Estimate collision probability and birthday-bound sample thresholds for an ideal hash output of a chosen bit length.
How it works
The calculator uses the birthday approximation for an ideal uniformly distributed n-bit hash. With k samples, λ = k(k−1)/(2×2^n) and collision probability is approximately 1−e^(−λ).
The formula
n is hash-output bits, k is the number of samples, λ is expected colliding-pair intensity. Collision security is shown as n/2 bits for an ideal hash.
Worked example
For a 256-bit ideal hash, the 50% birthday threshold is about 4.0×10^38 samples, illustrating why collision strength is roughly 128 bits rather than 256.
For educational and technical analysis only. Not financial advice, wallet software, transaction signing, or a security audit. Protocol and wallet behavior can differ. Never enter a seed phrase, private key, xprv or wallet password into He-Sab or any website.
Frequently asked questions
What does this calculator calculate?
Estimate collision probability and birthday-bound sample thresholds for an ideal hash output of a chosen bit length.
Should I enter a seed phrase, private key, xprv or wallet password?
No. These calculators do not need secret wallet material. Never paste a seed phrase, private key, xprv or wallet password into He-Sab or any website.
Is the result authoritative for moving real funds?
No. It is an educational technical estimate. Confirm results with current Bitcoin or Lightning software, specifications and a safe test environment before using real funds.