No. You can't create a text box or edit box without it being connected to a field.
Actually, you can by using a variable as a <<$MergeVariable>> on your layout and setting up a conditional format expression with the Let function to assign it a value. Whether it is worth it or not, is up to you.
I learned this trick from LaRetta here in the forum:
Add some layout text to an out of the way area on your layout such as "I declare variables".
Give it this conditional format expression:
Let ( $layoutDisplayVariable = /* Put your calculation here */ ; True )
Select a font size of 500 to make this layout text invisible when you enter browse mode.
Now put the text: <<$LayoutDisplayVariable>> on your layout and it will display your calculated result without having to add a calculation field to a table.
Note: having worked with Visual Basic and Visual Basic for Applications, I'm familiar with forms where you can create objects on the form that have a calculated datasource built right in as part of the form's design. I've come to realize that this is an "advantage" that has a few cons along with the Pros so I advise looking before you leap into such methods.
While keeping your table schemas to a minimum number of defined fields is a good thing in general, when you place such a layout specific calculation on your layout, the calculation is specific to that layout and that layout's current record. If it turns out you need this on multiple layouts, you can copy and paste it several different layouts, but if you then determine that this calculation needs to be modified, you have to carefully make identical changes to each layout where the calcualtion is used. That can be another round of copy and pasting in many cases, but it is still a more complex process with an increased chance of inadvertantly creating an error when compared to going to one table and modifying it's defined calculation. This also is then a calculated value that you cannot use for relationships or for which you can specify find criteria.
Also, given issues that Filemaker 12 is having with conditional formatting (greatly improved with the v02 update), I don't know how much "faster" it really is to use this method in that version of FileMaker.
Actually, you previously gave me this suggestion through a prior posting and I have successfully used it in my database. I was only trying to determine if FMP allows for a way to enter a calculation directly into a text box or blank edit box that you place on your layout as this could save some time. I know I was able to do this using Microsoft Access. Apparently, it appears that this is not possible with FMP. Your suggestion does make for a great workaround that I have used successfully. Thanks again.