Khmer has two types of vowels: Dependent Vowels and Independent Vowels.

Dependent Vowels ៖

The Chuon Nat dictionary, a classic reference for Khmer, lists 20 vowels:

Nevertheless, the modern Khmer system taught in schools lists three more vowels, raising the number to 23. These vowels are also included in the keyboard:

There are other combinations that following the same criteria (combining a vowel with the REAHMUK mark) could also be considered as vowels, but they are not considered as such by any source, so they are not included in the keyboard. They have to be written with two keystrokes. They are:

Indepentent Vowels៖

Modern Khmer has 14 independent vowels:

Reference Book:

• GUIDE FRANCO KHMER-Publication de l'institut de l'Asie du Sud-Est (J.F Sonolet and Pa Pheng)
• http://en.wikipedia.org/wiki/Khmer_language
• http://km.wikipedia.org/wiki/ភាសាខ្មែរ
• http://www.khmeros.info/download/KhmerUnicodeTyping.pdf