-forest-labs · image

FLUX.2-klein-4B

black-forest-labs/FLUX.2-klein-4B

FLUX.2-klein-4B at Q4_K_M is exactly 2,497,280,416 bytes (2.33 GiB / 2.50 GB) — an effective 5.155 bits per weight, not the nominal 4.

From the file· summed from 1 file(s)
Parameters
3.9B
Architecture
flux
Context
native (config.json)
License
apache-2.0

Shipped quantizations

exact bytes, summed from published files
QuantSizeExact bytesEffective bpwTensorsPublisher
Q2_K1.70 GiB1,827,807,8083.773unsloth
Q3_K_S1.96 GiB2,101,928,5124.339unsloth
Q3_K_M1.98 GiB2,124,489,2804.385149unsloth
Q4_02.29 GiB2,460,378,5605.079149leejet
Q4_02.29 GiB2,460,394,0485.079149unsloth
Q4_K_M2.33 GiB2,497,280,4165.155ponpoke
Q4_K_S2.41 GiB2,583,077,4405.332unsloth
Q4_K_M2.43 GiB2,604,311,1045.376149unsloth
Q4_12.51 GiB2,690,425,4085.554unsloth
Q5_02.72 GiB2,920,456,7686.029unsloth
Q5_K_S2.84 GiB3,050,807,8726.298unsloth
Q5_K_M2.86 GiB3,073,368,6406.344149unsloth
Q5_12.93 GiB3,150,488,1286.503unsloth
Q6_K3.08 GiB3,306,260,8966.825ponpoke
Q6_K3.18 GiB3,409,273,4087.037149unsloth
Q8_03.99 GiB4,280,404,8968.836ponpoke
Q8_04.01 GiB4,300,629,4408.877149leejet
Q8_04.01 GiB4,300,644,9288.877149unsloth
BF167.22 GiB7,751,115,32816.000unsloth
F167.22 GiB7,751,115,32816.000149unsloth
F167.50 GiB8,051,284,89616.620ponpoke

Pipeline components

a diffusion model is a graph of parts, not one file
ComponentSizeShareCan live on the CPU?
text encoder7.49 GiB50%yes — the usual first VRAM saving
denoiser7.22 GiB49%no, must be resident
vae0.16 GiB1%no, must be resident
Full pipeline14.87 GiBresident if nothing is offloaded

The parameter count published for a diffusion model describes the denoiser alone. Running it also requires its text encoder and VAE, and the text encoder is often nearly as large as the denoiser — which is why offloading it is the standard first move when you run out of memory. This repository also ships a single-file copy of the denoiser at its root; we count it once, not twice.

We publish component sizes here, not throughput. Community-submitted image-generation rates do exist for many GPUs and we show them on the hardware pages, but they aggregate runs at different resolutions, step counts and settings, so they cannot be attributed to one model. Peak memory during sampling is unmeasured by any public source, and we do not estimate it.

Compare with

same modality, comparable size

Will it run on your card?

full quant x context sweep

Why other calculators give a different number

A parameters × bits ÷ 8 estimate puts Q4_K_M at roughly 2.03 GiB. The real file is 2.33 GiB, because a quantization is a mixture and some tensors are always kept at higher precision.

Architecture

Architecture unavailable — this repository is gated and no ungated mirror was found. Exact file sizes above are still authoritative; only the KV math needs the config.

Questions people ask

How much VRAM does FLUX.2-klein-4B need?
Q4_K_M is exactly 2,497,280,416 bytes (2.33 GiB) in weights. Add the KV cache, which depends on your context length, plus roughly half a gigabyte of runtime overhead.
Which quantization of FLUX.2-klein-4B should I use?
Q4_K_M is the usual default. Pick the largest quantization that fits your card at the context you actually need — the table above gives exact sizes for every one published.