How Many Qubits to Break Bitcoin? The Real Quantum Threat in 2026

How many qubits to break Bitcoin? A 2022 University of Sussex study estimated roughly 13 million physical qubits to crack Bitcoin's ECDSA signatures in about a day, or 300 million for an hour-long attack. With IBM's Condor processor reaching just 1,121 physical qubits in 2023, the threat remains theoretical—but the 'harvest now, decrypt later' risk means exposure begins long before 'Q-Day'. This guide explains the numbers, separates hype from reality, and outlines practical steps for holders.

Part of the BMIC quantum series. For the full background — the threat, the NIST standards and the buying checklist — start with the quantum crypto presale guide.

5 steps to judge any 'qubits to break Bitcoin' headline

1. Understand the qubit gapToday's 1,121-qubit IBM Condor is millions short of the 13M+ needed for a cryptographically relevant attack.
2. Distinguish physical vs logical qubitsError correction multiplies the physical qubits needed; the Sussex study counts physical qubits directly.
3. Prioritize signature protectionECDSA and Ed25519 signatures are vulnerable; SHA-256 mining hashes face far less quantum risk.
4. Avoid reused addressesSpent-from addresses expose public keys; fresh addresses retain an extra hash layer of protection.
5. Evaluate post-quantum optionsNIST-standard algorithms like CRYSTALS-Kyber (key encapsulation) resist Shor's algorithm attacks.

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Why 13 million qubits? The Bitcoin attack math

The 2022 University of Sussex study modeled a fault-tolerant quantum computer running Shor's algorithm against Bitcoin's ECDSA signatures. Their estimates—13 million physical qubits for a day or 300 million for an hour—account for the error correction overhead needed to keep qubits stable during computation. Unlike 'logical qubit' counts that abstract this overhead, these figures reflect real hardware requirements. For context, IBM's 2023 Condor processor had 1,121 physical qubits with high error rates. Grover's algorithm poses less risk: it only halves symmetric security, so SHA-256's 256-bit strength drops to ~128 bits—still impractical to brute-force. The immediate concern is 'harvest now, decrypt later' attacks recording exposed public keys today for future decryption.

What crypto holders should verify

No quantum computer exists today that can break ECDSA or Ed25519 signatures. However, the timeline is uncertain—estimates range from a decade to never. Projects using NIST-standard post-quantum cryptography like CRYSTALS-Kyber (FIPS-203 for key encapsulation) or CRYSTALS-Dilithium (FIPS-204 for signatures) mitigate this risk. Bitcoin, Ethereum (ECDSA), and Solana (Ed25519) remain vulnerable in their current forms. XRP supports both ECDSA and Ed25519 but lacks post-quantum upgrades. Until networks migrate, users should avoid address reuse and consider wallets with quantum-resistant features. Presale projects like BMIC integrate NIST-standard post-quantum cryptography, while others like Solaxy and Best Wallet still rely on classical signatures.

How BMIC compares to other presales

Prices and security architectures below are as published on the best crypto presale ranking. Price alone tells you little — the security column is the part most buyers skip.

How to buy

To purchase BMIC, visit the presale page and connect MetaMask for ETH payment or use a card (no crypto needed). Tokens are claimable after the TGE at the presale price of $0.0528542. The Ethereum contract (0xf365...) is publicly verifiable. Card payments are accepted at the presale checkout — no crypto needed to get started (ETH via MetaMask also works), and the quantum-resistant wallet comes free with your purchase.