How it works
A logarithm asks "what power do I raise the base to, to get this number?" — the inverse of exponentiation. Antilog goes the other way: given the power, it returns the number.
logbase(x) = y ⇔ basey = x
logbase(x) = ln(x) ÷ ln(base) — computed via the natural log, any base
Worked example
log base 10 of 1,000.
- Ask: 10 raised to what power gives 1,000? 10³ = 1,000.
log₁₀(1000) = 3.
Common questions
What's the difference between log and ln?
"log" (without a subscript) usually means base 10; "ln" means the natural log, base e (≈2.71828). Both are logarithms, just with a different base — select whichever this calculator's base chips match.
Why can't I take the log of a negative number or zero?
No real power of a positive base ever produces zero or a negative number, so there's no real answer — the calculator flags this as undefined rather than showing an incorrect value.
What is antilog used for?
It reverses a logarithm — useful when you know an exponent (say, from a pH or decibel calculation) and need the underlying quantity it represents.