Quote from: vapourminer on July 20, 2025, 09:23:27 PM

possibly easy to calculate (?) but im far too lazy

The calculation itself isn't that difficult. But you need to,
1. Find total of UTXO with exposed public key.
2. Determine or assume how people move their vulnerable UTXO. This will affect estimation of TX will be created.
3. Know size of each UTXO types and size of new QC resistant address.

Here's my calculation with many naive assumption.

1. I assume it means 25% of total UTXO with exposed public key.

Quote from: https://github.com/jlopp/bips/blob/quantum_migration/bip-post-quantum-migration.mediawiki

Roughly 25% of all bitcoin have revealed a public key on-chain; those UTXOs could be stolen with sufficient quantum power.

2. https://statoshi.info/d/000000009/unspent-transaction-output-set says currently there are about 167 million UTXO. So i assume there's 41.75 million vulnerable UTXO.
3. I assume each TX will contain 10 vulnerable UTXO and 1 QC resistant address.
4. For average size of each TX for migration purpose, i'll naively calculate average of 3 kinds of TX.

Quote from: https://bitcoinops.org/en/tools/calc-size/

Code:

Average TX size = (1524 + 721.5 + 628.5) / 3 = 958 vbytes

Based on those, here's the calculation.

Code:

Total transaction = 41750000 UTXO / 10 UTXO (in single TX) = 4175000 TX (4.175 million TX)
Total transaction size = 4175000 TX * 958 vbytes = 3999650000 vbytes
Total blocks needed = 3999650000 vbytes / 1000000 vbytes (block size limit) = 3999.65 blocks (rounded to 4000 blocks)
Total time = 4000 blocks / 144 blocks (total blocks in one day) = 27.77... days

27.7 days is very long time, so you better hope majority people won't move their vulnerable UTXO at similar time.

Quote from: Mary319Horne on Today at 05:21:12 AM

Recent reports indicate roughly 25% of Bitcoin's supply, about 4 million BTC, is in quantum-vulnerable addresses. To move these funds to new quantum-resistant addresses would require an estimated 4 million transactions. Given an average transaction size of 225 bytes and realistic Bitcoin block sizes of 2 MB, this would fill approximately 450 blocks. This volume of transactions, if executed rapidly, would cause severe chain congestion for over three days, leading to significantly increased fees and network slowdowns, which is why developers are proposing a phased migration.

FWIW, there are times when Bitcoin network congested (as in block always full and people had to pay higher fee rate) far longer than 3 days.