The reserve model in one paragraph
When you submit a batch, Nano Banana reserves prompts × outputs × the per-image cost of your resolution tier. Nothing is charged yet. A credit moves from “reserved” to “spent” only when its output succeeds and becomes downloadable. If a slot ends blocked, failed, timed-out, or cancelled, its reserve is released automatically — you never pay for an image you cannot download.
What counts as failure (and costs you nothing)
Slots can end in several non-success states, all treated the same way by the ledger:
- Blocked — the prompt or reference tripped a safety rule; reserve released.
- Failed — the provider errored or returned nothing usable; reserve released.
- Timed out — the slot exceeded its processing window; reserve released.
- Cancelled — you cancelled the batch before the slot finished; reserve released.
Retries: only the failures, never the whole batch
Because every output sits in a fixed VD-NNN/MM slot, retrying is surgical: you re-run only the failed slots, and each retry reserves (then settles) just those slots' credits. Successful slots are never re-charged, and the contact sheet never reorders — a retried slot lands back in its original position.
Two credit balances, one burn order
Nano Banana credits come in two kinds. Subscription credits (3,300/8,000/25,000 per month by tier) refresh monthly and expire with the monthly cycle. Credit pack credits ($12.90/3,900, $29.90/9,600, $69.90/23,000) never expire.
When you generate, the ledger always burns the soonest-expiring credits first — subscription credits before pack credits — so nothing permanent is spent while expiring credits are still on the table.
Free credits follow the same rules
The 20 sign-up credits and the +2 daily check-in credits live in the same ledger and follow the same success-only rule. Free credits have no cash value and cannot be refunded or exchanged, but they spend exactly like paid ones — including at the 1K/2K tiers open to free accounts.
Where to verify all of this
Every reserve, charge, release, and grant is a line in your credit ledger — check the balance page after any batch and the arithmetic should reconcile to the credit. If a technical defect on our side ever charges you for an output you never received, the refund policy compensates with replacement credits or a proportional refund.