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How-to guide

How to Calculate Logarithm: Formula, Steps & Examples

Learn how to calculate Logarithm — the formula explained step by step, with worked examples and a free calculator to check your answer.

By Vikram Iyer, M.Sc Mathematics · Updated Jun 2026 · 2 min read

Calculating your logarithm (log_base of number) is straightforward once you know the Logarithm formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the Logarithm Calculator.

What is Logarithm?

The Logarithm calculation tells you your logarithm (log_base of number) from a few simple inputs. The figure you are solving for here is the logarithm (log_base of number).

The Logarithm formula

This calculation combines several inputs through a multi-step method rather than a single one-line formula. Enter the values below and the calculator resolves each step in order. The inputs it needs are:

  • Number — a number. Example: 1,000.
  • Base — a number. Example: 10.

How to calculate it step by step

  • Write down the number (for example, 1,000).
  • Write down the base (for example, 10).
  • Apply the formula above to get your logarithm (log_base of number).
  • Double-check the result with the Logarithm Calculator.

Worked examples

Example 1

Input / OutputValue
Number1,000
Base10
Logarithm (log_base of number)3.000000
Natural log (ln)6.907755
Log base 103.000000

With number of 1,000 and base of 10, the logarithm (log_base of number) works out to 3.000000.

Example 2

With number of 2,000 and base of 10, the logarithm (log_base of number) works out to 3.301030.

ResultValue
Logarithm (log_base of number)3.301030
Natural log (ln)7.600902
Log base 103.301030

Example 3

With number of 500 and base of 10, the logarithm (log_base of number) works out to 2.698970.

ResultValue
Logarithm (log_base of number)2.698970
Natural log (ln)6.214608
Log base 102.698970

Tips for an accurate result

  • Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
  • Round only at the very end. Rounding inputs early can shift the final answer noticeably.
  • Re-run the numbers whenever an input changes, rather than estimating from an old result.

Prefer not to do the maths by hand? — the Logarithm Calculator does it instantly, for free, with the formula and a worked example built in.

Continue exploring math calculators with these tools: Margin of Error Calculator, Sample Size Calculator, Confidence Interval Calculator, Coefficient of Variation Calculator, Regular Heptagon Area Calculator.

Calculators in this guide

Frequently asked questions

Gather each input, apply the formula step by step keeping your units consistent, and round only at the end. You can verify your answer instantly with the Logarithm Calculator.

It uses the standard formula with exact arithmetic, so the result is correct for the inputs you enter. Bear in mind that real-world outcomes can still differ when underlying assumptions change.

Vikram Iyer · M.Sc Mathematics

Vikram Iyer is a mathematics educator with over fifteen years of teaching experience, specialising in making quantitative concepts clear and practical for everyday use.