Bitcoin Confirmations: What Are They and How Many to Wait For?

When checking the status of a sent payment in your bitcoin wallet or a block explorer, you will see a field labeled Confirmations.

A transaction with "0 confirmations" is still sitting in the mempool and is not yet final. The moment it gets mined, it receives its first confirmation.

To understand why wait times differ and why merchants require multiple confirmations, you must understand the concepts of block depth and chain finality.

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⛓️ What is a Confirmation?

A confirmation represents a single block mined onto the blockchain that includes your transaction.

As time passes and more blocks are solved, they are added directly on top of the block containing your transaction. Each block mined on top increases your transaction's confirmation count (or depth) by one.

                      [ Block 102 (Latest) ]  ──► 3 Confirmations (Extremely Secure)
                      [ Block 101 ]           ──► 2 Confirmations (Highly Secure)
[ Block 100 ] ────────► Contains Your TX      ──► 1 Confirmation (Secure)

• 1 Confirmation: Your transaction is mined in Block 100.
• 2 Confirmations: Block 101 is mined on top of Block 100.
• 3 Confirmations: Block 102 is mined on top of Block 101.

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🌊 Why Do We Need More Than 1 Confirmation? (The Reorg Risk)

You might think that once your transaction is mined in a block (1 confirmation), the payment is complete and 100% final. However, in rare instances, a block can be discarded. This is called a Natural Chain Reorganization (Reorg).

• How it happens: Due to global propagation delays, two different miners (e.g., one in Canada and one in Japan) might solve a block at the exact same second.
• The Conflict: Half the network starts building on the Canadian block; the other half builds on the Japanese block. The blockchain has briefly split into two temporary branches!
• The Resolution: Whichever branch solves the next block first becomes the longest chain (the chain with the most accumulated Proof of Work). Under Bitcoin's rules, all nodes must automatically switch to the longest chain and discard the shorter, slower branch.
• The Result: Any transaction that was in the discarded block (but not in the winning block) is kicked back into the mempool, resetting its confirmation count back to zero!

[!NOTE] Natural chain reorganizations of 1 block depth happen roughly once every 45 days (once every ~6,500 blocks). However, reorgs of 2 blocks or deeper are extremely rare. This is why waiting for 2 confirmations makes you virtually immune to natural network reorgs!

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🚦 Recommended Confirmation Guidelines

Depending on the size and nature of the payment, you should adjust how many confirmations you wait for before delivering goods or services:

Confirmations	Risk Level	Average Wait Time	Best Used For...
0	High	Instant	Low-value retail transactions (e.g., buying a coffee or a digital book where the risk of double-spending is economically negligible).
1	Low	~10 mins	Standard, day-to-day transactions (e.g., buying a $100 jacket online).
2	Near-Zero	~20 mins	Larger, high-value transfers (e.g., buying a $2,000 computer) to protect against any natural reorgs.
6	Zero	~60 mins	Extreme transactions (e.g., purchasing a car, a house, or transferring millions of dollars). At 6 blocks, it is mathematically infeasible to reverse a transaction without a coordinated, multi-million dollar nation-state attack.
100	Immune	~16 hours	Coinbase Transactions (newly minted bitcoins rewarded to miners). The Bitcoin protocol strictly freezes newly mined coins for 100 blocks before they can be spent!