Logarithm Calculator
Fill in the values and the answer updates as you type.
How the Logarithm Calculator works
log_b(x) is the power you raise b to in order to get x. Example: log₁₀(1000) = 3 because 10³ = 1000. Any base can be computed with the change-of-base rule: log_b(x) = ln(x) ÷ ln(b). The number must be positive and the base cannot be 1.
Inputs and results
The Logarithm Calculator takes 2 inputs and gives 4 results.
What you enter
- Number — starts at 1000.
- Base — starts at 10.
What you get
- Logarithm in your base
- Natural log (ln)
- Log base 10
- Log base 2
Example: Logarithm Calculator with the starting values
With number 1000 and base 10, the calculator returns:
| Logarithm in your base | 3 |
|---|---|
| Natural log (ln) | 6.9078 |
| Log base 10 | 3 |
| Log base 2 | 9.9658 |
Change any value above and the results update straight away.
Logarithm Calculator FAQ
How do I use the Logarithm Calculator?
Enter number and base in the fields, then read logarithm in your base, natural log (ln), log base 10 and log base 2 in the result panel. The answer updates as you type, and you can press Calculate or Enter to refresh it. Use “Copy link” to share your exact numbers with someone else.
What does the Logarithm Calculator calculate?
Log of any number in any base, plus ln, log10, and log2. It returns logarithm in your base, natural log (ln), log base 10 and log base 2 from the 2 values you provide.
What values does the Logarithm Calculator start with?
It opens with number 1000 and base 10 so you can see a working result straight away. Replace them with your own numbers, or press Reset to return to these starting values.
Is the Logarithm Calculator free and private?
Yes. It is free, needs no account, and runs in your browser, so nothing you type is sent to or stored on our servers. See the Privacy Policy for details.
Can I rely on the Logarithm Calculator for important decisions?
Treat the result as a well-rounded estimate. Real situations often have details a general calculator cannot know, so confirm important decisions with a qualified professional. See the Disclaimer for more.