Seedream 5 Lite is 12.5% cheaper than 4.5 on Sume: 4.375 vs 5 cents

Seedream 5 Lite is 12.5% cheaper than Seedream 4.5 on Sume: $0.04375 against $0.05 per image. Over 1,000 images the difference is $6.25, and over 10,000 it is $62.50. Both rows list the same 9 aspect ratios (1:1, 16:9, 9:16, 4:3, 3:4, 4:5, 5:4, 3:2, 2:3), take up to 10 reference images, and accept image_size, so for a flat-price job the decision usually comes down to the price and to how the output looks on your own prompts.

The numbers

Seedream 4.5 lists at $0.04 and Seedream 5 Lite at $0.035 in the repo's pricing table. Each is multiplied by 1.25 for the Sume price: 0.04 x 1.25 = 0.05 and 0.035 x 1.25 = 0.04375. The saving is 0.00625 per image, which is 0.00625 / 0.05 = 12.5%.

What is the same

Both rows are in the Seedream family on the catalog, both are edit-capable with the shared 10-reference ceiling, and neither lists quality or resolution. You choose size with image_size or aspect_ratio only, so there is no cheaper tier to move to on either row.

What we do not claim

Sume does not rank the two on output. A lower price does not say which one is better for text, faces or product shots. Run the same prompt on both and keep the better. At $0.09375 for the pair, an A/B costs less than a dime.

If you also compare against other flat rows, Flux 2 Pro is $0.0375 and Qwen Image is $0.025, so Seedream 5 Lite sits between them and Seedream 4.5.

Compute it

Keep the arithmetic in decimal.

from decimal import Decimal as D

old, new = D("0.04") * D("1.25"), D("0.035") * D("1.25")
print(old, new, (old - new) / old * 100)
for n in (1, 100, 1000, 10000):
    print(n, old * n, new * n, (old - new) * n)

When the saving matters

At 100 images a month the saving is $0.625, which does not decide anything. At 10,000 it is $62.50, which is worth one A/B test. A catalog refresh of 5,000 product images saves $31.25 on the cheaper row, which is still less than most teams spend on the time to review the output.

Also count retries. If the cheaper row needs a second attempt on one image in eight, the saving disappears, since 8 images at $0.04375 plus one retry is 9 x $0.04375 = $0.39375 against 8 x $0.05 = $0.40. That is only a 0.625 cent gap, so the output has to be right the first time to matter.

Check GET /v1/images/models/bytedance-seed/seedream-5-lite/endpoints and the 4.5 equivalent before a large run. Both return a pricing line with cost_usd, which already includes the Sume margin. If the two numbers ever converge or cross, this post is out of date and the live record wins.