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Calcimator

RSA Key Strength Calculator

Calculate RSA key strength, equivalent symmetric key length, brute force time, and security margins.

Inputs

bits

Results

Security Level

112 bits

Equivalent Symmetric Key

112 bits

Brute Force Time

164,500,000,000,000 years

ECC Equivalent Key Length224 bits
Key Space2,048 bits
How to Use This Calculator
  1. Enter the RSA key size in bits (1024, 2048, 3072, 4096).
  2. Set the attacker factoring compute budget (current hardware or projected future).
  3. Review the equivalent symmetric security level in bits.
  4. Verify that 2048-bit keys provide about 112-bit security -- the current NIST minimum for new systems.
  5. Plan migration to 3072+ bits by 2030 per NIST SP 800-131A recommendations.

How the result changes with Key Length

Key LengthSecurity LevelEquivalent Symmetric KeyBrute Force Time
2,099112.8 bits112.8 bits285,900,000,000,000 years
6,067168.6 bits168.6 bits17,930,000,000,000,000,000,000,000,000,000 years
10,829218.2 bits218.2 bits15,780,000,000,000,000,000,000,000,000,000,000,000,000,000,000 years
14,797251.3 bits251.3 bits142,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 years

What each input means

Key Length
RSA key length in bits
Algorithm
Cryptographic algorithm

How this is calculated

Formula

Security level per NIST SP 800-57 lookup (e.g., RSA-2048 ≈ 112-bit security)

Worked example, using the default values

  1. Identify Input Parameters
    Key Length = 2048, Algorithm = 0 = 2 input(s) provided
  2. Calculate Security Level
    Security Level
    112 = 112
  3. Calculate Equivalent Symmetric Key
    Equivalent Symmetric Key
    112 = 112
  4. Calculate Brute Force Time
    Brute Force Time = Number.isFinite(bruteForceTimeYears)
    164500000000000 = 164500000000000
  5. Calculate ECC Equivalent Key Length
    ECC Equivalent Key Length
    224 = 224
  6. Calculate Key Space
    Key Space
    2048 = 2048

Engine last updated . Checked against 1 independently-derived test — how we verify calculators.

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