Looking for an online calculator? There are many web-based calculators around with different purposes and capabilities. I’ve sifted through the web to pick out some of the best calculators around. Here goes:

General Calculators

This section lists calculators which offer general calculation capabilities. These allow you to simply type any calculation into a free-form text box which they then try to answer.

Calcatraz – My free online calculator offering scientific, unit and currency calculations. Shows workings and a history of previous calculations.

CalculateForFree multiple functions – A calculator script with many functions. This calculator includes different measures conversion, rule of three, temperature conversion and other formulas.

Google calculator – Google will provide answers to calculations entered into the main search box.

Instacalc - The fast, easy shareable online calculator.

Wolfram|alpha – A computational knowledge engine. Enter a query and it uses its built-in algorithms and a growing collection of data to compute the answer.

Task-Specific Calculators

This section is for calculators which provide one specific function (e.g. scientific calculator, tax calculator, etc).

CalculateForFree -Free calculators for home, work and school. The main page offers a basic calculator with links to a wide range of specific calculators including travel, poker odds and global warming calculators.

Calculator.com – Another site with a number of specific calculators, including mortgage, math, loan, finance, scientific, health & sports calculators.

CalculatorSoup - As with the previous two, Calculator Soup offers a range of calculators for specific calculations, such as algebraic and geometric calculations.

Calculator.net – Claiming to be the richest collection of free online calculators, it offers a large number of specific calculators including mortgage and loan calculators and a number sequence calculator.

Math.com – A collection of specific calculators including trigonometry, probability and finance calculators.

List of Online Calculator Lists

Looking for something not on this list? Here are some other great lists of web-based calculators (I’ll be adding to this as I come across new lists):

Numa - A list of calculators for traders looking to price options, etc.

List of Online Graphing and Scientific Calculators - The title says it all really – if you’re after a graphical calculator, this could be a good place to start.

Top 10 Online Calculator Directories – This is getting a bit meta now – as this is itself a list of online calculator lists, it should really be in its own list. Oh well!

Well that’s it for now! If you know of a web-based calculator which isn’t on this list, but should be, please let me know in the comments.

The fast, easy and shareable online calculator.