Google Translate converts English to Spanish for free using voice or keyboard input. SpanishDict.com and SpanishCentral.com also provide free English to Spanish conversion through text only.
You can convert English into Spanish with Google Translate by selecting each language over a text box and then clicking the keyboard or the microphone icon for text or voice. Once you type or speak the English passage to enter it into the left box, the application shows the Spanish translation in the right box. Clicking on the audio icon in the box to the right plays an audio example of your translated sentence.
Entering text into the box on the front page of SpanishDict.com and clicking on Translate returns both full and word-by-word translations. SpanishCentral.com has a similar text box interface, but it offers only direct translation.