Nano Banana 2 on Runway (5 to 16 credits) vs Google direct per image

Runway sells Nano Banana 2 (Gemini 3.1 Flash Image) at 5, 7, 11 and 16 credits per image, which is $0.05, $0.07, $0.11 and $0.16. Google's own page lists a range of about $0.045 to $0.151 per image across sizes, so Runway's markup is about 11% at the cheap end ($0.05 / $0.045) and about 6% at the top ($0.16 / $0.151). On Sume the Image Router default estimate for Nano Banana 2 is $0.10.

Credit prices are from Runway and Google's range from its Gemini API pricing page (both read 2026-10-04).

Reading the ratios

Runway's four credit prices are $0.05, $0.07, $0.11 and $0.16. Dividing the lowest by Google's lowest gives 0.05 / 0.045 = 1.11, and the highest by Google's highest gives 0.16 / 0.151 = 1.06. I matched the endpoints of each range because the Google page I read gives the range and not each size label, so the middle tiers are not compared one to one.

Sume bills provider list x 1.25. The router's default table has Nano Banana 2 at $0.08 per image at default quality, so $0.08 x 1.25 = $0.10. That default tier is not the cheapest size, so the Sume estimate sits above the low-end rows above and should be compared at the same output size before you buy.

Which route fits

• Pure image volume at the smallest size: Google direct, then Runway at 11% more.
• Image generation inside a larger video job: a single balance on Runway or Sume saves account juggling.
• Output size above 2K: check the top tier, where the gap between Google and Runway narrows to 6%.

Steps

• Pick the output size you really need; a 4K image at 16 credits costs more than three of the cheapest tier.
• Multiply count by the per-image price: 10,000 images at $0.05 is $500.00, at $0.045 is $450.00.
• Run ten test prompts and count retries.

A 5,000-image month

At the lowest tier, 5,000 images cost 5,000 x $0.045 = $225 on Google and 5,000 x $0.05 = $250 on Runway. At the highest tier it is $755 against $800. The Runway premium is $25 to $45 for the month, which is small enough that workflow, not price, usually decides.

Caveats

Google's cheaper Flash Lite Image variant is listed around $0.0336 for a 1K image, so a lite model is cheaper than any row in the table if its quality is enough. Prices read 2026-10-04.