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Model ComparisonComparison10 min read

Flux 2 Dev vs Flux 1.1 Pro Ultra

Two generations of Flux meet: the open-weight Flux 2 Dev with its modern architecture versus Flux 1.1 Pro Ultra's native 4-megapixel output and raw mode photorealism. We analyze when resolution and raw aesthetics outweigh newer technology.

Background

New Architecture vs Premium Resolution

Black Forest Labs created these models for different purposes. Flux 2 Dev, released in January 2025, represents the company's latest architecture with open weights that researchers can study and customize. Flux 1.1 Pro Ultra, from the previous generation, focuses on a different value proposition: native 4-megapixel output and raw mode aesthetics designed for professional photography applications.

The cost difference is significant: Pro Ultra costs roughly 5× more than Flux 2 Dev for 1MP output. But the comparison isn't quite that simple—Pro Ultra includes 4 megapixels of native output resolution, so the per-megapixel premium is much smaller. When you need high-resolution output, the economics shift considerably.

Pro Ultra's "raw mode" deserves special attention. Enabled by default, it produces images with a more natural, less processed aesthetic—closer to what you'd expect from professional camera RAW files than typical AI generation. This makes Pro Ultra particularly compelling for stock photography, editorial work, and any application where authenticity matters more than the polished AI look.

Flux 2 Dev offers something Pro Ultra cannot: image-to-image generation. If your workflow involves transforming existing images, editing photos, or building on reference images, Flux 2 Dev is the only option here. Pro Ultra is purely text-to-image.

NoteFlux 2 Dev anchors the "quality/balanced" route for everyday quality needs. Flux 1.1 Pro Ultra appears in the "realistic/high" route when maximum photorealism and resolution are required.
Side by Side

Visual Comparison

Compare outputs from both models using identical prompts. Look for differences in resolution, natural aesthetics, and fine detail rendering.

PortraitProfessional portrait of a jazz musician, saxophone in hand, smoky club atmosphere, dramatic rim lighting, editorial photography quality
Flux 2 Devmodel=flux-2-dev
Flux 1.1 Pro Ultramodel=flux-1.1-pro-ultra
LandscapeDramatic Norwegian fjord at blue hour, mirror-still water reflecting snow-capped mountains, isolated cabin with warm lights, fine art landscape
Flux 2 Devmodel=flux-2-dev
Flux 1.1 Pro Ultramodel=flux-1.1-pro-ultra
ProductLuxury mechanical watch on dark slate, intricate movement visible through exhibition caseback, dramatic studio lighting, commercial photography
Flux 2 Devmodel=flux-2-dev
Flux 1.1 Pro Ultramodel=flux-1.1-pro-ultra
ArchitectureModern art museum interior, sweeping white concrete curves, natural light from skylights, visitors silhouetted, architectural photography
Flux 2 Devmodel=flux-2-dev
Flux 1.1 Pro Ultramodel=flux-1.1-pro-ultra
NatureMacro photograph of morning dew on a spider web, rainbow light refraction in droplets, shallow depth of field, nature photography
Flux 2 Devmodel=flux-2-dev
Flux 1.1 Pro Ultramodel=flux-1.1-pro-ultra

New to ImageGPT?

ImageGPT provides access to both Flux 2 Dev and Flux 1.1 Pro Ultra through a single API. Choose Dev for everyday generation with image-to-image support, or Pro Ultra when you need native 4MP output with professional photography aesthetics. Start with a 7-day free trial.

Sign up today for a 7-day free trial with 500 credits
Recommendations

When to Use Each Model

Choose based on your resolution needs, aesthetic preferences, and whether you require image-to-image capabilities.

recommended

Flux 2 Dev

  • Production workflows needing consistent quality
  • Image-to-image transformations and editing
  • Bulk content generation at reasonable cost
  • When 1MP resolution is sufficient
  • Iterating on concepts before final output
fits

Flux 1.1 Pro Ultra

  • Print materials requiring 4MP native resolution
  • Stock photography and editorial content
  • Professional photography simulation
  • Large-format displays and billboards
  • When raw mode aesthetics matter
Deep dive

Resolution & Fine Detail

Examining how 4MP versus 1MP impacts detail rendering when both models produce quality output.

