How on-chain deposit confirmations actually work
A confirmation is a block that contains your transaction, plus every block built on top of it. When your deposit lands in a block it has one confirmation; when the next block is added it has two. The count measures how much work would have to be redone to undo your payment.
That definition only fits chains that work like Bitcoin. Ethereum, Solana and Tron do not count confirmations at all — they have their own notions of when a transaction stops being reversible, and comparing their numbers to Bitcoin's is meaningless.
Why depth matters
The newest block on a chain is not settled. Two miners can find a block at the same height, and only one fork survives; a transaction in the losing fork returns to the pending pool as though it never happened. This is a reorganisation, or reorg.
Each additional block makes that harder. Bitcoin's own guidance describes transactions as becoming irreversible gradually rather than at a fixed point, and suggests six confirmations as a minimum for high-value transfers — not because six is magic, but because the cost of rewriting six blocks is prohibitive.
Zero confirmations means only that a transaction was broadcast. It can still be replaced.
Confirmation is not finality
These are different ideas, and the difference is the reason a single number cannot describe every chain.
Confirmation is probabilistic. A Bitcoin transaction six blocks deep is not mathematically final — it is merely so expensive to reverse that nobody rationally would. The probability approaches zero without reaching it.
Finality is a guarantee the protocol itself makes. Some chains have a point after which reversal breaks the rules rather than just costing money, and undoing it would cost validators their stake.
So "6 confirmations" and "finalized" are not two measurements of the same thing.
What the chains actually do
| Chain | How settlement is expressed | Roughly |
|---|---|---|
| Bitcoin | Block depth | ~10 min per block, probabilistic |
| Ethereum | Justified, then finalized checkpoints | Two epochs, ~13 min |
| Solana | Commitment: processed → confirmed → finalized | Sub-second slots |
| Tron | Block solidification | ~1 minute |
Bitcoin counts blocks. Depth is the only measure, and it never becomes absolute.
Ethereum divides time into 12-second slots and 32-slot epochs. The first block of each epoch is a checkpoint; when checkpoint pairs attract votes representing two-thirds of staked ETH they become justified, and then finalized. Reverting a finalized block would require an attacker to lose a very large amount of staked ETH. Ethereum does not have a "number of confirmations" — it has a state a block is in.
Solana uses commitment levels rather than counts. processed is the loosest, confirmed means the slot has been voted on, and finalized is the strongest. A service asking for finalized is not waiting for a block count.
Tron calls it solidification: a block is solidified once enough distinct Super Representatives have built on it, at which point it cannot be replaced by a fork.
Four chains, four models. A service that says "we wait for 6 confirmations" is describing a Bitcoin-style chain, and the phrase does not transfer.
Why block time alone does not tell you the wait
Fast blocks do not mean fast settlement. A chain producing a block every minute with modest security may need far more blocks to reach the same confidence as one producing a block every ten minutes with enormous security. Depth is only meaningful relative to how hard the blocks are to produce.
This is why comparing "12 confirmations here" with "3 confirmations there" tells you almost nothing without knowing what each chain's block costs to make.
Visible is not the same as settled
A transaction appearing in a block explorer means it was broadcast and probably included. It does not mean a service should act on it, and this gap causes most "my transaction is confirmed but my swap is still pending" confusion.
A service watching for your deposit has to consider more than visibility:
- Depth or finality — is it settled enough that a reorg will not undo it?
- Amount — does what arrived match what was expected?
- Timing — did it arrive within the funding window?
- Completeness — did all of it arrive, or only part?
Any one of those can hold a deposit that an explorer already shows as confirmed. The explorer is answering "did this happen?" The service is answering "is it safe to send my own funds against this?"
On SwapToZec
Bitcoin deposits require 2 confirmations. It is a deliberate trade-off: deep enough that a reorg is unlikely at the sizes involved, shallow enough that customers are not waiting an hour.
Two things about that number are commonly misunderstood.
Reaching it does not release a payout. Confirmations are a precondition, not a trigger. Once a Bitcoin deposit is verified as exact and sufficiently confirmed, the swap becomes eligible for payout — an operator then reviews and sends it. No automated process sends funds out on reaching a confirmation count.
It is a Bitcoin number and does not generalise. Bitcoin is the network with automated deposit monitoring. On the other networks a deposit is checked by a person by design, so there is no automatic confirmation threshold to quote for them — and publishing one would mean describing a rule that does not operate. What you should expect there is the same requirement that the amount match, checked by a person rather than by software.
If a deposit is exact and sufficiently confirmed but arrives after the funding window closed, it is routed to review rather than processed or discarded — see what "expired" means on a crypto swap.
While you wait
- Watch the status page for your swap. It shows the confirmation count and the current state.
- Do not send a second deposit. A transaction that has not confirmed has not failed. Two deposits become a review case, not a larger swap.
- A low fee means a longer wait, not a lost payment. On Bitcoin an underpriced transaction can sit pending for a long time and still confirm.
- Keep the transaction hash. It is the first thing any support question needs.
Related
- Why a swap asks for an exact deposit amount
- What happens if you send crypto on the wrong network
- Zcash transaction fees and confirmation times — the receiving side
Sources: Ethereum proof-of-stake documentation, Solana transaction confirmation guide, TRON consensus documentation.