How to Fill Out a PDF Form (Fillable, Flat or Scanned)
Published by PDFToolz · Updated · Technical references listed below
To fill out a PDF form, open it in your browser or a PDF app, click each field and type your answer, then save or download a copy. If you can't click into the blanks, the form is flat, so place text on top of the page with a text tool instead.
Most problems, such as fields that won't take typing or answers that vanish after saving, come down to the type of form you have. This guide shows how to tell the types apart, fill each one on a computer or phone, sign it, lock your answers and fix common errors. The PDFToolz form tools run in your browser, so your form is never uploaded.
How to fill out a PDF form, step by step
These steps work for any fillable form in Chrome, Edge, Firefox, Adobe Acrobat Reader, macOS Preview or PDFToolz Fill PDF Form.
- Open the PDF in your browser or a PDF app.
- Click the first blank. If a text cursor appears, type your answer.
- Press Tab to move to the next field. Tick checkboxes and pick options from dropdowns.
- Add your signature if the form asks for one.
- Save or download a copy, then reopen it and check every answer is still there.
- If you can't click into the blanks, the form is flat. Add text on top of the page instead, as shown further down.
Check if the form is fillable
A fillable form has interactive fields, such as text boxes, checkboxes, radio buttons and dropdowns, defined by the AcroForm structure in the PDF standard (ISO 32000). Each field stores its own value, so you click and type. A flat form is only a picture of a form, often a scan or a file exported without fields, so you place text on top of the page.
A third, rarer kind is the XFA form, an older Adobe format still used by some government and company forms. It looks fillable but only works properly in Adobe's desktop software. See the section on common problems below.
- Click where an answer goes. If a text cursor appears and you can type, the field is fillable.
- Press Tab. In a fillable form, focus jumps to the next field, and many viewers highlight the fields.
- Try to select a word. If no text can be selected, the page is probably a scanned image, which means a flat form.
- Open it in PDFToolz Fill PDF Form. If the tool says the PDF has no fillable form fields, treat it as a flat form.
How to fill out a PDF form online with PDFToolz
PDFToolz Fill PDF Form runs in your browser. The file is processed on your device and never uploaded, which matters for forms full of personal details. It works on any computer or phone, with no account or install.
The tool opens the form full screen with its fields live on the page, so you click a field and type. The Form fields tab beside the page also lists every text field, checkbox, radio group and dropdown, with a count of how many are filled. Names come from the form's author, so they range from clear ('Last name') to cryptic ('Text12'). Click a name to jump to its field on the page.
- Open Fill PDF Form and select your PDF.
- Type your answers and set the checkboxes and choices. Add a signature or date with the tools on the left if the form needs one.
- Press Download, then pick Flatten (lock answers) to fix the answers into the page, or Keep fields editable if someone still needs to change them.
- Save the file. Its name ends in -filled.
Fill a PDF form in your browser, Acrobat Reader or Preview
Every mainstream PDF app can fill a standard fillable form. They differ in how reliably they save your answers and how they handle forms with calculations, scripts or XFA. Whatever app you use, save a copy, close it and reopen it before sending. If the answers are still there, the save worked.
- In Chrome and Edge, open the PDF in the browser, click into the fields and type, then use the viewer's download or save button to keep a copy with your answers.
- Firefox's built-in viewer fills and saves standard fillable forms the same way.
- Adobe Acrobat Reader is free and the safest choice for complex, calculated and XFA forms. For flat forms, its Fill & Sign tools add text and a signature anywhere on the page.
- In macOS Preview, click into a field, type, then save. For a flat form, show the Markup toolbar and use its Text tool to add a text box you can drag into place.
How to fill out a PDF form on iPhone or Android
Phones handle fillable forms well. The small screen is the main problem. Zoom in before tapping so the right field gets focus, and reread each answer, because autocorrect can change names and codes.
On iPhone and iPad, open the PDF from Files or Mail and tap a field to type. For a flat form, open Markup (the pen icon) and use its add text option. Markup also has a signature option. On Android, recent versions of the Google Drive PDF viewer fill many fillable forms, and the free Adobe Acrobat Reader app handles fillable and flat forms. PDFToolz also runs in the mobile browser with nothing to install.
If a form acts oddly on a phone, with missing fields, a 'Please wait' message or dropdowns that won't open, it is probably an XFA form or relies on scripts that mobile apps skip. Finish it on a computer.
How to fill in blanks on a PDF that isn't fillable
A flat or scanned form has no fields, so you add text on top of the page. PDFToolz Edit / Annotate PDF opens each page full size and lets you place text exactly on the blanks.
Text boxes wrap, so an address can go in one box. A size of about 10 to 12 usually matches printed form text. Until you download, every box can be moved, resized and restyled, so line answers up with the blanks before you save.
- Open Edit / Annotate PDF, select the form and pick the Text tool.
- Click the page where an answer belongs and type. Set the font, size and colour in the style bar. Use the page thumbnails for multi-page forms.
- Tick a checkbox with the Check mark or Cross tool.
- If something lands in the wrong place, drag it with the Select tool, or undo.
- Press Download and save the filled PDF.
