Negative Log Calculator (-log)

Your details

Base 10 is used for pH and common scientific logarithms. Base e is the natural logarithm. Base 2 is used in information theory. Choose "Custom" to enter any base.
Must be a positive number (x > 0). For pH, enter the hydrogen ion concentration in mol/L.
Number of decimal places shown in the result.
Negative logPositive result (x < 1)
3

-log_b(x)

log_b(x)-3
log_b(1/x)3
Inverse: b^(-result)1,000
3
Negative (x > 1)<0Low positive0-3Mid range3-7High positive7+

-log_base 10(0.001) = 3.0000

  • pH = 3.0000: if x is a hydrogen-ion concentration in mol/L, this solution is acidic.
  • -log10(0.001) = 3.0000, equivalent to log10(1/0.001) = 3.0000.
  • Identity check: -log_b(x) = log_b(1/x), so log_b(1/0.001) also equals 3.0000.
  • Because x = 0.001 is less than 1, the negative log is positive.

Next stepFor pH, also check the pOH = 14 - pH relationship to find hydroxide-ion concentration.

 = Powered by OnlyCalculators