MolmoAct2 is an open vision-language-action model for robot control. It builds on Molmo2-ER, an embodied-reasoning VLM backbone, and connects the autoregressive VLM to a flow-matching continuous action expert through per-layer KV (key-value) conditioning. This checkpoint is the post-trained, multi-embodiment MolmoAct2 model. It is intended as a foundation checkpoint for further robot fine-tuning rather than as a ready-to-run policy for a single deployment setting. Use this checkpoint for further fine-tuning on a target robot embodiment or benchmark. It contains the VLM and continuous action expert weights, plus normalization metadata for the post-training mixture in normstats.json. This…
Open-weight model · Robotics
molmoact2_busybox_push_green_button_b0_fft
by Fanqi Robo fanqi-robo/molmoact2_busybox_push_green_button_b0_fft
molmoact2_busybox_push_green_button_b0_fft is an open-weight model for robotics from Fanqi Robo. It has 5.4B parameters. At 16-bit it needs about 13.1 GB of GPU memory, which fits on 1x MI300X from $1.85 an hour, at the lowest prices in the SAVRN Index.
Arm b0fft (group baseline) of the MolmoAct2 baseline pair in experimental/lerobotpolicymolmoact2/modal/ (alpha-robotics, branch policytestfanqi), run with the same protocol as the π0.5 grid in experimental/lerobotpolicypi05/.
Parameters5.4B
Context—
Weights10.9 GB
License—
AccessOpen weights
Monthly Downloads—
Runs On
What it takes to serve molmoact2_busybox_push_green_button_b0_fft (5.4B parameters): the memory its weights need at each precision, and the cheapest way to rent enough data-center GPUs to hold them.
| Precision | Weights | Memory needed | Cheapest setup | Per hour | Also fits |
|---|---|---|---|---|---|
| 16-bit | 10.9 GB | 13.1 GB | 1x MI300X (192 GB) Vultr |
$1.85 | 1x H100 $1.99 · 1x MI325X $2.00 |
| 8-bit | 5.4 GB | 6.5 GB | 1x MI300X (192 GB) Vultr |
$1.85 | 1x H100 $1.99 · 1x MI325X $2.00 |
| 4-bit | 2.7 GB | 3.3 GB | 1x MI300X (192 GB) Vultr |
$1.85 | 1x H100 $1.99 · 1x MI325X $2.00 |
Memory is the weights at that precision plus 20% for the runtime and a short context; a long context needs more. Prices are the lowest on-demand hourly rates in the SAVRN Index, read Oct 18, 2026.
Model Card
Arm b0fft (group baseline) of the MolmoAct2 baseline pair in experimental/lerobotpolicymolmoact2/modal/ (alpha-robotics, branch policytestfanqi), run with the same protocol as the π0.5 grid in experimental/lerobotpolicypi05/. The only test is the real robot: submit fanqi-robo/molmoact2busyboxpushgreenbuttonb0fft (or a step repo) on https://huggingface.co/spaces/armnet/armnet-eval (embodiment lerobot/so-101, task pushgreenbutton, 20 rollouts, variation seed 42). Native horizon: execute the full 30-step chunk (nactionsteps=30).
Excerpt from the card by Fanqi Robo.
Identity and Version
- Repository
- fanqi-robo/molmoact2_busybox_push_green_button_b0_fft
- Publisher
- Fanqi Robo
- Task
- Robotics
- Modality
- Control
- Library
- lerobot
- Parameters
- 5.4B parameters
- Languages
- Not stated by the source
- Revision
- 30a804309cee4ed0ce2ec72ebd9dc21b3cd771bc
- First published
- 2026-09-29
- Last updated
- 2026-09-29
Files and Weights
10 files, 10.9 GB in total. The weights are 3 files totalling 10.9 GB in safetensors.
Weights3 files · 10.9 GB
Configuration5 files · 17.4 KB
Documentation1 file · 4.5 KB
Repository1 file · 1.5 KB
Every file
| File | Type | Size | SHA-256 |
|---|---|---|---|
| model.safetensors | Weights | 10.9 GB | 9dce09d2e707 |
| policy_postprocessor_step_1_molmoact2_masked_unnormalizer.safetensors | Weights | 8.7 KB | 820a6f1818a3 |
| policy_preprocessor_step_2_molmoact2_masked_normalizer.safetensors | Weights | 8.7 KB | 9081692fb398 |
| MANIFEST.json | Configuration | 1.4 KB | — |
| config.json | Configuration | 3.9 KB | — |
| policy_postprocessor.json | Configuration | 757 B | — |
| policy_preprocessor.json | Configuration | 2.5 KB | — |
| train_config.json | Configuration | 8.9 KB | — |
| README.md | Documentation | 4.5 KB | — |
| .gitattributes | Repository | 1.5 KB | — |
License and Download
- License
- Not stated by the source
- Access
- Open weights, no gate
- Download size
- 10.9 GB
Download from Fanqi Robo
Released by Fanqi Robo through its official repository on Hugging Face.
Built From
- Derived from allenai/MolmoAct2
- Trained on (disclosed) fanqi-robo/busybox_push_green_button
Memory Requirements
| Precision | Weights in memory |
|---|---|
| As published | 10.9 GB |
| 16-bit | 10.9 GB |
| 8-bit | 5.4 GB |
| 4-bit | 2.7 GB |
Weights only, from the published parameter count; the key-value cache and runtime add to this.
Questions About molmoact2_busybox_push_green_button_b0_fft
How much GPU memory does molmoact2_busybox_push_green_button_b0_fft need?
About 13.1 GB at 16-bit and 3.3 GB at 4-bit: the weights (5.4B parameters) plus a working margin. A long context needs more.
What is the cheapest GPU to run molmoact2_busybox_push_green_button_b0_fft on?
At 16-bit, 1x MI300X from $1.85 an hour; at 4-bit, 1x MI300X from $1.85 an hour, at the lowest on-demand prices the SAVRN Index lists.
Similar Models
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