To determine how many data points went into the interpolation of each node in a Surfer grid: 

1. Click Home | Grid Data | Grid Data.
2. In the Grid Data - Select Data dialog,
   1. In the Gridding Method pane on the left, choose Data Metrics.
   2. On the right, choose the data file you used to create your original grid from the Dataset 1 dropdown list or by clicking the Browse button, selecting it, and clicking Open.
   3. Verify the X, Y, and Z data columns are set to the same columns as the original grid file used.
   4. If you applied any data filters to the original grid, click the Filter Data button and set up the same filter for this grid.
   5. Click Next.
      

3. In the Grid Data - Data Metrics - Options dialog,
   1. In the Data Metrics Parameters section on the right, set the Metric to interpolate to Count.
   2. In the Search Neighborhood section, set the same search parameters that you used to create the original grid file.
   3. Click Skip to End.
   4. Verify the Output Grid Geometry, and Grid Z Limits sections are all the same as what was set for the original grid.
   5. Click Finish to create the grid. 

The Z value of each node is the number of points in the search ellipse (i.e. the number of points that went into the interpolation of that grid node in the original grid). You can create a map of this file or use the Grids | Edit | Convert command to convert it to a DAT for opening in a text editor.

To determine how many data points went into the interpolation of each node in a Surfer grid in Surfer 16 and older: 

1. Click Home | Grid Data | Grid Data.
2. Choose the data file used to create your grid and click Open.
3. In the Grid Data dialog, change the Gridding Method to Data Metrics.
4. Click the Advanced Options button.
5. On the General page, expand Data Location Statistics and click Count.
6. On the Search page, set the same search parameters that you used to create the original grid file.
7. Click OK.
8. If you applied any data filters to the original grid, click the Filter Data button and set up the same filter for this grid.
9. Verify the Data Columns, Grid Line Geometry, and Grid Z Limits sections are all the same as what was set for the original grid.
10. Click OK to create the grid. 

Updated November 2021