Measurement Class:  This box lets you select the measurement class of the conversion you wish to make.  The options are Area, Basal Area (Forestry), Circular, Circular Area, dbh (Forestry), Energy/Work, Flow, Force, Length, Power, Pressure/Stress, Temperature, Time, Velocity, Volume, and Weight/Mass, plus any user-created classes that you have added.  Selecting a measurement class is not required, but it saves some time by refilling the FROM Unit and TO Unit boxes with only those units from that measurement class.  For example, if you choose the “Temperature”  measurement class, then you will only have to choose from the six Temperature measurement units when you click on the FROM and TO boxes rather than sorting through the complete set of 1,000+ units.

FROM Unit:  Here is where you select the unit you want to convert from.  If you click on this without selecting a Measurement Class first, you will see a list of over 1,000 units and you may have to spend a little time finding the one you want.   They are ordered alphabetically and you can type the first letter to take you to the general area.  Typing the first letter repeatedly will rotate you through all the units beginning with that letter.

TO Unit:  Here is where you select the unit you want to convert to.  As with the FROM units, you’ll probably find your unit faster if you select the Measurement Class first.

REVERSE Button:   In case you accidentally select the FROM and TO units backwards, the REVERSE button is a quick way to switch them.

CONVERT Button:  The CONVERT button executes the conversion.

CLEAR Button:  The CLEAR button clears out all the selected information and any numbers that have been typed into the INPUT VALUE textbox.

EXIT Button:  The EXIT button turns off Unit Converter.

DECIMAL vs. SCIENTIFIC NOTATION:  Here you can decide whether you want your output to be in Decimal Format or Scientific Notation.  If your converted value is 1,345 in Decimal, it will look like 1.345 e3 in Scientific Notation.   Unit Converter looks at the number style of your input value and how big or small your converted output value is and uses logic to predict the most appropriate output format, but you can always switch it if you like.

Adjust Number of Decimal Places:  You can adjust the number of decimal places for your output anywhere between 0 and 14 digits.  However, be aware that the conversion factors used for this program typically run to 7-8 significant figures, so precision and accuracy are unreliable beyond that point.  All conversions have been tested and should be accurate within that range.

Save Conversion as Default #1:  This button allows you to save the current FROM and TO Conversion units as Default Conversion #1.  Once you click this button, the current FROM and TO values will appear in the “USE DEFAULT CONVERSION #1” button and they will be there the next time you start Unit Converter.  This software saves a file called "conv_def.txt" in the same folder with Unit Converter which contains these default values.  If this file becomes corrupted somehow, you can reset it using the "Clear Defaults" menu item under the "File" menu.

Save Conversion as Default #2:  This button allows you to save the current FROM and TO Conversion units as Default Conversion #2.  Once you click this button, the current FROM and TO values will appear in the “USE DEFAULT CONVERSION #2” button and they will be there the next time you start Unit Converter.  This software saves a file called "conv_def.txt" in the same folder with Unit Converter which contains these default values.  If this file becomes corrupted somehow, you can reset it using the "Clear Defaults" menu item under the "File" menu.

Use Default Conversion #1:  Clicking this button will cause the default #1 TO and FROM measurement units to be automatically inserted into the TO and FROM boxes.  This saves a considerable amount of time if you use this conversion a lot.

Use Default Conversion #2:  Clicking this button will cause the default #2 TO and FROM measurement units to be automatically inserted into the TO and FROM boxes.  This saves a considerable amount of time if you use this conversion a lot.

One-To-One Conversion:  This information box gives one-to-one conversions of the TO and FROM  units you select.  For example, if you were interested in converting 100 acres to hectares (as in the above illustration), this One-to-One Conversion Box  would tell you that there are 2.471 acres per hectare and 0.404 hectares per acre.  The OUTPUT box would tell you that there are 40.47 hectares in 100 acres.  Notice that this box gives the one-to-one conversion out to several decimal places.  To make it more readable, I formatted it so that there were spaces every 3 digits past the decimal point, and commas every 3 spaces in front of the decimal point.

Numeric Keyboard:  Numbers can be entered either on your own keyboard or on this digital keyboard.  The +/- symbol allows you to change the sign of your input number at any point.   The E+ and E- symbols allow you to enter in scientific notation. The ß symbol is a backspace function and erases the last thing you typed.  The / symbol allows you to enter in fractional notation.  To enter whole units plus a fraction (i.e. "5 and 1/8"), separate the whole unit from the fraction by a space.  In other words, "5 and 1/8" should be entered as "5 [space] 1/8", or literally “5 1/8".  This would then convert to 5.125 before the unit conversion takes place.