Sign the form, then lock your answers
PDFToolz eSign PDF lets you draw your signature, type your name in a handwriting-style font or upload a PNG or JPG of your signature, then click the page to place it. Place it again on as many pages as you need, and resize it by dragging its corners. The signature is fixed into the page as an image when you download. This is an electronic signature, not a certificate-based digital signature. That is fine for most everyday forms, but follow the recipient's method if they require a digital one.
Flattening turns filled fields into normal page content, so the answers look the same in every viewer and can't be changed through the form. If you kept fields editable, run the finished file through Flatten PDF. Form fields only fixes the answers into the page and keeps links and comments. Forms + annotations also removes links, comments and stamps. Keep an unflattened copy in case you need to fix an answer.
- Fill, then sign, then flatten. Or pick Flatten (lock answers) while filling and sign afterwards.
- Never flatten a file that already has a certificate-based digital signature. Rewriting the file invalidates it.
- Don't flatten if the recipient asked for the fillable form back, since their systems may read the field data.
Common problems and how to fix them
Most form failures come from a short list of causes.
- If answers disappear after saving, the fields were filled but the file was never saved, often because a preview was closed. Save or download a copy, then reopen it to check.
- If answers show in one app but are blank in another, the first app stored the values without redrawing how they look. Flatten the form before you send it.
- If you only see a 'Please wait' page, it is a dynamic XFA form. Download it and open it in the desktop version of Adobe Acrobat Reader, not a browser, phone app or Preview. Tools built on AcroForm, including PDFToolz, can't see fields in an XFA-only form.
- If letters show as odd symbols or empty boxes, the form's font may lack accented letters or non-Latin scripts. Try Acrobat Reader, or ask the issuer for a version that supports your language.
- If checkboxes or answers are missing on paper, some fields may be set not to print, and some viewers leave out form content when printing. Check the print preview, and flatten the file first if anything is missing.
- If text is cut off in a small box, the field shrinks or clips long text. Shorten it where allowed and check the flattened copy.
Checklist before you submit
Run through this list once the form is done. It catches the mistakes that most often get forms sent back.
- Every required field is filled, including those on later pages.
- Names, dates and ID numbers match your documents exactly, in the date format the form asks for.
- Checkboxes and choices are the ones you meant, and the signature and date are on the right page.
- You reopened the saved copy and every answer is still there.
- The file is flattened if answers must not change, or left fillable if the recipient asked for that.
- You kept a copy for your records.
Key takeaways
- ✓To fill out a PDF form, click each field, type your answer, then save a copy and reopen it to check.
- ✓Fillable forms have clickable fields. Flat or scanned forms need text placed on top of the page.
- ✓PDFToolz Fill PDF Form fills text fields, checkboxes, radio buttons and dropdowns in your browser without uploading the file.
- ✓For flat forms, place text with Edit / Annotate PDF, sign with eSign PDF and flatten so the answers can't be changed.
- ✓Forms stuck on a 'Please wait' message are XFA forms and need the desktop version of Adobe Acrobat Reader.
Tools for the job
Frequently asked questions
How do I fill out a PDF form?
Open the PDF in your browser, Adobe Acrobat Reader, Preview or PDFToolz Fill PDF Form. Click each field and type your answer, tick any checkboxes, then save or download a copy. If you can't click into the blanks, the form is flat, so add text on top of the page with a text tool.
How do I fill out a PDF form online for free?
Use PDFToolz Fill PDF Form. Select the PDF, type your answers, set the checkboxes and choices, then press Download to save the filled copy. It is free, needs no account and processes the file in your browser. If the form has no fields, use Edit / Annotate PDF to type on the page.
How do I fill in the blanks on a PDF that isn't fillable?
Place text on top of the page. In PDFToolz Edit / Annotate PDF, pick the Text tool, click where the blank is and type your answer. Drag the box to line it up. Acrobat Reader's Fill & Sign tools and the Markup text tool in Preview or on an iPhone do the same job.
Why won't my PDF form save my answers?
Usually the fields were filled but the file was never saved, for example because a browser or email preview was closed. Save or download a copy, then reopen it to check. If answers show in one app but not another, flatten the form before sending so the answers become part of the page.
Why does my PDF form only show a 'Please wait' message?
The file is a dynamic XFA form, an older Adobe format that browsers, Preview, phone apps and most online tools can't display. The message is a placeholder page. Download the file and open it in the desktop version of Adobe Acrobat Reader, which shows the real form so you can fill and save it.
Can I fill out a PDF form on my phone?
Yes. On iPhone, open the PDF from Files or Mail and tap the fields, or use Markup to add text to a flat form. On Android, the Google Drive PDF viewer and the Adobe Acrobat Reader app can fill many forms. PDFToolz also works in a mobile browser with no app to install.
Is it safe to fill out a PDF form online?
It depends on where the file goes. Many online PDF services upload your form to their servers, which is a risk for forms with ID numbers or health and financial details. PDFToolz processes the file in your browser, so the form and your answers never leave your device.
Related terms
Sources and further reading
- Fill in forms, Adobe Acrobat Reader from Adobe Acrobat Reader Help
- Fill and sign flat forms in Acrobat from Adobe Acrobat Help
- ISO 32000-2 (PDF 2.0) from PDF Association
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