Nano Banana 2.1 vs Seedream 5.0: 8 Side-by-Side API Tests
- 1. Quick Verdict
- 2. How We Tested
- 3. Text Rendering
- 4. Prompt Adherence: The Counting Test
- 5. Editing With Reference Images
- 6. Photorealism
- 7. Wide 21:9 Landscapes
- 8. Speed and Price
- 9. Which One Should You Use?
- 10. FAQ
- 11. Sources
1. Quick Verdict
Google's Nano Banana 2.1 (October 2026) and ByteDance's Seedream 5.0 Pro (July 2026) are two of the strongest image models you can call through an API today. We ran both through the GoEnhance API with the same eight prompts at 1K and compared the results side by side. Short version: both render text very well, Seedream 5.0 Pro is cheaper per image through the API, and Nano Banana 2.1 is more than twice as fast and more reliable on exact instructions.
| Nano Banana 2.1 | Seedream 5.0 Pro | |
|---|---|---|
| Text spelling (menu, infographic, bilingual poster) | 3 of 3 correct | 3 of 3 correct |
| Added text nobody asked for | Rarely | Rarely (a small seal on one product) |
| Counting test (7 apples + 3 pears) | Correct | Wrong, drew 8 apples |
| Kept the character when editing | Yes | Yes |
| Followed "at sunset" in the landscape | Yes | Lighting closer to late afternoon |
| Median time per image (1K, our run) | 18.9 s | 47.0 s |
| API price at 1K (tokens) | 2.92 | 1.725 |
| Highest resolution | 4K | 2K (Seedream 5.0 Lite goes to 4K) |
| On GoEnhance studio | 6 / 9 / 17 tokens (1K / 2K / 4K) | 18 / 36 tokens (1K / 2K) |
| Reference images per edit | Up to 9 | Up to 10 |
2. How We Tested
Every image in this post comes from one API call per model through the GoEnhance image API on October 8, 2026:
- Models:
nano-banana-2-1(andnano-banana-2-1-editfor edits) againstseedream-5-pro, which handles both text-to-image and editing in one model. - Settings: 1K for both. Nano Banana 2.1 used its default thinking level. Seedream 5.0 Pro offers 1K, 1.5K and 2K; we used 1K so both models output the same resolution.
- Prompts: the same eight prompts as our Nano Banana 2.1 vs GPT Image 2.5 test, so you can compare all three models on identical inputs. The Nano Banana 2.1 images are from that run, earlier the same day.
- Timing: measured from submitting the job to the job reporting success, so it includes queue time.
One run per prompt is not a benchmark. Treat this as a hands-on comparison of how the two models behave on the same input. Sources are listed at the end.
3. Text Rendering
ByteDance describes Seedream 5.0 Pro as strong at text rendering and dense information layouts, and that showed.
Chalkboard menu. Six items with prices. Both models spelled everything correctly. Seedream 5.0 Pro produced the cleanest board of any model we have tested, with tidy dotted leaders between items and prices and nothing extra. Nano Banana 2.1 went for a more decorative, colourful board with small icons.
Infographic. "The Water Cycle" with four labelled stages. Both got every label right and drew the cycle in the correct order. Seedream 5.0 Pro used a lighter, more minimal layout; Nano Banana 2.1 used larger labels that read better at small sizes.
Bilingual poster. An English headline, a Chinese line and a caption, with a minimal layout. Both rendered the English and Chinese correctly. Seedream 5.0 Pro made the more polished poster, with fresh tea leaves and an engraved landscape on the tin, plus a small red seal with the character for tea. Nano Banana 2.1 left the tin plain.
Takeaway: for text, this is the closest matchup we have run. Both are reliable, and neither added slogans or labels the way GPT Image 2.5 did in our previous test.
4. Prompt Adherence: The Counting Test
"Exactly seven red apples and three green pears in a single row." Nano Banana 2.1 got it right. Seedream 5.0 Pro drew eight apples and three pears. It is one prompt, but if your work depends on exact quantities, such as product counts or a grid of icons, check Seedream's output carefully.
5. Editing With Reference Images
Single reference. We asked both models to take an orange robot from a 2x2 grid and place it alone on the Moon, planting a flag. Both kept the round head, glowing blue eyes and green scarf. Seedream 5.0 Pro posed the robot facing the camera with a large flag; Nano Banana 2.1 used a side angle and added Moon dust.
Two references. The robot (image 1) holding a green ceramic mug (image 2) in a kitchen. Both kept the robot and the mug recognisable. Seedream 5.0 Pro opened the window onto a rose garden; Nano Banana 2.1 kept a classic wooden kitchen. A tie.
