Count sheets in Excel whether visible or hidden, a window will popup showing the count of visible and hidden worksheets in the current workbook. Dose for Excel's Sheets utility can easily count worksheets in current workbook with one click.
1. Click DOSE » Sheets.
2. A window will pop up shows the count of visible worksheets and count of hidden worksheets in the current opened workbook. In below example, sheet2, sheet3 are hidden. See screenshots: