Hash Collision Probability Calculator
Calculate hash collision probability using birthday paradox. Find collision probability and birthday bound for hash functions.
Inputs
bits
Results
Collision Probability
0%
Expected Collisions
0
Birthday Bound
400,651,869,298,001,200,000,000,000,000,000,000,000
Time to Collision0 days
Collision Probability
0%
Expected Collisions
0
Birthday Bound
400,651,869,298,001,200,000,000,000,000,000,000,000
How to Use This Calculator
- Start by filling in the input fields below. Results update instantly as you type, so you can experiment with different values to see how they affect the outcome.
- Hash Length — Hash output length in bits Accepts values from 64 bits to 512 bits (default: 256 bits).
- Number of Hashes — Number of hash values to compare Accepts values from 1 to 1,000,000,000,000,000 (default: 1,000,000).
- Hash Function — Hash function type Choose from: SHA-256 (256 bits), MD5 (128 bits), SHA-1 (160 bits). default: 0.
- Once all inputs are set, review your results in the Results panel. Here's what each output means:
- Collision Probability — shown as a percentage. This is the primary result of this calculator.
- Expected Collisions — shown as a numeric value. This is the primary result of this calculator.
- Birthday Bound — shown as a numeric value. This is the primary result of this calculator.
- Time to Collision — shown as a numeric value.
- Explore the related calculators below if you need deeper analysis or want to approach this topic from a different angle.
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Formula
P(collision) ≈ 1 - e^(-n²/(2×m))Related Calculators
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