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Mathematics

Logarithm Calculator

Variable Legend

b= basex= argument (must be > 0)y= logarithm valueln= natural log (base e ≈ 2.718)lg= common log (base 10)

Definition

Inverse of exponentiation.

Log rules

Fundamental identities for manipulating logarithms.

Product
Quotient
Power

Change of base

Convert between any two bases.

Special values

log_b(1)
log_b(b)
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Pro Tip

Always verify your input values before calculating. For logarithm, small input errors can compound and significantly affect the final result.

Difficulty:Intermediate

Did you know?

A 9.0 earthquake releases about 31 times the energy of an 8.0, because the Richter scale is logarithmic (base 10). Each whole number represents 10× more ground motion.

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Reviewed May 2026
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