Among other useful things (e.g. typing phonemic symbols without having IPA fonts installed on your device), PhoTransEdit provides Text2Phonetics, which converts English texts up to 300 characters into phonetic transcriptions in the International Phonetic Alphabet, letting you choose between Received Pronunciation (RP) and General American (GA).
This phonemic chart uses symbols from the International Phonetic Alphabet (IPA). IPA symbols are useful for learning pronunciation. The symbols on this chart represent the 44 sounds used in British English speech (Received Pronunciation or RP, an educated accent associated with but not exclusive to south-east England).