Calculyn

Logarithm Calculator

Calculate the logarithm of any positive number in any base, plus natural log and log base 2.

Results update as you type.

log base 10 of 100

2
Natural log (ln)
4.60517
Log base 10
2
Log base 2
6.643856
log base 10 of 1002

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Quick answer

log base 10 of 100 is 2; ln(100) ≈ 4.605170; log base 2 of 100 ≈ 6.643856.

How it works

A logarithm answers: what power do I raise the base to, to get this number? log₁₀(100) = 2 because 10² = 100.

Formula

log_b(x) = ln(x) ÷ ln(b)

Assumptions & limitations

  • Results are rounded for display.

Frequently asked questions

Why can't I take the log of 0 or a negative?

No power of a positive base ever gives 0 or a negative number, so the log isn't defined there.