FLUX1.1 Pro Ultra: High-Resolution Images and Raw Mode Guide

FLUX1.1 [pro] Ultra is Black Forest Labs’ hosted image generator for creating images from text at up to four megapixels. You access it through the BFL API or supported providers; Ultra has no released open weights for local inference. Its optional Raw mode targets the appearance of candid photography. BFL product page, Ultra documentation

This guide covers Ultra’s output modes, API request submission, and the steps for retrieving a finished image. The useful decision is whether you need a finished image with more pixels, a photographic aesthetic, or a model whose weights you can run yourself.

What are the key facts about FLUX1.1 Pro Ultra?

What can FLUX1.1 Pro Ultra and Raw mode do?

Ultra provides a documented route to higher-resolution generation within the FLUX1.1 family. BFL introduced it as a fourfold resolution increase over standard FLUX1.1 [pro], with an upper output size of four megapixels. That describes pixel area; it should not be read as a promise of a particular “4K” width and height. Launch announcement

Raw mode is an aesthetic control. BFL describes it as producing a less synthetic photographic appearance, including candid human subjects and nature scenes. Use that description as a reason to compare samples for your own brief, rather than as proof that every Raw image will look more convincing. Ultra documentation

Image guidance is another useful control: the API accepts a reference image and an influence setting. This supports experiments in which a visual reference helps establish the intended appearance, while the prompt describes the scene. Ultra documentation

For a practical evaluation, choose a subject whose details you can inspect: a jacket with seams, a ceramic cup on a table, or a shopfront with clear perspective. Compare the image at its intended display size and at full resolution. More pixels are useful only when the details serve the final composition.

What are FLUX1.1 Pro Ultra's limits?

Ultra’s hosted delivery means you cannot download its weights and replace the service with a local GPU. BFL’s downloadable FLUX.1-dev and FLUX.1-schnell models are separate choices with their own access terms. A locally installed interface does not change where an API model executes. FLUX access overview

Raw mode also does not mean a camera RAW file. The API documents JPEG and PNG as output formats, while raw is a generation setting. Choose the export format separately from the visual style. API reference

BFL published generation timing in the launch announcement, but that is a vendor measurement rather than a guaranteed completion time for your application. Budget for request submission, processing, result retrieval, and any retries you deliberately implement. Launch announcement, API quickstart

Image guidance should not be treated as a promise of exact object preservation. If your brief requires unchanged lettering, geometry, or a precise product silhouette, make those explicit review criteria. Keep the original reference beside the generated output during approval.

How do you use FLUX1.1 Pro Ultra through the API?

Create a BFL account, obtain an API key, and configure it as BFL_API_KEY in your server environment. The documented request header is x-key; the Ultra endpoint is /v1/flux-pro-1.1-ultra. API quickstart, API reference

The following submission example uses Python with the requests package installed. The prompt and aspect ratio are illustrative choices, and raw selects the photographic mode:

import os
import requests

response = requests.post(
    "https://api.bfl.ai/v1/flux-pro-1.1-ultra",
    headers={"x-key": os.environ["BFL_API_KEY"]},
    json={
        "prompt": "Candid photograph of a florist arranging stems beside a window",
        "aspect_ratio": "4:3",
        "raw": True,
    },
    timeout=60,
)
response.raise_for_status()
job = response.json()
print(job["polling_url"])

This prints a job polling URL, not the image. Poll the returned URL using the documented result procedure; when the status is Ready, retrieve the image URL from result.sample. Handle unsuccessful terminal states as failures instead of continuing to poll indefinitely. API quickstart

Download the completed image promptly. BFL documents a limited lifetime for signed result URLs, so store the image itself if your application needs durable access. Save the prompt, model endpoint, output mode, and request identifier alongside it. Ultra documentation

For a comparison session, keep the scene description and aspect ratio unchanged, then compare Raw enabled and disabled. Review the entire set before choosing a favorite. This is a suggested evaluation process; it does not establish a measured advantage for either mode.

ComfyUI also documents an Ultra partner-node workflow. That is an API integration requiring the relevant service access, rather than a downloadable Ultra checkpoint. ComfyUI’s official example

How does Ultra compare with downloadable FLUX models?

These differences concern access and workflow, not a universal quality ranking. For composition and lighting practice, read Realistic Photos with FLUX. For the related access question, see FLUX Ultra access options.

What else should you know about FLUX1.1 Pro Ultra?

Can FLUX1.1 Pro Ultra run locally?

FLUX1.1 Pro Ultra is accessed through hosted services and has no released open weights. FLUX.1-dev and FLUX.1-schnell provide separate downloadable options for supported local workflows. BFL product page, Dev card, Schnell card

Does Ultra Raw mode export a RAW photograph?

FLUX1.1 Pro Ultra's raw setting changes the generated aesthetic. Its output_format parameter independently selects JPEG or PNG. Ultra API documentation

Is FLUX1.1 Pro Ultra free to use?

FLUX1.1 Pro Ultra uses paid API access, with the rate listed in BFL's model documentation. Check the current rate for your chosen provider before submitting requests. Ultra documentation

Can I guide FLUX1.1 Pro Ultra with an existing image?

FLUX1.1 Pro Ultra accepts image_prompt and image_prompt_strength for reference-image guidance. Inspect the output against the reference for details your project needs to retain. Ultra API documentation

Sources

• BFL Ultra product page
• Ultra and Raw launch announcement
• Ultra model documentation
• BFL image-generation quickstart
• Original FLUX family announcement
• ComfyUI Ultra partner-node documentation
• FLUX.1-dev model card
• FLUX.1-schnell model card

Related guides on PromptZone

• Realistic Photos with FLUX
• Best SDXL Models in 2026