Need to know what drill bit to use to tap a hole for a screw or bolt? Or maybe you just want to drill a thru hole for one. TapDrillTool Free make is REALLY easy to find out. No tables to scroll through, no screw selection pages - just dial in the screw size, pitch and desired engagement percentage and your options are displayed instantly. You'll see the optimal hole size and the bits that come closest to your request, along with the resulting engagements and hole size errors. Features include: - Inch screw threads from #000 thru 1-7/8" - Metric screw threads from M1 thru M56 - Engagement from 50% thru 80% or Thru Hole - Works for both cutting (most common) and forming taps. - Results for Letter, Number and Fractional drill bits. (Press the Tap Type button to select a different one.) If you like TapDrillTool Free you may want to consider buying the paid version, which has the following additional features: - No ads - Optional drill oversize compensation - Saves state and settings on exit