The calculation timer for these buttons is controlled by your FastExcel settings

The Excel Calculation Settings Tab also contains buttons to request various types of calculation. FastExcel will show the time taken by the calculation if the calculation timer for buttons is switched on.

By default MixMode sheets are calculated if Mixed Mode Full Calculate is on

Calculate Full Rebuild rebuilds the dependency trees and then fully calculates all formulas in all open workbooks. This option is only available from Excel 2002 onwards.

By default MixMode sheets are calculated if Mixed Mode Full Calculate is on

Calculate Full fully calculates all formulas in all open workbooks.

Recalculation is the default Excel calculation process. Only changed cells and formulas dependent on changed cells are calculated

Recalculate recalculates all formulas in all open workbooks that have been changed or are volatile, or are dependent on a cell that has been changed or recalculated.
By default MixMode sheets are calculated if calculation mode is Manual and Mixed Mode Manual is on.

Sheet Calculate re calculates the selected Sheets assuming that all precedent worksheets and linked workbooks have been correctly calculated.

Recalculate Sheet recalculates all formulas on each selected sheet that have been changed or are volatile or are dependent on a cell on the selected sheet that has been changed or recalculated. By default MixMode sheets are calculated if Mixed Mode Selected Sheets is on.

Full Calculate Sheet calculates every formula on the selected Sheets assuming that all precedent worksheets and linked workbooks have been correctly calculated.

Full Calculate Sheet calculates all formulas on each selected sheet.
By default MixMode sheets are calculated if Mixed Mode Selected Sheets is on.

Use FastExcel Calculation Control->FastExcel Settings to choose between the 2 available Range Calculate methods (with or without dependencies internal to the selected range) and the number of Range Calculate trials (default 3). Range Calculate then shows the median time of all the trials

Range Calculate calculates the currently selected range of cells.
If more than one Area is selected; each Area is calculated left-to-right and top-to-bottom, in the sequence that the areas were selected.
If more than one worksheet is selected then only the selected range on the active worksheet is calculated.
If one or more of the selected cells is part of a multi-cell array formula then all the cells in the array formula will be included in the calculation.
If Calculation is set to Automatic both the time taken to calculate the range in Manual mode and the workbook recalculation time are shown.

Recalculates both MixMode and ordinary sheets.

MixMode Recalc is similar to Recalc (F9), except that the recalculation also includes all Mixed Mode sheets.