Seedream 5.0 Pro accepts up to 10 reference images on the GoEnhance API, and the first one is free; Nano Banana 2.1 accepts up to 9.
6. Photorealism
A candid photo of an elderly fisherman mending a net at golden hour. Both are convincing. Seedream 5.0 Pro's version is warmer and more candid, with a smile and other fishermen in the background; Nano Banana 2.1's looks more like a staged documentary portrait with stronger backlight.
7. Wide 21:9 Landscapes
A coastal road with a single red car "at sunset". Both produced a clean, coherent panorama with the red car in place. Nano Banana 2.1 delivered a real sunset with orange skies; Seedream 5.0 Pro's light looks more like late afternoon.
8. Speed and Price
Nano Banana 2.1 had a median of 18.9 seconds per image (15 to 22 s). Seedream 5.0 Pro had a median of 47 seconds (36 to 104 s), with the two editing jobs the slowest.
On the GoEnhance API, 1 token = $0.02:
| Setting | Nano Banana 2.1 | Seedream 5.0 Pro |
|---|---|---|
| 1K | 2.92 tokens | 1.725 tokens (1.5K costs the same) |
| 2K | 4.02 tokens | 3.45 tokens |
| 4K | 8.08 tokens | Not available (Seedream 5.0 Lite: 1.65 tokens at 2K, 3K or 4K) |
| Extra reference images | Included | 0.115 tokens each after the first |
Through the API, Seedream 5.0 Pro is about 40% cheaper at 1K and still cheaper at 2K. If you need 4K, Nano Banana 2.1 or Seedream 5.0 Lite are the options.
The GoEnhance studio is the other way round: Seedream 5.0 Pro costs 18 tokens at 1K and 36 at 2K and is for members, while Nano Banana 2.1 costs 6, 9 or 17 tokens and 1K is open to everyone. Seedream 5.0 Lite is 16 tokens per image.
9. Which One Should You Use?
Choose Nano Banana 2.1 if you need speed, exact counts and lighting cues, or 4K output, or if you work in the GoEnhance studio, where it is the cheaper model.
Choose Seedream 5.0 Pro if you call the API at volume and want the lowest price per image, if you design clean text-heavy layouts such as menus and price lists, or if you want warm, candid photography. Check counts and lighting before you publish.
Use both for text-heavy design: generate a clean layout with Seedream 5.0 Pro, then use Nano Banana 2.1 for fast variations and edits.
For more on each model, see our Nano Banana 2.1 page and Seedream 5.0 page, or the earlier Seedream 4.5. To see how Nano Banana 2.1 compares with other models, read our Nano Banana 2.1 vs Nano Banana 2 and Nano Banana 2.1 vs GPT Image 2.5 tests.
10. FAQ
Is Nano Banana 2.1 better than Seedream 5.0? Neither wins outright. They matched on text rendering. Nano Banana 2.1 was faster and more exact on counts and lighting; Seedream 5.0 Pro was cheaper through the API and produced the cleanest menu layout.
Which one renders text better? Both spelled every requested word correctly in our three text tests, in English and Chinese. Seedream 5.0 Pro's layouts were slightly cleaner; Nano Banana 2.1's labels were larger and easier to read at small sizes.
Which is cheaper? Through the GoEnhance API, Seedream 5.0 Pro (1.725 tokens at 1K) is cheaper than Nano Banana 2.1 (2.92). In the GoEnhance studio it is the reverse: Nano Banana 2.1 costs 6 tokens at 1K against 18 for Seedream 5.0 Pro.
What is the difference between Seedream 5.0 Pro and Lite? Pro is the flagship, released in July 2026, with output up to 2K. Lite came first, in February 2026; it outputs at 2K, 3K or 4K for one flat price and adds real-time web search. We tested Pro.
11. Sources
- ByteDance Seed, Introducing Seedream 5.0 Pro (July 8, 2026): text rendering, information visualization and multilingual generation.
- ByteDance Seed, Introducing Seedream 5.0 Lite (February 13, 2026): reasoning and real-time search.
- Google AI for Developers, Nano Banana 2.1 model page: capabilities, supported ratios and reference image limits.
- GoEnhance API docs, seedream-5-pro, seedream-5-lite and nano-banana-2-1: parameters, reference image limits and per-image prices used in this test.
- Our own test: 16 API jobs run on October 8, 2026, one per prompt and model; every image in this post is unedited apart from resizing and labels.
