Drill Symbols

Now reading version 17.1. For the latest, read: Drill Symbols for version 21

The Drill Symbols Dialog.


A standard element required for the manufacture of a Printed Circuit Board is a drill drawing table, also known as a drill table or a drill drawing legend. The drill table lists the size and number of holes for each drill used on the board. Each drill size can be represented by a symbol, a letter, or the actual hole size. The Drill Table is configured in the Drill Table dialog, with the assignment of symbols / letters to hole sizes being performed here.


The drill symbols are always configured in the Drill Symbols dialog and the assignments remain consistent for a PCB. The dialog can be configured from a variety of places; generally you will find access to it where you need it.

Specifically, the Drill Symbols dialog can be accessed via:

  • The Drill Drawing layer tab in the right-click menu. Select Configure Drill Symbols.
  • The Drill Table dialog, click the Configure Drill Symbols button.
  • The PCB panel, Hole Size Editor mode, hole size list region of the panel. Right-click and select Configure Drill Symbols from the menu.
  • The Layer Properties dialog, click the Configure Drill Symbols button. The Layer Properties dialog is accessed by editing the Drill Drawing layer in the PCB Printout Properties dialog, or from the PCB Printout Settings page of the Smart PDF Wizard.
  • The Drill Drawing tab of the Gerber Setup dialog, click the Configure Drill Symbols button.


Grid Area

The grid area displays detailed information about the mapping of a symbol to a hole size. It can be customized, including:

  • Change the column order - Click on and drag a column header to change the order of columns.
  • Show/Hide a column - Right-click on a column header and enable/disable the checkbox for the column.

To sort the drill symbols, click once on a column heading to sort by that column. A small triangle will appear, indicating the current sort direction - click a second time to reverse the sort direction. 


Click the Grouping button to set which properties are to be used to control the assignment of symbol-to-drill events (holes). Holes are clustered initially by hole size and then assigned separate symbols whenever a grouping option that uniquely identifies them is enabled. For example, the design could include a round pad with a 1mm hole, and another square pad with a 1mm hole - if Pad Shape is not enabled in Grouping, then they will be assigned the same symbol. But if Pad Shape is enabled in Grouping then they will be assigned separate symbols.

Graphic Symbol

Each hole site can be represented by a symbol, a letter, or a string showing the actual hole size. These options control the symbol style and size:

  • Symbol - Use a symbol at each hole site. The software includes 15 pre-defined symbol styles, as shown in the image below. If there are more than 15 hole sizes then alpha characters will automatically start to be used.
  • Character - Use an Alpha character at each hole site.
  • Symbol Size - Height of the symbol/letter displayed on the Drill Drawing layer. Note that this setting applies to all of the symbols/letters used on the drill drawing.

Draw Symbols

These options control the style of drill symbol and when they should be shown:

  • Show Symbols - Show a symbol at each hole site.
  • Show Hole Size - Show the actual drill size at each hole site as a numerical value.
  • Show Drill Symbols - The default behavior is to not show drill symbols on the Drill Drawing layer. Enable this option to display the drill symbols.

Available Symbols

There is a total of 15 symbols available, as shown below. If there are more than 15 different hole sizes in the PCB then letters are automatically assigned.

Default drill symbols available in the software.


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The features available depend on your Altium product access level. If you don’t see a discussed feature in your software, contact Altium Sales to find out more.