Create PDF Form & Detect Fields Automatically
Create fillable PDF forms, detect fields, add calculations
Create fillable PDF forms, detect fields, add calculations
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Add text, checkbox, radio and dropdown input fields
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Remove the password from an encrypted PDF first. The whole file is rewritten, so any existing digital signature becomes invalid. Keep the original and check the result.
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About Create PDF Form & Detect Fields Automatically
A form exported from Word is just lines and boxes drawn on a page: no viewer can type into it. This tool places AcroForm fields (text, checkbox, radio, dropdown, list box) on top so the PDF becomes fillable in Acrobat Reader, Preview, or a browser.
It has four tabs: drawing fields by hand, detecting underline and box candidates automatically, fixing the Tab-key order, and adding a quantity × price = total calculation with required-field warnings.
Field names become your column headers
Values in an AcroForm are stored against field names. When you later collect fifty returned forms, "FullName" and "Phone" turn into spreadsheet columns, so short, unambiguous names pay off. Radio buttons that share a name form one group, and each button needs a different export value (say, Yes and No) for only one to stay selected. Periods are rejected because PDF uses them to separate parent and child names in the field hierarchy.
Default values in Korean or other non-Latin scripts are drawn with an embedded, subset Noto Sans KR. Characters the recipient types later are drawn with the viewer's own font, so if that looks wrong in some viewers, turn on full font embedding (about 1 MB extra).
What detection finds, and what it misses
Detection reads vector lines only. A horizontal rule at least 20 pt long is an underline candidate. A closed rectangle 6–26 pt on each side with an aspect ratio within 1.5 is a checkbox; one at least 30 pt wide, at least twice as wide as tall and no taller than 60 pt is a text box. Text position is ignored, so decorative dividers show up and you deselect them. Tilted lines and image-only scans produce nothing.
How tab order and calculations actually work
PDF has no dedicated tab-order list. The order tab rewrites each page's annotation array (/Annots) in your sequence and sets /Tabs to row order (/R). Auto-sort reads top to bottom, treating fields within 8 pt of height as one row, then left to right.
The calculation tab attaches a Calculate script to the total field and registers it in the document's calculation order (/CO). If subtotals feed a grand total, register the subtotal rules first. Chrome, Edge and Firefox built-in viewers do not run form JavaScript, so test in Acrobat Reader or Foxit.
Field size and length limits
Leave the font size empty and the viewer scales text to the field height. A single-line field shorter than about 1.5 times its font size tends to clip descenders. Turn on multiline for addresses and comments, otherwise Enter does nothing.
A maximum length suits fields with a fixed format, such as a 5-digit ZIP code or a 10-digit US phone number, and stops obvious typos. If a default value is longer than the limit, the tool reports it before building the form.
Worked examples
An invoice total with thousands commas
- Input
Qty 3, Unit price "1,200.00" (with a thousands comma), Total = Qty × Price- Output
Total 3600
The calculation script drops currency symbols and thousands separators before reading the number, so "1,200.00" and "$1,200" both count as 1200. When a value has both a comma and a point, the last one is the decimal mark. A value that can't be read as a number counts as 0.
How to use it
- Open the PDF and draw fields, or pick candidates in the detection tab.
- Set names, defaults and required flags, then adjust tab order and calculations if needed.
- Open the saved file in Acrobat Reader and test typing, tabbing and totals.
Frequently asked questions
Can I edit fields that already exist?
Existing fields can be kept or deleted only. Delete one and redraw it with the same name; any script it carried is not copied over.
Can the calculation tab add or divide?
Only a multiply-two-fields rule is available. A grand total that sums several fields needs Acrobat's own field calculation settings.
The required-field warning did not appear.
The validation script runs when a value is committed, i.e. when the user leaves the field. A field that was never clicked can be left empty without a warning.
Sources
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