Flux 2 Devmodel=flux-2-dev

Extreme close-up of a Bengal tiger's face, every whisker visible, intricate fur patterns, piercing amber eyes with refle…

Flux 1.1 Pro Ultramodel=flux-1.1-pro-ultra

Extreme close-up of a Bengal tiger's face, every whisker visible, intricate fur patterns, piercing amber eyes with refle…

Wildlife portraits demand extreme detail: individual whiskers, the complex banding patterns in tiger fur, and the layered reflections in feline eyes. These micro-details are where resolution differences become most apparent—and where Pro Ultra's 4MP output has an inherent advantage.

In our testing, Pro Ultra's native 4MP output revealed finer fur texture gradients and more precise whisker placement. Flux 2 Dev produced excellent quality that holds up well at normal viewing sizes, but when zoomed to 100%, Pro Ultra maintained detail that Dev approximated. For images destined for large prints or close examination, this resolution gap matters.

TipFor web use and social media, Flux 2 Dev's 1MP output is typically indistinguishable from Pro Ultra. Reserve Pro Ultra for print materials and large displays.
Deep dive

Raw Mode Aesthetics

Testing Pro Ultra's signature raw mode against Flux 2 Dev's standard processing.

Flux 2 Devmodel=flux-2-dev

Candid street photograph in Tokyo rain, neon reflections on wet pavement, passing pedestrians with umbrellas, documentar…

Flux 1.1 Pro Ultramodel=flux-1.1-pro-ultra

Candid street photograph in Tokyo rain, neon reflections on wet pavement, passing pedestrians with umbrellas, documentar…

This candid street scene tests photorealistic authenticity: natural lighting, atmospheric rain, realistic reflections, and the documentary feel of an unposed urban moment. It's exactly the kind of image where viewers subconsciously judge whether something looks "real" or "generated."

Pro Ultra's raw mode showed advantages in atmospheric rendering. Rain droplets, neon color falloff, and the overall tonal quality felt more natural and less processed. Flux 2 Dev produced a visually similar image but with slightly more saturated colors and a cleaner aesthetic that some might find appealing but others might identify as having that "AI look."

Deep dive

Portrait & Skin Rendering

Comparing how each model handles human subjects and natural skin tones.

Flux 2 Devmodel=flux-2-dev

Environmental portrait of a master calligrapher in her studio, natural window light, aged hands holding brush, contempla…

Flux 1.1 Pro Ultramodel=flux-1.1-pro-ultra

Environmental portrait of a master calligrapher in her studio, natural window light, aged hands holding brush, contempla…

Portraits are heavily scrutinized by human perception—we've evolved to read faces and hands with exceptional precision. This prompt demands realistic skin rendering across age ranges, the subtle textures of weathered hands, and convincing natural light interaction with human subjects.

Pro Ultra's raw mode produced more natural skin tones with subtle subsurface scattering effects. Aged skin texture and the delicate details of hands were rendered with particular care. Flux 2 Dev produced professional-quality portraits, but the skin sometimes appeared slightly more processed—still excellent, but less immediately "photographic" in that indefinable way.

NoteFor stock photography and editorial portraits where authentic aesthetics matter most, Pro Ultra's raw mode provides a distinct advantage.
Deep dive

Image-to-Image Capabilities

Exploring Flux 2 Dev's exclusive support for image input workflows.

Flux 2 Dev (supports img2img)model=flux-2-dev

Product photography of artisan leather bag, warm studio lighting, wooden surface, craftsman aesthetic, commercial photog…

Pro Ultra (text-to-image only)model=flux-1.1-pro-ultra

Product photography of artisan leather bag, warm studio lighting, wooden surface, craftsman aesthetic, commercial photog…

Flux 2 Dev supports image-to-image generation—a capability Pro Ultra lacks entirely. This enables workflows where you provide a reference image to guide generation: style transfer, image variations, product mockups from photos, and editing existing images with AI assistance.

For text-to-image generation, both models produce excellent product photography. But if your workflow involves transforming real product photos, creating variations from reference images, or any editing-based generation, Flux 2 Dev is your only choice. This functional difference may outweigh any quality or resolution considerations for many use cases.

TipIf image-to-image is essential to your workflow, Flux 2 Dev wins by default—Pro Ultra simply doesn't support it.
Deep dive

Cost-Efficiency Analysis

When does paying 5x more actually make sense?

Flux 2 Dev (~2.5s)model=flux-2-dev

Hero image for luxury hotel website, infinity pool overlooking tropical ocean, golden hour, travel photography, aspirati…

Pro Ultra (~8s, ~5× cost)model=flux-1.1-pro-ultra

Hero image for luxury hotel website, infinity pool overlooking tropical ocean, golden hour, travel photography, aspirati…

Consider the math: Pro Ultra costs about 5× more than Flux 2 Dev at 1MP resolution. If you're iterating on concepts, Dev lets you explore five variations for the price of one Pro Ultra output. For bulk content libraries, this cost difference compounds significantly.

Pro Ultra makes sense for specific scenarios: the hero image on your homepage that millions will see, the stock photography destined for print publications, the billboard creative that demands every pixel. For these high-stakes, high-visibility assets, the premium investment delivers native 4MP resolution and professional photography aesthetics that justify the cost.

NoteRecommended workflow: iterate with Flux 2 Dev to perfect your prompt, then generate the final version with Pro Ultra when you need maximum resolution and raw mode aesthetics.
Specifications

Feature Comparison

Technical specifications and capabilities for both models.

featureRelease
flux 2 devJanuary 2025
flux 1.1 pro ultra2024
featureArchitecture
flux 2 devFLUX.2 (open-weight)
flux 1.1 pro ultraFLUX.1.1 Pro (premium 4MP)
featureOutput resolution
flux 2 dev1MP standard
flux 1.1 pro ultra4MP (2048x2048+)
featureImage quality
flux 2 devExcellent
flux 1.1 pro ultraExcellent
featureFine details
flux 2 devVery Good
flux 1.1 pro ultraExceptional
featureGeneration speed
flux 2 dev~2.5s
flux 1.1 pro ultra~8s
featureRelative cost
flux 2 devBudget-friendly
flux 1.1 pro ultra~5× more expensive
featureText rendering
flux 2 devGood (6/10)
flux 1.1 pro ultraGood (7/10)
featurePrompt adherence
flux 2 devExcellent
flux 1.1 pro ultraExcellent
featureImage-to-image
flux 2 dev
flux 1.1 pro ultra—
featureRaw mode
flux 2 dev—
flux 1.1 pro ultra
featureELO score
flux 2 dev~1143
flux 1.1 pro ultraN/A (premium tier)
Try It Yourself

Try Flux 2 Dev

Try Flux 2 Dev with your own prompts. Generate images and compare results. Try portrait and landscape prompts to see how each model handles fine details and natural aesthetics.

Editorial fashion photograph in a sun-drenched Moroccan riad, in…

Frequently asked

Why would I choose a newer model over a higher-resolution one?Resolution isn't everything. Flux 2 Dev offers image-to-image capabilities that Pro Ultra lacks entirely. It's also faster (~2.5s vs ~8s), significantly cheaper for 1MP output, and represents more recent architectural improvements. For web use, social media, and workflows involving image editing, Dev is often the better choice despite Pro Ultra's resolution advantage.
What exactly is raw mode?Raw mode produces images with more natural, less processed aesthetics—similar to how professional photographers work with camera RAW files before processing. The result looks less 'AI-generated' and more like authentic photography. It's enabled by default on Pro Ultra and is particularly effective for portraits, landscapes, and editorial content where that authentic look matters.
When does 4MP resolution actually matter?4MP (roughly 2048x2048) matters for print media at 300 DPI (about 6.8 inches square), large digital displays, and any use case where viewers examine fine details. For web thumbnails, social media, and most digital applications, 1MP is sufficient. The resolution question is really about your output medium, not the model's capabilities.
Can I use Flux 2 Dev for image editing workflows?Yes, Flux 2 Dev supports image-to-image generation, which enables workflows like style transfer, image variations, and guided editing based on reference images. Pro Ultra does not support this—it's text-to-image only. If image input is part of your workflow, Flux 2 Dev is your only option between these two.
Which model is better for professional photography?It depends on the specific use case. Pro Ultra excels at simulating professional photography aesthetics with its raw mode and high resolution—ideal for stock photography and editorial content. Flux 2 Dev produces excellent quality that's often indistinguishable at web sizes, at a fraction of the cost. For final assets that need print resolution and authentic aesthetics, Pro Ultra; for everything else, Dev.
How do the generation speeds compare?Flux 2 Dev generates in approximately 2.5 seconds, while Pro Ultra takes about 8 seconds—over 3x longer. This difference compounds in batch workflows. If you're iterating on concepts, Dev's speed advantage lets you explore more variations in less time before committing to a final output.

Resolution or flexibility?
Choose what fits your workflow.

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