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Find Log of a Number (Logarithm Calculator)

Simple online log calculator - Use it as log base 2 calculator, log base 10, log base 'n', ln calculator (log base e) and also to find log square.

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Logarithm


You can input a number and find the log of the number for any base or Ln of the number. You can also enter the log value and find the reverse log for a given base
=

This is equivalent to writing 10 2 = 100

OR LOG10 (100) = 2

What is Logarithm?

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  • Logarithm definition:

    Logarithm is an inverse (opposite) function of exponent function.Logarithm is the power to which the number must be raised to get some other number.

    Notation:
    Logarithm is denoted by loga x = y or ay =x,
    Which is read as Logarithm of x to the base a is equal to y
    where a is the base.

  • What is Natural Logarithm?

    The natural log is nothing but the log with base 'e' and is denoted by ln

    The term 'e' is called Euler's constant and it has a value of 2.718281

  • What is Common Logarithm?

    The common log is usually log with base '10' and is denoted by log10(x)

    We can find the log of a number with any base by computing the log of number and the log of the base to base 10 log (number)/ log (base)

  • Logarithm of few numbers with different base.

    log2 8 = 3
    log5 5 = 1
    log10 100 = 2
    lne e = 1
    log7 49 = 2
    lne e2 = 2

Properties of Logorithm

User Guide icon
  • Product rule

    Multiplication of two logarithmic values is equal to the addition of their individual logorithm.
    Logb(mn) = logbm + logbn

  • Division rule

    Division of two logarithmic values is equal to the subtarction of their individual lograthmic. Logb(m/n) = logbm - logbn

  • Exponential rule

    Logarithm of x with rational exponent is equal to the exponent times its logorithm. Logbx n = nlogbx

  • Change of base rule

    Change of base rule is the steps to transform the given logorithmic expression with different valid base in quotient form. logbx = logcb / logcx

How to use the logarithmic calculator tool?

User Guide icon
  • The default configuration is log base 10 calculator or log10 calculator (or the common log)

    Enter the input value in the input field

    The log square and the log value for base 10 is automatically shown in the output fields

  • Log base 2 calculator or simply log2 calculator

    Change the base value to 2 and you can see the output reflecting the base 2 value.

  • Ln Calculator or Log Base E Calculator or the Natural Log Calculator

    To use this as ln calculator, select the base E option or enter the base E value of 2.718281 and you can compute the ln values of any input

  • Log Base Calculator to any base

    To use this with any base like Log Base 3, Log Base 4, enter the base value which is desired and it will automatically compute the log of that number

  • Reverse Log Calculator / Inverse Log Calculator

    Set the base value, enter the log value in output field, the reverse / inverse value is automatically shown in input field

How to do Log Square

User Guide icon
  • Log Square

    Log square is just the square of the respective log number.It is denoted by (log x)2 or log2x.

  • Example log2 100

    We know that log2100 = log2102
    Using product rule log xa = alogx.
    So log2102 = 2log210.
    2log210 = 2(log 10)2. Since log 10 = 1 which is equal to 2.
    So log2 100 is 2.

Reference Table for Common log and natural log

Notes:

  1. E is Eulers number or Eulers constant also known as Base E is 2.718281
  2. LN (X) = LOG OF A NUMBER 'X' to BASE E
  3. LOG (X) = LOG OF A NUMBER 'X" TO BASE 10
  4. LOG2 X = LOG OF A NUMBER 'X" to BASE 2
  5. 2 LOG X = LOG OF A NUMBER X TO THE POWER 2 to A BASE 10
  6. 3 LN X = LOG OF A NUMBER TO THE POWER OF 3 to BASE E

Term

Expansion

Base

Input

Log Result Output

Log Square

LN(10)

LN 10 Base E

2.718281

10

2.303

5.304

LN(2)

LN 2 Base E

2.718281

2

0.693

0.480

LN(1)

LN 1 Base E

2.718281

1

0

0

LN(E)

LN E Base E

2.718281

2.718281

1

1

LN 0

LN 0 Base E

2.718281

0

not defined

not defined

LOG(E)

Log E Base 10

10

2.718281

0.434

0.189

LOG10 E

Log E Base 10

10

2.718281

0.434

0.189

LOG2 E

Log 2 Base 10

10

2

0.301

0.091

LOG(10)

Log 10 Base 10

10

10

1

1

LOG(2)

Log 2 Base 10

10

2

0.301

0.091

log 0.1

Log 0.1 Base 10

10

0.1

-1

1

LOG 0.5

Log 0.5 Base 10

10

0.5

-0.301

0.091

LOG 1

Log 1 Base 10

10

1

0

0

LOG 2

Log 2 Base 10

10

2

0.301

0.091

LOG 3

Log 3 Base 10

10

3

0.477

0.228

LOG 4

Log 4 Base 10

10

4

0.602

0.362

LOG 5

Log 5 Base 10

10

5

0.699

0.489

LOG 6

Log 6 Base 10

10

6

0.778

0.606

LOG 7

Log 7 Base 10

10

7

0.845

0.714

LOG 8

Log 8 Base 10

10

8

0.903

0.816

LOG 9

Log 9 Base 10

10

9

0.954

0.911

LOG 10

Log 10 Base 10

10

10

1

1

LOG 11

Log 11 Base 10

10

11

1.041

1.084

LOG 25

Log 25 Base 10

10

25

1.398

1.954

LOG 32

Log 32 Base 10

10

32

1.505

2.265

LOG 100

Log 100 Base 10

10

100

2

4

LOG 1000

Log 1000 Base 10

10

1000

3

9

log 10000

Log 10000 Base 10

10

10000

4

16

LOG2(2)

Log 2 Base 2

2

2

1

1

LOG2(8)

Log 8 Base 2

2

8

3

9

log2 3

Log 3 Base 2

2

3

1.585

2.512

log2 5

Log 5 Base 2

2

5

2.322

5.391

2 LN 2

Log (2 to POWER 2) Base E

10

4

1.386

1.922

3 ln 5

Log 5 to POWER 3) Base E

10

125

4.828

23.313

Frequently Asked Questions on Logarithmic Calculator

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  • Only difference is with base value. Log refered to base 10. Ln refered to base e.

  • The value of e in log is equal to 2.718281.

  • Natural logarithm is the logarithm with base 'e'.Common logarithm is logarithm is with base 10.

  • No, we dont have logarithm for a negative number.More over log is function is only defined for positive numbers.

  • Log 0 is with any base is not defined and log function is defined only for values greater than 0.

  • Log of a given number is calculated by using log table by finding characterisc part and mantissa part.We need to use the respective log table to get the log value.

  • Not defined and log function is defined only for values greater than 1.

  • log 2 is equal to 0.3010

  • ln e is equals to 1.

  • log 1 is zero irrespective of any base.

  • log 10 is equals to 1.

  • log 0 is not defined and log function is defined only for all values greater than 0.

  • log 100 is equals to 2.

  • log 5 is equals to 0.6989.

  • logarithm of 4 is 0.6020.

  • log 3 is equals to 0.4771.

  • log 1000 is equals to 3.

  • log 8 is equals to 3.

  • log 6 is equals to 0.7781.

  • log base 2 3 is eqauls to 1.5849.

  • log base 2 0 is equals to 0.