Will my Seedream 5.0 Pro prompts work on 5.5?

The wording will, and every prompt here ran unchanged on both. The results will differ in framing, so re-check anything tuned to a specific look. Some request settings need changing first; the table above lists them.

Does Seedream 5.5 have a seed or a negative prompt?

No, and neither does 5.0 Pro on SpicyAPI, so you cannot reproduce an exact image on either model. Expect each run of the same prompt to come out differently.

Should I switch from Seedream 5.0 Lite or Flash instead?

We did not run those two in this test. At 1K, 5.5 costs less per image than either, but check your own prompts before moving.

Seedream 5.5 vs 5.0 Pro: Same-Prompt Test, Should You Switch?

Which jobs to move

Your job	Use	Why
Signs, labels or posters in several scripts	5.5	22 of 22 lines correct against 7 of 22. 5.0 Pro broke Arabic, Thai, Hindi, Greek and Russian in both runs.
Revising one image again and again	5.5	After six edits the untouched areas barely moved. On 5.0 Pro the person shifted and the face was redrawn.
High-volume drafts	5.5	$19.50 per 1,000 images at 1K against $36, and $27 at 2K against $72.
4K delivery	5.5	5.0 Pro stops at 2K.
Latin and short Japanese or Korean copy	Either	Both got all 11 lines right in both runs. 5.0 Pro kept the layout straighter.
Portraits	Either	We saw no clear winner, in our runs or in the blind test.
4:5 feed images, 2:1 banners, 3:1 strips	5.0 Pro	5.5 rejects these shapes.
Batch edits on mixed source shapes	5.0 Pro	It can follow the source shape automatically. 5.5 cannot.

We ran every prompt on both models on 7 November 2026, through SpicyAPI, at the same resolution and in PNG. Each prompt ran twice per model, and we scored text by reading every line. The whole test cost $1.01. Two runs is enough to show a large gap, not to measure a small one, so treat the “Either” rows as “no difference we could see”.

Text: the gap appears when the script gets harder

We asked both models for a hotel safety notice: a title, nine language lines and a tiny footer. Seedream 5.5 got all 11 lines right in both runs. Seedream 5.0 Pro got three right in one run and four in the other. It kept the title, the English line and the footer, then fell apart on anything less common.

Printed safety notice on a cork board with cleanly set lines in nine languages — Same prompt, 2K, first run of two. On the right, look at the Greek, Arabic, Thai and Hindi lines: they resemble those scripts without being words. A reader of those languages would spot it instantly, which makes this a real risk for anything that gets printed.

The same notice with several lines reduced to malformed characters — Same prompt, 2K, first run of two. On the right, look at the Greek, Arabic, Thai and Hindi lines: they resemble those scripts without being words. A reader of those languages would spot it instantly, which makes this a real risk for anything that gets printed.

The errors are easy to miss if you cannot read the language. Both 5.0 Pro runs also slipped on Korean and Japanese while looking tidy at a glance. If your output carries languages nobody on the team reads, this result alone justifies moving.

Easier copy is a different story. On a café price card with English, Japanese, Korean and accented Latin text, both models got all 11 lines right in both runs. Here 5.0 Pro had the edge on layout: it kept the card square to the camera, while 5.5 tilted it in both runs.

Cream price card lying at an angle on a marble counter — Both cards are correct. The difference is composition, which matters if you need a clean flat layout. Prices on the left line up once you allow for the tilt.

The same price card squared to the camera with an even price column — Both cards are correct. The difference is composition, which matters if you need a clean flat layout. Prices on the left line up once you allow for the tilt.

Repeated edits: 5.5 leaves the rest of the picture alone

ByteDance says 5.5 stays stable over more than 100 editing rounds. We tried six. Starting from one photo made by a third model, so neither side was editing its own work, each model made the same six small changes in sequence: mug, sweater, poster, pen, book, phone. Every instruction ended by asking to keep everything else the same.

A woman working on a laptop at a desk in a bright room with a clock, poster and plants — The starting image, before any edit.

The same room with a red mug, green sweater and sea poster, otherwise unchanged — Both models made all six changes. On the right the person has moved, the contrast has climbed, the clock has changed, the small plant at the bottom has gone and the poster has gained words nobody asked for.

The same room with the person moved to the right, harsher contrast and invented poster text — Both models made all six changes. On the right the person has moved, the contrast has climbed, the clock has changed, the small plant at the bottom has gone and the poster has gained words nobody asked for.

To put a number on it, we compared areas no instruction touched with the starting image, after all six rounds. A figure near zero means those pixels did not change.

