Carousel vs 15-second Reel: cost per post and per 30-post month

A carousel of eight slides costs $0.132 on GPT Image 2.5 at medium quality, while a 15-second finished Reel on Wan 3.0 costs $2.31. Thirty carousels cost $3.96 a month and thirty Reels cost $69.32, which makes the Reel about 18 times as expensive per post.

That ratio is the reason to plan the mix on purpose. All figures are Sume billable amounts (provider list times 1.25) read on 2026-10-03; eight slides and a 15-second Reel are our planning shapes, and the Reel's narration assumes 15 characters per second.

Cost per post

A carousel is images only. A Reel is a clip plus a finishing stack of narration, a caption job at $0.20, a Timeline minute at $0.10 and a music track at $0.125. The finishing stack alone is $0.44 for a 15-second piece, which is more than a GPT Image 2.5 carousel costs end to end.

Ideogram and Nano Banana carousels need no finishing step, but their per-image rates are higher than GPT Image 2.5 medium.

Mixing formats

The cheapest calendar is not always the best one, but the mix is easy to price. Replace half of a month's Reels with carousels and the bill falls by roughly half of the Reel cost.

Prices for three mixes follow.

What the comparison leaves out

Cost per post is not cost per result. A carousel may keep viewers swiping through eight slides for the same time a Reel holds them for fifteen seconds, or it may not; Sume's price list says nothing about performance, and this post does not claim any. What it does give is the price of finding out.

A test is cheap: ten carousels on GPT Image 2.5 medium cost $1.32, and ten 15-second Wan Reels cost $23.11. Run both for a month on the same topics and compare views against spend.

What Sume does and does not do

Sume produces the images and clips and prices each at submit. It does not publish or measure them. Confirm rates in the catalog.

Rerun the arithmetic

The same line items as a short script, so you can change a quantity and see the total. It is plain arithmetic on the rates in this post; it does not call the Sume API.

# Sume billable USD rates, read 2026-10-03. Edit the quantities.
lines = [
    ('Carousel slides (GPT Image 2.5 medium), 15 x 8', 120, 0.0165),
    ('Reel clip seconds (Wan 720p), 15 x 15', 225, 0.125),
    ('Narration characters, 15 Reels', 3375, 0.0000475),
    ('Caption jobs', 15, 0.20),
    ('Timeline minutes', 15, 0.10),
    ('Music tracks', 15, 0.125),
]
total = 0.0
for label, qty, unit in lines:
    cost = qty * unit
    total += cost
    print(f"{label:<46}{qty:>8g} x {unit:<10g} = ${cost:,.2f}")
print(f"{'Total':<46}{'':>8}   {'':<10}   ${total:,.2f}")