The most significant region of the KISSsoft workspace is occupied by input for the calculation. In this region all the data for a given calculation must be defined. Depending upon the complexity of a calculation, the input window may be divided into several tabs. In most cases a single side is sufficient to carry out the calculation. Every input window uses the same control elements which will be described now in greater detail.

As a rule, for each value input field there is the variable name, symbol, the editing field, and unit. If the editing field is greyed out then the variable can not be edited and will be determined by the calculation. Behind each input field there can be one or more of the following buttons:

- Setting the Check-Button fixes the entered value
- Setting the Radio-Button you select which of the values in a group will be calculated and which will be fixed
- The Size-Button calculates an appropriate suggestion for the value
- The Convert-Button recalculates the value from depending data
- The Plus-Button can be used to input further data related to the value
- The Info-Button shows appropriate information in the information window (see 1.2.6)

In some modules the data is displayed or entered in a table. Double clicking on the end tab to the left of a row selects a complete entry, while the data in a single cell can be edited by double clicking on the cell. Tables often have extra information as Tool Tips (see 1.6). The following buttons are as a rule provided with tables to input data:

- The Add-Button joins a new line to the table
- The Remove-Button removes a selected row from the table
- The Clear-Button deletes all entries in the table

In KISSsoft the units of the value input field (see 1.3.1) and in the tables (see 1.3.2) can be changed. To do this, click on the unit with the right mouse button. A context menu is opened which contains all possible units for this value. If a different unit to that currently used is selected, then KISSsoft converts the value in the input field to the appropriate value.

In order to toggle the default unit between metric and imperial use the main menu option Extras ⇒ System of Units.

In some cases it is practical to define a value in terms of a small mathematical expression. A formula editor is opened by clicking on the edit filed using the right mouse button. A formula can be defined using the four basic operations +, -, * and ∕. Additionally, all functions that are supported by the report generator can be used (see Tables 5.2). Confirm the formula with the Enter-Key (sometimes called ’Carriage Return’-Key) and the formula will be evaluated. The formula itself will be lost: if the formula editor is again opened the calculated value is seen and not the original formula.

For input fields which show an angle a dialog appears instead of the formula editor to input the value in Degrees, Minutes and Seconds.