Mr Calcu | Easily solve logs with any base—fast, accurate, and beginner-friendly.

Calculate and convert logarithms effortlessly. Master any base with ease using this intuitive tool—explore your math potential and verify results fast.

Logarithm Calculator

Logarithm Calculator Guidelines

You're just a few steps away from mastering logarithms!

How to Use the Logarithm Calculator

  • Enter a positive real number for the value of x (x > 0).
  • Select or enter a base greater than 0 and not equal to 1.
  • Use base 10 (log), base e (ln), or custom bases.
  • The calculator automatically applies the change of base formula for custom bases.
  • Results are rounded to 3 decimal places by default.
  • Warnings are shown if input values are invalid (e.g., base ≤ 0, x ≤ 0).

Logarithm Calculator Description

What Is a Logarithm?

A logarithm answers the question: "To what power must a base number be raised to obtain a given value?"

  • Example: log2(8) = 3 because 23 = 8
  • General Form:
    logb(x) = y ⟺ b^y = x
  • Logarithms are the inverse of exponentiation.

Change of Base Formula

Most calculators support only log base 10 (log) or base e (ln). To compute logarithms of other bases, use:

logb(x) = logc(x) / logc(b)
  • Common bases: 10 and e (≈ 2.718)
  • Useful in: algorithm design, signal processing, compound interest calculations

Derivation

logb(x) = y ⟺ b^y = x
logc(b^y) = logc(x)
y * logc(b) = logc(x)
y = logc(x) / logc(b)

Edge Case Explanations

  • log10(1) = 0: Any number raised to 0 is 1
  • logb(b) = 1: The base raised to 1 equals itself
  • logb(x) where x < 0: Undefined in the real number system
  • logb(0): Undefined; as x → 0⁺, log(x) → -∞
  • log1(x): Undefined; base must not equal 1

Real-World Case Studies

1. Finance – Compound Interest

If your investment doubles every 10 years, to grow 8x:

log2(8) = 3 → 3 × 10 = 30 years

2. Computer Science – Binary Search

To search 1024 items using binary search:

log2(1024) = 10 → 10 comparisons max

Try the calculator now and turn complex logs into clear answers in seconds!

Example Calculation

InputBaseResultExplanation
100102102 = 100
82323 = 8
1000e6.908e6.908 ≈ 1000
150Any base raised to 0 equals 1
2562828 = 256
010Undefinedlog10(0) is undefined (approaches -∞)
-52Undefinedlogarithms of negative numbers are undefined in real numbers
101UndefinedBase 1 makes the function degenerate (1^x = 1)

Frequently Asked Questions

A logarithm is the power to which a base is raised to produce a given number.

Use the formula: log<sub>b</sub>(x) = log<sub>c</sub>(x) / log<sub>c</sub>(b).

Yes, it can calculate logarithms with any base.

Because no power of a positive base can result in zero. As x approaches zero from the positive side, log(x) approaches negative infinity.

The base must be positive and ≠ 1. Bases ≤ 0 or = 1 do not yield meaningful logarithms in real numbers.

Not in the real number system. The logarithm of a negative number is a complex number.

log usually refers to base 10 (common log), while ln refers to base e (natural log, where e ≈ 2.718).

Use logarithmic rules such as the product, quotient, and power rules to break down or combine terms.

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