FLAN-T5-XXL (Text-Encoder Only)

• Guide (External Site): English | Japanese

• Why Use FP32 Text Encoder? (External Site): English | Japanese

• Hugging Face

The FP8 and GGUF format is distributed as a compressed ZIP file. Please unzip it using any decompression software of your choice before use, or download from Hugging Face page.

FLAN-T5-XXL is a fine-tuned version of T5-XXL v1.1, designed to improve accuracy and performance.

The original FLAN-T5-XXL model is available on Google's Hugging Face page.

When used with Flux.1, SD3.5 and HiDream, replacement for T5-XXL v1.1 to FLAN-T5-XXL offers improved prompt comprehension and enhanced image quality.

This model has been streamlined by extracting only the text encoder portion, making it optimized for image generation workflows.

Model Variants

FP32

Full precision, highest quality — largest file size and heaviest VRAM/compute footprint. Best for archival or when maximum fidelity matters more than speed.

FP16

Half precision with virtually no perceptible quality loss for most use cases. The recommended default — a solid balance of accuracy and file size.

INT8_ConvRot_HQ

Lightweight 8-bit quantization using rotation-based conversion, preserving unusually high accuracy despite the reduced size. Great if you want INT8-level savings without the usual quality trade-off.

MXFP8 / FP8_svd_scaled / FP8

⚠️ Currently not recommended. These FP8 variants are kept for compatibility/testing but show degraded quality or stability compared to the other options — use INT8_ConvRot_HQ instead.

GGUF (Q8_0 / Q6_K / Q5_K_M / Q4_K_M)

Excellent compression ratios for constrained environments. Quality scales down the quantization ladder (Q8_0 closest to full precision, Q4_K_M smallest but with more quality loss) — pick based on your available memory.

Comparisons

• FLAN-T5-XXL vs T5-XXL v1.1

• FLAN-T5-XXL FP32 vs FP16 and Quantization

• INT8_ConvRot vs FP8 (Other Model)

Tip: Upgrade CLIP-L Too

For even better results, consider pairing FLAN-T5-XXL with an upgraded CLIP-L text encoder:

• LongCLIP-SAE-ViT-L-14 (ComfyUI only)

• CLIP-SAE-ViT-L-14

Combining FLAN-T5-XXL with an enhanced CLIP-L model can further boost image quality.

License

• Apache 2.0

This model is based on Google's FLAN-T5-XXL, also licensed under Apache 2.0.

Update History

2026.7.10

• Upload INT8_ConvRot_HQ

2025.6.24

• Re-upload of the GGUF model, reduction in model size, and correction of metadata.