How to track form abandonment.

Started and sent is the easy part, and GA4 gives you that. To find the field people quit on, something has to note the last field touched when a person leaves. You can write that yourself in a few lines, use a form analytics vendor, or use a tool that does it for you. Whatever you pick, record which field, never what was typed.

• First interaction

  is when GA4's form_start event fires: the first time a person interacts with a form in a session. That counts people who started. It does not say how far they got. Google Analytics Help

• 3 details

  come with form_start: a form ID, a form name and the page the form sends to. A field name is not among them, so GA4's built-in form events cannot say which field was last. Google Analytics Help

• Custom dimensions

  are needed before those details show in your reports. Google's page says you can only use the parameters in your reports if you create custom dimensions for them. Google Analytics Help

• 2015

  is when Simo Ahava published the classic Tag Manager recipe for form abandonment. He says it is built around a very simple, basic form, and that dynamic forms may not work. Simo Ahava's blog

• About 64 KiB

  is the most sendBeacon can carry, which is plenty for a field name and a count. MDN says the most reliable moment to send is when the page is hidden, because unload and beforeunload often never fire, especially on mobile. MDN Web Docs

• Free forever

  is how Microsoft describes Clarity, which records sessions so you can watch visits one at a time. Microsoft Learn

1. 01GA4 tells you a form was started and sent, not where it stopped

   On a plain HTML form, GA4's enhanced measurement can record form_start and form_submit with no code. Started minus sent is your drop-off, and that is a useful first number. But the field is not in either event, and the details only reach your reports once you set up custom dimensions. Google's page lists no abandon event. Google Analytics Help

   TRY THISSwitch on form interactions in GA4 enhanced measurement and read started against sent for a week. That tells you whether a form leaks at all.

2. 02A Tag Manager listener gets you to abandon, with more setup

   Ahava's recipe watches for a person leaving the page with a form touched and unsent, then sends an event. It is the usual answer to how to do form abandonment tracking in Google Analytics. It is from 2015, so the event setup needs adapting to GA4, and he says it suits simple forms. Simo Ahava's blog

   TRY THISUse it if you already live in Tag Manager and the form is plain. Name the event after the form, and send the name of the last field touched as a parameter, not its value.

3. 03Your own script is a few lines, and you own the privacy

   Listen for focus on each field and remember the last one. When the page is hidden, send that name with sendBeacon, unless the form was sent. Use visibilitychange for the hiding, not unload, which MDN calls unreliable. Send the field's name and its position. Never read its value. MDN Web Docs

   TRY THISStart with the one form you care about most. Send field names to your own endpoint or to a GA4 event, and read the count per field after a few dozen abandons.

4. 04Recordings show you one person at a time

   Microsoft Clarity is free and records sessions, so you can watch someone stop at the phone field. That is good for seeing why. It is slow for counting, because you watch visits one by one to learn how many did the same. Clarity masks what people type into input boxes in every mode, and Microsoft says that cannot be changed. Microsoft Learn

   TRY THISUse recordings to confirm a field you already suspect. Filter to visits on the form page and watch five.

5. 05Form analytics vendors count it for you, and cost money

   Zuko describes its product as form-level behaviour insights and abandonment tracking, with data on each field. It is built for this one job and goes deeper than the free routes above. Check its page for what it costs and what it stores. Zuko Analytics

   TRY THISWorth a look if the form is the business: a lead form, a loan application, a checkout. Ask any vendor what it does with typed values before you install it.

6. 06Hotjar is now part of Contentsquare

   Ahava's 2015 article pointed readers to Hotjar for form problems. Hotjar's page now says Hotjar is Contentsquare, and lists heatmaps, recordings and surveys, with attention maps, funnels and error monitoring on the free plan. Field-by-field form counts are not on that list. Hotjar

   TRY THISIf field-level drop-off is why you looked at Hotjar, ask Contentsquare whether your plan includes it before you rely on it, or use one of the routes above.