Still plus clip: how many variants $25 buys with Grok Video 1.5

Grok Imagine Video 1.5 on Sume is image-to-video only, so every clip needs a start image. At a Sume billable $0.0125 per second, a 4-second clip is $0.05. Add a GPT Image 2.5 low still ($0.007375) and one variant costs $0.057375, so $25 buys 435 four-second variants. With a Nano Banana 2.1 1K still ($0.10), one variant costs $0.15 and $25 buys 166.

Prices are Sume billable amounts: provider list times 1.25, rounded up to a micro-dollar. Grok Imagine Video 1.5 lists $0.01 per output second at 480p and 720p, which is $0.0125 billable. Its Video Router entry takes 4 to 15 seconds, and it has no end frame, reference inputs or audio toggle.

What does one clip cost by length?

The rate is flat per second, so cost is exactly seconds times $0.0125. Switching between 480p and 720p does not change it.

How does the still change the total?

The still is a separate image job, so a variant is two charges: one image and one clip. The table adds them and divides $25 by the total, rounding the count down.

What does a 20-variant test cost?

A typical creative test is 20 variants at 6 seconds. With GPT Image 2.5 low stills that is 20 times $0.082375, or $1.6475. With GPT Image 2.5 medium stills it is 20 times $0.0915, or $1.83. With Nano Banana 2.1 1K stills it is 20 times $0.175, or $3.50.

The clip is the larger share in the cheap case: $0.075 of the $0.082375 low-still variant. The still is the larger share when you pick Nano Banana 2.1 at 1K, where $0.10 of the $0.175 is the image. Spending more on the still only pays off if the still quality is what you are testing.

Will my wallet count match the table?

The counts above use exact micro-dollar amounts. The Video Router catalog also lists whole-cent amounts rounded up, so if each of your requests were rounded up to a cent, the 4-second low-still figure would be 6 cents per variant and $25 would buy 416 instead of 435. Plan with the lower number if a batch has to fit a hard limit, and read the real amount from the billable field in each job response.