Fastest way to type greek letters like α or β?

Solution with Autohotkey

To use Autohotkey is probably the fastest solution. It works globally in all Windows programs. You need this Autohotkey script: greekletters.ahk, it works like this:

After installing the script you simply activate ⇪ Capslock, then you type for instance the key a which turns immediately into α. As fast as it can be.

To get capitalized letters, activate ⇪ Capslock, then hold Shift and press the letter you need.

Solution with Google Docs

Máté Juhász gave a great answer, which works if you have installed Microsoft Word 2007 or higher.

For everybody who has not Microsoft Word available, you can use Google Docs as a workaround. There you specify the Automatic corrections, go to >Tools >Preferences then insert for instance:

The same autoreplacement I can do now with Notepad++ using the Fingertext plugin.

So "Autocorrect" (automatic replacements) is the way to go!

Thanks to all for your ideas.

In Microsoft Office you can add auto correct list items, e.g. to automatically replace (alfa) to α, so after typing the text it will be automatically replaced to the character. It's longer to type then Alt codes, but also easier to remember.

Update

Doing a bit of research I've realized that this solution is already implemented, you don't need to type again the whole alphabet, here you can find how it works in Word (from version 2007): https://support.office.com/en-za/article/Math-AutoCorrect-symbols-b8b463d9-f47d-45c4-a00f-9245c2b38843.
And way to get it working in other Office programs too: http://answers.microsoft.com/en-us/office/wiki/office_2013_release-excel/how-to-use-math-autocorrect-in-excel/dadf030c-2ba3-4080-9383-3050705792cf