Chrome
In Elements > Styles pane, hover over the selector name to see the specificity in a tooltip.
Safari
Inspect element > In the Styles pane, hover over the selector to reveal a tooltip displaying the specificity of that selector.
Polypane
Inspect element (
Cmd+Shift+C
orCtrl+Shift+C
) > In the Style pane, the specificity is shown adjacent to the selector under the file name.Click the specificity to open the CSS Specificity calculator in the Browse panel.