FLUX.1 Kontext [max] is the higher tier of Black Forest Labs' FLUX Kontext, released in May 2025. It works like [pro]: you edit an image by describing the change, with no mask, or generate from text. The difference is stronger typography and prompt adherence, which matters when an edit involves lettering or several precise instructions. It accepts up to 4 reference images and 9 aspect ratios, and every output renders at about 1 MP, one image per request.
Best for
- Localizing text on packaging, posters and screenshots
- Edits that combine several specific instructions in one prompt
- Logo and label mockups where every letter must be right
- Product variants that keep the shot but change color or copy
Prompting tips
- Quote the exact text and describe its font style, color and position.
- List instructions in order when an edit has several parts.
- Keep a
seedfixed while you refine the wording. - Combine up to 4 references, for example a product photo plus a style sample.
FAQ
How much does FLUX.1 Kontext [max] cost?
It is $0.176 per image at current Jantaris pricing. Failed generations are not charged, and the estimated cost is returned before the task starts.
When is Kontext [max] worth it over [pro]?
When text in the image must be correct or the prompt carries several precise instructions. For simpler edits, FLUX.1 Kontext [pro] takes the same inputs.
What resolution does FLUX.1 Kontext [max] output?
About 1 MP in any of its 9 aspect ratios.
How to call FLUX.1 Kontext [max] via API
curl https://jantaris.com/v1/generate?wait=60 \
-H "Authorization: Bearer $JANTARIS_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "flux-kontext-max",
"input": {
"prompt": "Product photo of a matte black ceramic coffee cup on a travertine table, soft window light, 50mm",
"aspect_ratio": "1:1"
}
}'import os, time, requests
API = "https://jantaris.com/v1"
H = {"Authorization": f"Bearer {os.environ['JANTARIS_API_KEY']}"}
task = requests.post(f"{API}/generate", headers=H, json={
"model": "flux-kontext-max",
"input": {
"prompt": "Product photo of a matte black ceramic coffee cup on a travertine table, soft window light, 50mm",
"aspect_ratio": "1:1"
}
}).json()
while task["status"] in ("queued", "running"):
time.sleep(3)
task = requests.get(f"{API}/tasks/{task['id']}", headers=H).json()
print(task["status"], task["cost"], [o["url"] for o in task["output"]])const API = "https://jantaris.com/v1";
const headers = { Authorization: `Bearer ${process.env.JANTARIS_API_KEY}`, "Content-Type": "application/json" };
let task = await (await fetch(`${API}/generate`, {
method: "POST",
headers,
body: JSON.stringify({
"model": "flux-kontext-max",
"input": {
"prompt": "Product photo of a matte black ceramic coffee cup on a travertine table, soft window light, 50mm",
"aspect_ratio": "1:1"
}
}),
})).json();
while (task.status === "queued" || task.status === "running") {
await new Promise((r) => setTimeout(r, 3000));
task = await (await fetch(`${API}/tasks/${task.id}`, { headers })).json();
}
console.log(task.status, task.cost, task.output.map((o) => o.url));Parameters
| Parameter | Type | Allowed | Default |
|---|---|---|---|
prompt * | string | ||
aspect_ratio | string | 1:1 4:3 3:4 16:9 9:16 3:2 2:3 21:9 9:21 | 1:1 |
num_images | integer | 1-1 | 1 |
image_urls | array | max 4 | |
seed | integer |
The same schema is available from GET /v1/models/flux-kontext-max.
