FLUX Historical Versions

FLUX.1 [pro] / [pro] 1.1 / [pro] 1.1 Ultra / [dev] specs, pricing, and migration guidance to FLUX.2

This page covers FLUX.1 [pro] text-to-image models that are still callable on APIYI. The latest FLUX.2 generation and the editing-focused FLUX.1 Kontext are documented in the FLUX Overview.

Version Snapshot

Model ID	Released (UTC+0)	APIYI Price	Status	Best For
flux-pro-1.1-ultra	2024-11	$0.0500	🟡 Maintained	Legacy ultra-resolution (4MP)
flux-pro-1.1	2024-10	$0.0350	🟡 Maintained	Legacy text-to-image baseline
flux-pro	2024-08	$0.0400	🟡 Maintained	First-gen pro, legacy compat
flux-dev	2024-08	$0.0200	🟡 Maintained	Dev/test, open-weights local inference

For new projects, prefer FLUX.2: flux-2-pro matches flux-pro-1.1’s tier with major upgrades in quality, multi-reference, long prompts, and 4MP output — at similar or lower cost. See migration guidance below.

Per-Version Specs

flux-pro-1.1-ultra

• Released: 2024-11 (UTC+0)
• APIYI Price: $0.0500 (official $0.06, saves 17%)
• Max output: ~4MP (highest in FLUX.1 series)
• Key features: Ultra-resolution, optional raw mode (closer to candid photography)
• Known limits: Single reference only, no hex color control, no grounding search
• Official docs: docs.bfl.ai/flux_models/flux_1_1_pro_ultra_raw

flux-pro-1.1

• Released: 2024-10 (UTC+0)
• APIYI Price: $0.0350 (official $0.04, saves 12.5%)
• Max output: ~1.6MP (e.g., 1024×1536)
• Key features: Improved quality and prompt adherence over 1.0, industry baseline
• Known limits: Single reference, short prompts (no 32K)
• Official docs: docs.bfl.ai/flux_models/flux_1_1_pro

flux-pro

• Released: 2024-08 (UTC+0)
• APIYI Price: $0.0400 (official $0.04, same)
• Max output: ~1.6MP
• Key features: BFL’s first commercial pro, baseline text-to-image
• Known limits: Quality and adherence below 1.1 — no reason for new projects

flux-dev

• APIYI Price: $0.0200
• Max output: ~1MP
• Key features: Open-weights variant (FLUX.1 [dev], non-commercial license), self-host on your own GPU
• Known limits: Quality below the [pro] tier, mainly for research, prototyping, local inference validation
• Official weights: huggingface.co/black-forest-labs/FLUX.1-dev

Migration Guidance

1. Assess differences

   FLUX.2 fully supersedes FLUX.1 [pro]: 4MP output (vs 1.6MP), up to 8 multi-references (vs 1), 32K-token prompts (vs short), native hex color control, typography specialist tier. Pricing within 1MP is similar or lower.

2. Run side-by-side

   Generate the same prompt set on flux-pro-1.1 and flux-2-pro for a week. Compare text legibility, multi-object consistency, brand color fidelity. FLUX.2 [pro] wins across the board in most cases.

3. Roll out gradually

   Cut 10% of traffic to flux-2-pro first, observe quality and cost for a week, then ramp to 100%. Costs are roughly equivalent at 1MP and noticeably cheaper at 4MP.

4. Handle parameter differences

   Most parameters carry over, but note:

   • FLUX.1 [pro] takes a single reference image; FLUX.2 supports multiple references (JSON fields input_image ~ input_image_8, up to 8)
   • FLUX.1 doesn’t support prompt_upsampling; FLUX.2 [pro/max/flex] does
   • Some legacy aspect-ratio identifiers (e.g., aspect_ratio) are replaced by width/height or the size string in FLUX.2

Legacy Call Example

{/* Call any historical version by changing only the model field — all other params are OpenAI Images API compatible */}
from openai import OpenAI
import requests

client = OpenAI(api_key="sk-your-api-key", base_url="https://api.apiyi.com/v1")

resp = client.images.generate(
    model="flux-pro-1.1-ultra",
    prompt="A serene mountain landscape at golden hour, raw photo style",
    size="2048x1536"
)

# data[0].url is valid for only 10 minutes
url = resp.data[0].url
with open("legacy.jpg", "wb") as f:
    f.write(requests.get(url, timeout=30).content)

Cost Comparison

By typical volume (flat per-image price):

Version	APIYI Price	100 images	1,000 images	10,000 images
flux-pro-1.1-ultra	$0.05	$5.00	$50.00	$500.00
flux-pro-1.1	$0.035	$3.50	$35.00	$350.00
flux-pro	$0.04	$4.00	$40.00	$400.00
flux-dev	$0.02	$2.00	$20.00	$200.00
flux-2-pro (new)	$0.03	$3.00	$30.00	$300.00
flux-2-max (new)	$0.07	$7.00	$70.00	$700.00

How to choose: For new projects, prefer FLUX.2 (flux-2-pro for general use, flux-2-max for flagship). Keep FLUX.1 [pro] running only when legacy integrations are deeply wired and regression testing is impractical. flux-dev remains a viable low-cost dev/test option.

Related Docs

• FLUX Overview — full model matrix and selection
• Text-to-Image Playground — works for FLUX.2 + FLUX.1
• Image Editing Playground — multi-reference fusion + edit