How prefilled fields work
When somebody taps an ad that uses a Meta instant form, the form opens inside Facebook or Instagram instead of loading your website. Meta already holds the name, email address and phone number attached to that profile, so it drops those values into the matching fields before the person reads a word. All they have to do is glance at the details and press submit.
Only the standard contact fields behave this way. Anything you add yourself — a budget range, a preferred date, a district, a question about what they actually need — opens empty and has to be typed or tapped. Prefilled values are editable, so a person can correct an old email address before submitting, but very few take the trouble.
Why prefilled fields matter
They are the single biggest reason an instant form converts more readily than the same form on a landing page. There is no page load, no keyboard, no switching apps. On a slow mobile connection, which is how most people in Nepal meet your ads, that difference is the whole conversion.
They also quietly decide what sort of lead reaches your inbox. A form built entirely from prefilled fields takes a second to finish, so plenty of people complete it out of idle curiosity as well as genuine interest. And the address sitting in the field is whatever the person typed when they first opened their Facebook account, which may be years old, may belong to a phone they have replaced, or may be an inbox they never open. Prefilled is not the same as verified.
Common mistakes with prefilled fields
The commonest is treating the returned data as confirmed contact details and blaming the campaign when nobody answers. A dead number is not a fake lead; it is a stale profile field that nobody was ever asked to check.
The second is stripping out every custom question so the form fills itself completely. Completion goes up, cost per lead goes down, and the sales team quietly stops calling because too few of the enquiries are real. If you judge Meta lead generation ads on cost per lead alone, this looks like an improvement right up until the month’s sales are counted.
How to act on it
Start from the channel you will genuinely use to follow up. If your team rings people, make the phone field the one you draw attention to, and add a short line asking the person to check the number before submitting. If you email, do the same for the address.
Then add at least one custom question that a casual tapper will not bother answering — the service they want, the timeline, the city. It costs you some completions and buys you leads a salesperson is willing to phone. Preview the form on a real handset before launch, because a field that looks fine in the builder can sit below the fold on a small screen, and read the returned data weekly to see how many prefilled numbers actually connect.