What percent of Bitcoin is quantum exposed?
Roughly 25-30% of circulating supply sits in addresses that have already published their public keys on-chain (P2PK coinbase outputs, P2TR, or any reused / spent-from P2PKH/P2WPKH). That share would be the first to fall to a cryptographically relevant quantum computer.
There are three contributing buckets. First, the ~1.7M BTC mined to P2PK outputs in the first ~16 months — public keys are in the output script itself. Second, every P2PKH/P2WPKH address that has ever spent — the spending transaction broadcasts the public key. Third, all Taproot (P2TR) outputs by construction.
The exact percentage drifts as the chain grows and as funds move. Independent estimates from chain-analysis firms put the exposed share in the 25-30% band as of 2025, with the long-dormant Satoshi-era P2PK supply being the largest single concentration.
The remainder — roughly 70-75% — sits in never-spent P2PKH/P2WPKH addresses and is quantum-safe against today's cryptanalysis assumptions until those addresses spend.
Related questions
Why is this percentage not zero?
Because P2PK outputs in early blocks publish the key directly, and because address reuse and spend behavior are common. Every Bitcoin transaction that signs from an address reveals that address's public key forever — there is no way to un-reveal it.
Is the percentage growing or shrinking?
Net growing, slowly. Taproot adoption adds to the exposed bucket on every Taproot receive. P2PKH/P2WPKH spending also adds. The only force pushing the percentage down is fresh mining to never-spent addresses, which is a small flow relative to existing supply.