Model Comparison

Flux 1 Schnell vs Flux 2 Dev

Comparing two generations of Flux models: the ultra-fast Flux 1 Schnell against the higher-quality Flux 2 Dev. We analyze when speed matters more than detail, and when it's worth waiting for better results.

Comparison8 min read
Background

Two Generations of Flux

Black Forest Labs is the team behind Stable Diffusion—and when some of that team split off to build something new, they created the Flux model family. Flux 1 Schnell ("schnell" is German for "fast") launched in 2024 as the speed-focused option. Flux 2 Dev followed in January 2025 with an upgraded architecture that trades speed for quality.

These two models represent a fundamental trade-off in AI image generation: how much quality are you willing to sacrifice for faster results? Flux 1 Schnell generates images in roughly one second, making it practical for real-time applications and rapid iteration. Flux 2 Dev takes about 2-3 seconds but produces noticeably better detail, prompt adherence, and overall coherence.

The cost difference reflects this gap. Flux 2 Dev is roughly 3-4× more expensive than Schnell for typical image sizes. For high-volume workflows, that difference adds up quickly.

One significant feature difference: Flux 2 Dev supports image-to-image generation, letting you use a source image as a starting point for modifications. Flux 1 Schnell is text-to-image only—if you need to iterate on an existing image, you'll need to use a different model.

Note: Both models are available through ImageGPT's quality routes. Flux 1 Schnell appears in "quality/fast" routes, while Flux 2 Dev is the backbone of "quality/balanced" routes.

Side by Side

Visual Comparison

Compare outputs from both models using identical prompts. Notice how Flux 2 Dev tends to produce more refined details.

PromptFlux 1 SchnellFlux 2 Dev
PortraitClose-up portrait of an elderly fisherman with weathered skin, deep wrinkles, piercing blue eyes, natural lighting
Flux 1 Schnell - Portrait
Model: flux-1-schnell
Close-up portrait of an elderly fisherman with weathered skin, deep wrinkles, piercing blue eyes, natural lighting
Flux 2 Dev - Portrait
Model: flux-2-dev
Close-up portrait of an elderly fisherman with weathered skin, deep wrinkles, piercing blue eyes, natural lighting
LandscapeDramatic mountain valley at sunset, snow-capped peaks, winding river, volumetric fog, cinematic composition
Flux 1 Schnell - Landscape
Model: flux-1-schnell
Dramatic mountain valley at sunset, snow-capped peaks, winding river, volumetric fog, cinematic composition
Flux 2 Dev - Landscape
Model: flux-2-dev
Dramatic mountain valley at sunset, snow-capped peaks, winding river, volumetric fog, cinematic composition
TextA rustic wooden sign that says "FRESH BREAD" hanging outside a French bakery, morning light
Flux 1 Schnell - Text
Model: flux-1-schnell
A rustic wooden sign that says "FRESH BREAD" hanging outside a French bakery, morning light
Flux 2 Dev - Text
Model: flux-2-dev
A rustic wooden sign that says "FRESH BREAD" hanging outside a French bakery, morning light
ProductLuxury perfume bottle on a marble surface, dramatic studio lighting, reflection, minimalist composition, 4K product photography
Flux 1 Schnell - Product
Model: flux-1-schnell
Luxury perfume bottle on a marble surface, dramatic studio lighting, reflection, minimalist composition, 4K product photography
Flux 2 Dev - Product
Model: flux-2-dev
Luxury perfume bottle on a marble surface, dramatic studio lighting, reflection, minimalist composition, 4K product photography
ArchitectureModern minimalist house with floor-to-ceiling windows, surrounded by forest, golden hour, architectural photography
Flux 1 Schnell - Architecture
Model: flux-1-schnell
Modern minimalist house with floor-to-ceiling windows, surrounded by forest, golden hour, architectural photography
Flux 2 Dev - Architecture
Model: flux-2-dev
Modern minimalist house with floor-to-ceiling windows, surrounded by forest, golden hour, architectural photography

New to ImageGPT?

ImageGPT is the easiest way to add custom images to your site, app, or agent. Access both Flux 1 Schnell and Flux 2 Dev through a single img tag—no need to manage different providers or API keys. Start with a 7-day free trial.

Recommendations

When to Use Each Model

Each model excels in different scenarios. Choose based on your priorities for speed, quality, and budget.

Flux 1 Schnell

  • Real-time applications needing sub-second response
  • Rapid prompt iteration and experimentation
  • High-volume batch processing on a budget
  • Thumbnails and preview images
  • When good-enough quality is acceptable

Flux 2 Dev

  • Final production assets
  • Detail-rich images (portraits, products)
  • Image-to-image workflows
  • When prompt accuracy matters
  • Professional and commercial use
Deep Dive

Fine Detail & Texture

Comparing how each model handles intricate details like skin texture, fabric weave, and surface materials.

Flux 1 Schnell
"Extreme close-up of a honeybee on a sunflower, showing indiv..."
Flux 1 Schnell result
Model: flux-1-schnell
Extreme close-up of a honeybee on a sunflower, showing individual pollen grains on fuzzy legs, compound eye detail, macro photography, natural lighting
Flux 2 Dev
"Extreme close-up of a honeybee on a sunflower, showing indiv..."
Flux 2 Dev result
Model: flux-2-dev
Extreme close-up of a honeybee on a sunflower, showing individual pollen grains on fuzzy legs, compound eye detail, macro photography, natural lighting

Fine detail is where the generation gap between these models becomes most apparent. This macro photography prompt demands precise rendering of tiny elements: individual pollen grains, the compound eye's facets, and the fine hairs on the bee's body.

In our testing, Flux 2 Dev tended to produce more defined textures and maintain sharpness across the image. Flux 1 Schnell often delivered acceptable results at first glance, but closer inspection revealed softer details and less distinct separations between fine elements. The difference matters most when images will be viewed at larger sizes or printed.

Tip: For thumbnails or small display sizes, Schnell's softer details may be perfectly acceptable—and significantly cheaper.

Deep Dive

Prompt Adherence

Testing how faithfully each model interprets complex, multi-element prompts.

Flux 1 Schnell
"A red vintage Vespa scooter parked outside a yellow door, co..."
Flux 1 Schnell result
Model: flux-1-schnell
A red vintage Vespa scooter parked outside a yellow door, cobblestone street, potted olive tree to the left, string lights overhead, Mediterranean summer afternoon
Flux 2 Dev
"A red vintage Vespa scooter parked outside a yellow door, co..."
Flux 2 Dev result
Model: flux-2-dev
A red vintage Vespa scooter parked outside a yellow door, cobblestone street, potted olive tree to the left, string lights overhead, Mediterranean summer afternoon

This prompt includes specific elements with defined positions: a red Vespa, a yellow door, an olive tree on the left, and string lights above. Models that struggle with prompt adherence might change colors, omit elements, or misplace objects.

Flux 2 Dev's higher ELO score (~1143 vs ~1050) reflects better prompt understanding overall. In practice, we observed that Flux 2 Dev more consistently included all specified elements and positioned them correctly. Schnell sometimes omitted minor details or interpreted spatial relationships differently. For prompts where specific elements matter, the newer model tends to be more reliable.

Note: Complex prompts with many specific requirements benefit most from Flux 2 Dev's improved comprehension.

Deep Dive

Text Rendering Accuracy

Evaluating how accurately each model renders legible text without errors or distortion.

Flux 1 Schnell
"A neon sign in a bar window that reads "COLD BEER" in glowin..."
Flux 1 Schnell result
Model: flux-1-schnell
A neon sign in a bar window that reads "COLD BEER" in glowing blue letters, rainy night, reflections on wet pavement, urban atmosphere
Flux 2 Dev
"A neon sign in a bar window that reads "COLD BEER" in glowin..."
Flux 2 Dev result
Model: flux-2-dev
A neon sign in a bar window that reads "COLD BEER" in glowing blue letters, rainy night, reflections on wet pavement, urban atmosphere

Text rendering remains challenging for image generation models. Common failures include misspelled words, distorted characters, and illegible letterforms. This prompt tests a simple two-word phrase in a stylized neon context.

