Reformatting a previously formatted portion of document text using a "live preview" technique. A sample of formats from a format set may be determined. A previously formatted portion of text within the document may be identified, for example, by identifying the portion of text positioned immediately adjacent to a cursor or by identifying a highlighted portion of text. For each format included in the sample of formats, the portion of text may be reformatted and displayed in a live preview window. The live preview window may be a floating window that hovers above the document. A custom format, such as a user-defined format may be added to the sample of formats. In response to adding the custom format to the sample of formats, the portion of text may be reformatted with the custom format and displayed along with the rest of the live preview text in the live preview window. Accordingly, the user may view and compare the portion of text formatted in a variety of formats from the format set and/or custom formats, prior to actually reformatting the portion of text in the document.