Calibri Sans Serif Font is a sans-serif typeface family designed by Luc(as) de Groot in 2002–2004 and released to the general public in 2007, with Microsoft Office 2007 and Windows Vista. In Office 2007, it replaced Times New Roman as the default typeface in Word and replaced Arial as the default in PowerPoint, Excel, Outlook, and WordPad. De Groot described its subtly rounded design as having “a warm and soft character”.

Calibri is part of the Clear Type Font Collection, a suite of fonts from various designers released with Windows Vista. All start with the letter C to reflect that they were designed to work well with Microsoft’s Clear Type text rendering system, a text rendering engine designed to make text clearer to read on liquid-crystal display monitors. The other fonts in the same group are Cambria, Candara, Consolas, Constantia and Corbel.