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Rainbow Table Size Calculator

Work out rainbow table size instantly with clear inputs, formula shown and shareable results.

About Rainbow Table Size Calculator

A rainbow table trades storage for time by storing only the endpoints of hash-reduction chains, so storage falls by the chain length while lookup cost rises proportionally. Covering all passwords up to length 8 over 62 characters means about 2.2 x 10^14 candidates — feasible in the 2000s for unsalted MD5, and completely defeated by per-password salts, which force a separate table per salt value.

Formula

Rainbow table storage

keyspace = sum of C^k for k = 1..L; chains = keyspace / chain length; storage = chains x bytes per chain

Worked example

With the default values below, Rainbow Table Size Calculator returns Storage required of 330.69 GiB. Change any input above and every figure here is recalculated in your browser.

Inputs used

Character set sizeaccepts 2–256
62
Maximum password length coveredaccepts 1–16
8
Bytes stored per chainaccepts 4–64
16
Chain length (reduction steps)minimum 10
10,000

Results

Storage required
330.69 GiB
Passwords covered
221,919,451,578,091.28
Chains to store
22,191,945,157.8091
Why salting works
A single 16-byte random salt per password multiplies this storage by the number of distinct salts, making precomputation useless

Step by step

  1. 1Values used
  2. 2Rainbow table storage
  3. 3Storage required= 355,071,122,525
  4. 4Passwords covered= 221,919,451,578,091.28
  5. 5Chains to store= 22,191,945,157.8091
  6. 6Why salting works= A single 16-byte random salt per password multiplies this storage by the number of distinct salts, making precomputation useless

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Are rainbow tables still a threat?

Only against unsalted hashes. Every modern password hash includes a random salt, which is precisely the mitigation that makes precomputed tables worthless.

How does a salt defeat precomputation?

The attacker must build a separate table per salt value. With a 128-bit salt there are 2^128 variants, so no table can be prepared in advance.

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