Skip to main content

Interactive Logarithm Table

Before calculators, the best way to do arithmetic with large (or small) numbers was using log tables.

Invented in the early 1600s century by John Napier, log tables were a crucial tool for every mathematician for over 350 years.

First, let's find some log values and see what they mean when re-expressed in index notation.

Find the log of a number

Your calculator has only base 10 or base `e` logarithms. The following section allows you find the log of whatever number you like, for some common bases.

Log Values, Different Bases

decimal places

The logarithm of (base ) is .

That is:

In index notation, the above log equation means the same as:

The above calculator is using the Change of Base formula that we met earlier.

Interactive Log Table

In this next section, you can create different sized log tables, with different bases.

By exploring the values given in the tables, you can better understand how logs work. For example, when the base is 2, the log of 8 is 3.0000. This is simply because `2^3=8`. Logarithms are just index expressions written sideways, after all.

Table of Log Values

decimal places

Log Table: Base 2

Further Reading

You may also be interested in:


Search IntMath, blog and Forum

Search IntMath

Online Math Solver

This math solver can solve a wide range of math problems.

Math Lessons on DVD

Math videos by

Easy to understand math lessons on DVD. See samples before you commit.

More info: Math videos

The IntMath Newsletter

Sign up for the free IntMath Newsletter. Get math study tips, information, news and updates each fortnight. Join thousands of satisfied students, teachers and parents!

See the Interactive Mathematics spam guarantee.