Do a logarithm calculation by hand check
Common, natural, and arbitrary-base logarithms plus antilogs — the pocket check for decibels, pH, and exponential growth work.
Tools used in this guide
The job
Decibel math, pH, half-lives, and growth rates all reduce to logarithms. The tool evaluates log and antilog in any base so a calculator-app answer can be checked against the formula by hand.
Pick the base
Fill any two of base, argument, and result — leave the one to solve empty. Quick-base buttons set b to e, 10, or 2. The result echoes all three values plus the argument's ln, log₁₀, and log₂ for cross-checking.
- log₁₀(1000) = 3 — each power of ten is one unit.
- The ln / log₁₀ / log₂ rows show the same argument in other bases, a quick sanity check.
Worked example
pH 4.5 means [H⁺] = 10^-4.5 ≈ 3.16×10⁻⁵ M. Enter base 10, argument 10^-4.5 to invert, or compute -log₁₀(3.16e-5) to go the other way.
Where it stops
It solves one log_b(x) = y relation — not general equations, log-expression expansion, or complex numbers. Inputs are limited to magnitudes below 1e300; arguments must be positive and bases positive and ≠ 1.