Untouched area	Seedream 5.5	Seedream 5.0 Pro
Her face	1.5%	26.9%
Window and fern	0.9%	7.1%
Wall clock	0.5%	6.1%
Bare wall	0.5%	7.4%

The damage on 5.0 Pro built up: small at first, then a jump at round four, when the person moved. That is the pattern to watch for, since a single edit can look fine and still start the slide. If you must stay on 5.0 Pro, edit from the original each time rather than from the last result. This is one chain per model at 1K, so it shows a clear difference on this image, not a rate.

Portraits: pick by framing, not by version

We asked for a carpenter at work, with both hands on a chisel. Neither model produced obviously broken hands in four runs. Seedream 5.5 stepped back and showed more of the workshop, while 5.0 Pro went closer, with harder light and more texture in the skin. Neither looks like a generation ahead of the other.

A carpenter at a bench seen from a distance with the workshop behind him — Same prompt, 2K, second run of two. ByteDance says faces and materials look more natural on 5.5. We could not see that here.

A closer view of a carpenter driving a chisel into a block of oak — Same prompt, 2K, second run of two. ByteDance says faces and materials look more natural on 5.5. We could not see that here.

The blind test agrees. On the same 14 prompts, AI judges from three companies gave 5.5 a score of 76.8 and 5.0 Pro 76.3, too close to separate. The 78.8 you may see for 5.0 Pro comes from a larger prompt set, so do not compare it with 76.8 directly. If image quality is your only reason to move, you do not have one yet.

Transparent output: a clean outline, but solid glass

Seedream 5.5 can return a transparent PNG straight from a prompt, which saves a background-removal step that 5.0 Pro still needs. There is a catch for product work. We asked for a glass bottle and checked the alpha channel: the outline is cut cleanly, but the glass itself is 100% opaque, so a background placed behind it will not show through.

A perfume bottle with a gold cap cut out on a checkerboard — Seedream 5.5, one run at 2K. The upper glass stays bright on dark, because its lighter tone is painted in rather than see-through. The label and crest were invented: the prompt asked for neither.

The same bottle on a dark background with its glass still bright — Seedream 5.5, one run at 2K. The upper glass stays bright on dark, because its lighter tone is painted in rather than see-through. The label and crest were invented: the prompt asked for neither.

That is fine for solid products. For glass, liquids or smoke, plan on compositing by hand.

When to stay on 5.0 Pro

You publish in shapes 5.5 dropped. 4:5, 5:4, 9:21, 2:1, 1:2, 3:1 and 1:3 are gone, and 4:5 is the usual tall feed format. Cropping from 3:4 works for one image but changes your composition rules across a batch.
Your pipeline edits mixed source shapes. 5.0 Pro can follow the source with an automatic ratio. 5.5 has no such setting and defaults to square, so you would have to read each source and map it to one of eight ratios, and any shape outside those eight gets reframed.
You have a look you trust. If a project is tuned to 5.0 Pro, the framing changes shown above will move your results, so re-test before you switch a live job.

If you do switch an existing integration, changing the model ID is not quite enough. These are the differences to plan for. We confirmed the three rejections against the live API:

In your 5.0 Pro request	On 5.5	What to do
A dropped aspect ratio	Rejected with an error	Map it to one of the eight ratios, or keep that job on 5.0 Pro
Automatic ratio on an edit	Rejected with an error	Send the ratio that matches the source
No ratio on an edit	Output comes back square	Always send a ratio
The thinking setting	Rejected with an error	Remove the field
No format set	PNG instead of JPEG	Set JPEG if file size or storage matters

What you would pay and wait

Job	Seedream 5.5	Seedream 5.0 Pro
1K image	$0.0195	$0.036
2K image	$0.027	$0.072
4K image	$0.0525	Not offered
1K edit, one source image	$0.027	$0.036
2K edit, one source image	$0.0345	$0.072
Time per image in our runs	26 to 59 seconds, median 33	44 to 145 seconds, median 55
Time per edit in our runs	22 to 38 seconds	38 to 116 seconds

Prices are SpicyAPI quotes from 7 November 2026, and refused or failed runs are not charged. Times include the queue and come from one evening, so read them as “5.5 was usually quicker”, not as a guarantee. The largest saving is at 2K, the default size on both models, where an image costs 62% less and an edit 52% less.

Layer splits are the one job where the budget works differently. 5.5 lets you cap the output, so a split limited to six images was quoted at $0.117 at 1K. 5.0 Pro has no cap and held $0.714 on the same image. We compared quotes only and did not run this one.

If NSFW range is part of your decision

It should not change the answer. Neither model refused a run, and they deliver at a similar rate: 52 of 54 on 5.5 and 37 of 38 on 5.0 Pro. The level-by-level results are in the Seedream 5.5 test on SpicyAPI, and every other version is in our Seedream family note.

Seedream 5.5 vs 5.0 Pro: which jobs to switch, and which to leave alone