Confirmations: why 'confirmed' is a probability, not a switch
A transaction gets one confirmation when its block is mined, and more as blocks stack on top. Depth makes reversal exponentially harder — which is why pools wait for N confirmations before crediting your payout.
2026-10-19·updated 2026-10-19·3 min·pow.family research#bitcoin#mechanics
01
Depth, not truth
A transaction is 'in a block' after 1 confirmation — the block containing it was mined. Each subsequent block on top adds one more. To undo a transaction with N confirmations, an attacker must re-mine that block AND all N−1 after it, faster than the honest network extends the chain. Every extra confirmation multiplies the cost of that rewrite.
0 conf
mempool
unconfirmed — replaceable in many wallets
1 conf
mined
reversible only by re-mining one block
6 conf
convention
historic Bitcoin merchant standard for large payments
100 conf
coinbase rule
block rewards themselves are spendable only after 100 blocks
02
What this means for miners
- Pool payouts list 'N confirmations' before funds show as sendable — small chains vary from a few blocks to 100+.
- A chain reorg (rare, usually 1–2 blocks deep) can briefly un-confirm transactions; exchanges then pause withdrawals.
- Your pool dashboard's 'pending balance' is pre-confirmation; 'paid' plus N confirmations is money you can spend.
03
See it live on pow.family
Every coin page lists block interval and confirmation norms — the two numbers that set how long you wait from 'pool paid' to 'wallet holds'.