FLUX.2-klein-4B
black-forest-labs/FLUX.2-klein-4B
Official · BF16 · safetensors
Runtime certified: Diffusers
| Precision / quantization | Format | Bits | Publisher trust | Deployment state |
|---|---|---|---|---|
| BF16 | safetensors | 16 | Official | Runtime certified |
FLUX · General · FLUX.2
FLUX.2 Klein 4B: Specs, GPU requirements, hosting & deployment
FLUX.2 Klein 4B is a current Image Generation release in the FLUX family, certified from its immutable official source revision.
Total parameters3.9B
Active parametersN/A / Not directly comparable
Context windowN/A / Not directly comparable
Release statusCurrent · Current
ArchitectureRectified-flow transformer
ModalitiesImage
Licenseapache-2.0
Deployment stateDeployable with certified configuration
Commercial stateCommercial Use Allowed
Release date2026-01-14
Architecture, strengths and use cases
FLUX.2 Klein 4B is an official self-hostable Black Forest Labs Image generation release. It uses Rectified-flow transformer with 3.875B. Exact checkpoint, license, runtime, and hardware evidence is tied to the verified upstream revision.
FLUX.2 Klein 4B uses Rectified-flow transformer with 3.875B. Pipeline and configuration fields are reported only where the official source publishes them.
Verified Rectified-flow transformer architecture
Official checkpoint and pipeline evidence
Official BF16, Unknown checkpoint coverage
Self-hosted Image generation workloads
Controlled model evaluation
Production deployment planning
Certified checkpoints and quantizations
Only exact, source-certified variants attached to this release are shown.
Recommended hardware
Use only the listed runtime configurations with the exact checkpoint precision. Hardware sizing considers resident pipeline memory, runtime overhead, input and output dimensions, batch size, and safety headroom.
Estimated weight memory7.43 GB
Runtime overhead10.78 GB
Total with safety margin22.58 GB
Recommended best value
1× NVIDIA A100 SXM 80GB
80 GB total VRAM · nvlink
57.42 GB headroom · Available
$915.00 / monthLowest-cost viable
1× NVIDIA L4 24GB
24 GB total VRAM · pcie
1.42 GB headroom · Available
$250.00 / monthHighest performance
1× NVIDIA H200 SXM 141GB
141 GB total VRAM · nvswitch
118.42 GB headroom · Limited capacity
$2,345.00 / monthLicense and self-hosting considerations
The exact pipeline and selected precision must fit on the chosen GPUs. Requirements vary with resolution, duration, batch size, modalities, and runtime; language-model KV-cache rules are not applied.
FLUX.2 Klein 4B is published under apache-2.0. The release-scoped official license link and verification date are retained with the catalogue record.
Commercial Use Allowed. The official license permits commercial use; its obligations still apply.
Alternatives and sibling variants
FLUX.2 Klein 9B, FLUX.2-dev, FLUX.2-klein-9B
Release timeline
black-forest-labs/flux/flux-2-klein-4b @ 4f9ba59dd8f5f6752667d54a9f93a2c379fcd9ce26069cc481fdaca7a833343f
Frequently asked questions
How much VRAM does FLUX.2 Klein 4B require?
The estimate uses the certified checkpoint, precision, runtime, workload dimensions, batch size, and domain-specific overhead.
Which runtimes support FLUX.2 Klein 4B?
Certified upstream runtime evidence is available for diffusers.
Can FLUX.2 Klein 4B be used commercially?
The stored commercial classification is Commercial Use Allowed. Consult the official apache-2.0 terms for the final obligations.
Official references
Last verified: 2026-09-03