Model Comparison

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.

Comparison10 min read
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.

Note: Flux 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.

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

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.

Recommendations

When to Use Each Model

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

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

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 Dev
"Extreme close-up of a Bengal tiger's face, every whisker vis..."
Flux 2 Dev result
Model: flux-2-dev
Extreme close-up of a Bengal tiger's face, every whisker visible, intricate fur patterns, piercing amber eyes with reflections, wildlife photography, National Geographic cover quality
Flux 1.1 Pro Ultra
"Extreme close-up of a Bengal tiger's face, every whisker vis..."
Flux 1.1 Pro Ultra result
Model: flux-1.1-pro-ultra
Extreme close-up of a Bengal tiger's face, every whisker visible, intricate fur patterns, piercing amber eyes with reflections, wildlife photography, National Geographic cover quality

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.

Tip: For 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 Dev
"Candid street photograph in Tokyo rain, neon reflections on ..."
Flux 2 Dev result
Model: flux-2-dev
Candid street photograph in Tokyo rain, neon reflections on wet pavement, passing pedestrians with umbrellas, documentary style, authentic urban atmosphere
Flux 1.1 Pro Ultra
"Candid street photograph in Tokyo rain, neon reflections on ..."
Flux 1.1 Pro Ultra result
Model: flux-1.1-pro-ultra
Candid street photograph in Tokyo rain, neon reflections on wet pavement, passing pedestrians with umbrellas, documentary style, authentic urban atmosphere

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 Dev
"Environmental portrait of a master calligrapher in her studi..."
Flux 2 Dev result
Model: flux-2-dev
Environmental portrait of a master calligrapher in her studio, natural window light, aged hands holding brush, contemplative expression, documentary photography style
Flux 1.1 Pro Ultra
"Environmental portrait of a master calligrapher in her studi..."
Flux 1.1 Pro Ultra result
Model: flux-1.1-pro-ultra
Environmental portrait of a master calligrapher in her studio, natural window light, aged hands holding brush, contemplative expression, documentary photography style

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.

Note: For 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)
"Product photography of artisan leather bag, warm studio ligh..."
Flux 2 Dev (supports img2img) result
Model: flux-2-dev
Product photography of artisan leather bag, warm studio lighting, wooden surface, craftsman aesthetic, commercial photography
Pro Ultra (text-to-image only)
"Product photography of artisan leather bag, warm studio ligh..."
Pro Ultra (text-to-image only) result
Model: flux-1.1-pro-ultra
Product photography of artisan leather bag, warm studio lighting, wooden surface, craftsman aesthetic, commercial photography

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.

Tip: If 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)
"Hero image for luxury hotel website, infinity pool overlooki..."
Flux 2 Dev (~2.5s) result
Model: flux-2-dev
Hero image for luxury hotel website, infinity pool overlooking tropical ocean, golden hour, travel photography, aspirational lifestyle
Pro Ultra (~8s, ~5× cost)
"Hero image for luxury hotel website, infinity pool overlooki..."
Pro Ultra (~8s, ~5× cost) result
Model: flux-1.1-pro-ultra
Hero image for luxury hotel website, infinity pool overlooking tropical ocean, golden hour, travel photography, aspirational lifestyle

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.

Note: Recommended 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.

FeatureFlux 2 DevFlux 1.1 Pro Ultra
ReleaseJanuary 20252024
ArchitectureFLUX.2 (open-weight)FLUX.1.1 Pro (premium 4MP)
Output resolution1MP standard4MP (2048x2048+)
Image qualityExcellentExcellent
Fine detailsVery GoodExceptional
Generation speed~2.5s~8s
Relative costBudget-friendly~5× more expensive
Text renderingGood (6/10)Good (7/10)
Prompt adherenceExcellentExcellent
Image-to-image
Raw mode
ELO score~1143N/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.

Generated visual
https://demo.imagegpt.host/image?prompt=Editorial+fashion+photograph+in+a+sun-drenched+Moroccan+riad%2C+intricate+tilework%2C+golden+hour+light+through+archways%2C+flowing+silk+fabric%2C+Vogue+quality&model=flux-2-dev

Frequently Asked Questions

Resolution or flexibility?
Choose what fits your workflow.