Input Value to be Converted:  Here is where you enter the number of FROM units you want to convert.   These numbers can be entered as Decimal format, Scientific Notation or Fractions.  To enter scientific notation, use the letter "e" to indicate the exponent (as in "10 to the e power"), or use the E+ and E- symbols on the numeric keyboard.  To enter fractions, just use the "/" symbol to separate the numerator from the denominator.  The fraction will be converted to a decimal when you hit the Convert button, then the decimal value will be converted into your TO units.  For example, if you type "1/4" and hit the "Convert" button, "1/4" will change to "0.25" and the conversion will be carried out.  To enter whole units plus a fraction (i.e. "5 and 1/8"), separate the whole unit from the fraction by a space.  In other words, "5 and 1/8" should be entered as "5 [space] 1/8", or literally “5 1/8".  This would then convert to 5.125 before the unit conversion takes place. 

Output Converted Value:  When you hit the CONVERT button, Unit Converter puts the converted value in this box.

Menu Items:

	File: Clear:  Clears out all the selected information and any numbers that have been typed into the INPUT VALUE textbox.  This is the same as the CLEAR button. Clear Defaults:  Erases the two sets of default conversion units, leaving them as “Undefined”.  This will also disable the two “Use Default Value” buttons until new defaults have been saved.  If the file containing the default values (conv_def.txt) becomes corrupted somehow, this menu item will clear it out. Print:  Prints the current conversion, plus the measurement class, definitions of each item and one-to-one conversions of each item. Exit:  Turns off Unit Converter.  This is the same as the EXIT button.
	Edit: Cut:  Copies the selected to the clipboard where it can be pasted into other programs,  then deletes the selected text.  As a shortcut, you can hit [Control]-X to use this function. Copy:  Copies the selected to the clipboard where it can be pasted into other programs,  but does not delete the selected text.  As a shortcut, you can hit [Control]-C to use this function. Copy Output:  Copies the Output converted value to the clipboard where it can be pasted into other programs. Paste to Input:  Takes whatever is currently saved in the Clipboard and pastes it into the Input box, provided the clipboard contains a number.  This is useful if you copy a long number from another source and don’t want to take any chances making a typo as you type it into Unit Converter.  If you manage to paste in a non-numeric value, Unit Converter will treat it as a single unit of that input unit.  As a shortcut, you can hit [Control]-V to use this function.
	Add Units: Primary Conversion Worksheet:  This option opens the Primary Conversion worksheet, which allows you to create brand new measurement classes and to create the primary conversions for those measurement classes.  Primary and Secondary conversions are explained in the Primary and Secondary Worksheet sections of this manual. Secondary Conversion Worksheet:  This option opens the Secondary Conversion worksheet, which allows you to add new measurement units to any of the measurement classes.  You must enter the conversion information to convert to one of the primary conversion units in that measurement class.  Primary and Secondary conversions are explained in the Primary and Secondary Worksheet sections of this manual. Review/Edit User Conversions:  This option opens the Review User Conversions window, which allows you to edit conversion data.  You can only edit units and conversions that you have added to the program.  All the original units and conversions are protected from alteration.  This window is explained more fully in the Review User Conversions section of this manual. Help with Adding Units:  This option opens a window describing how Unit Converter does conversions and explains the difference between Primary and Secondary conversions.  This information is also covered in this manual.
	Help: View Read Me:  This option opens a window describing a brief description of Unit Converter and the history of changes to it. Sources:  This option lists the sources for conversion information and definitions of units. Help with Adding Units:  This option opens a window describing how Unit Converter does conversions and explains the difference between Primary and Secondary conversions.  This information is also covered in this manual. Definitions Open Input Unit Definition Box:  This option opens a window containing a definition of the current Input (or FROM) unit.  The contents of the window will change as different input units are selected.  This window can be opened by right-clicking on the FROM unit text box, or by hitting [Control]-I. Open Output Unit Definition Box:  This option opens a window containing a definition of the current Output (or TO) unit.  The contents of the window will change as different output units are selected.  This window can be opened by right-clicking on the TO unit text box, or by hitting [Control]-O. General Definition Box:  This window opens a general definition window that is not dependent on the current Input or Output units.  As a shortcut, this window can be opened by hitting [Control]-G. About Unit Converter:  This option opens a window containing information such as the current version number of Unit Converter, who it’s licensed to (or what day you are currently on in your 30-day trial), and the address of the author to report problems.  There are also buttons here to open the Read Me and Sources windows.