Neither model excels at text—both are rated "Basic" to "Good" compared to specialized text-rendering models like Ideogram V3. However, Flux 2 Dev showed more consistency in our testing, producing readable results more often. Schnell's speed comes at the cost of text accuracy. For images where text must be perfect, consider using a text-specialized route instead.

Warning: Always verify generated text carefully. For critical text rendering, consider using the text/high route with Ideogram V3 or Recraft V3.

Deep Dive

Lighting & Atmosphere

Comparing how each model interprets complex lighting scenarios and mood.

Flux 1 Schnell
"Cozy reading nook by a window during a thunderstorm, warm la..."
Flux 1 Schnell result
Model: flux-1-schnell
Cozy reading nook by a window during a thunderstorm, warm lamp light contrasting with blue-gray stormy sky, rain streaks on glass, comfortable armchair with throw blanket
Flux 2 Dev
"Cozy reading nook by a window during a thunderstorm, warm la..."
Flux 2 Dev result
Model: flux-2-dev
Cozy reading nook by a window during a thunderstorm, warm lamp light contrasting with blue-gray stormy sky, rain streaks on glass, comfortable armchair with throw blanket

This prompt requires understanding of multiple light sources (warm lamp, cool storm light), weather effects (rain on glass), and overall atmospheric mood. The contrast between cozy interior and dramatic exterior is key to the image's emotional impact.

Flux 2 Dev's additional processing time allows it to render more nuanced lighting interactions—the way warm lamplight plays against rain-streaked glass, subtle color gradients in the stormy sky. Schnell often captured the basic concept but with flatter lighting and less atmospheric depth. For images where mood matters, the quality difference becomes more significant.

Deep Dive

The Speed-Quality Trade-off

When does faster generation matter more than higher quality?

Schnell (~1s)
"Professional headshot of a business executive, studio lighti..."
Schnell (~1s) result
Model: flux-1-schnell
Professional headshot of a business executive, studio lighting, neutral background, corporate portrait
Flux 2 Dev (~2.5s)
"Professional headshot of a business executive, studio lighti..."
Flux 2 Dev (~2.5s) result
Model: flux-2-dev
Professional headshot of a business executive, studio lighting, neutral background, corporate portrait

The decision between these models often comes down to use case rather than absolute quality. Consider: if you're generating 100 images to iterate on a concept, using Schnell takes about 2 minutes. The same batch with Flux 2 Dev takes 4-5 minutes and costs roughly 3.5× more. That's a significant difference for exploration where most images will be discarded.

Conversely, for a single hero image that will appear prominently on your website, the cost difference is negligible compared to the quality improvement. The right choice depends on volume, visibility, and whether the image is exploratory or final.

Tip: A common workflow: iterate quickly with Schnell to find the right prompt, then generate the final version with Flux 2 Dev.

Specifications

Feature Comparison

Technical specifications and capabilities for both models.

FeatureFlux 1 SchnellFlux 2 Dev
Release2024January 2025
ArchitectureFLUX.1FLUX.2 (upgraded)
Image qualityGoodExcellent
Fine detailsBasicVery Good
Generation speed~1s~2.5s
Relative cost~1×~3.5×
Text renderingBasicGood
Prompt adherenceGoodExcellent
Image-to-image
ELO score~1050~1143
Try It Yourself

Try Flux 1 Schnell

Try Flux 1 Schnell with your own prompts. Generate images and compare results. Switch between Fast (Schnell) and Balanced (Flux 2 Dev) routes.

Generated visual
https://demo.staging.imagegpt.host/image?prompt=A+serene+Japanese+garden+with+a+red+maple+tree%2C+stone+lantern%2C+and+koi+pond%2C+morning+mist%2C+golden+hour+lighting&model=flux-1-schnell

Frequently Asked Questions

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