Time to complete a goal or transaction using GTM and Google Analytics

Here is a quick overview of how to track the time needed for a user to finalize a desired activity inside a session using Google Tag Manager and Google Analytics. The example in this article is a simplified overview of various hits and methods on how we can achieve process tracking inside Google Analytics. By default Analytics measures Session length / duration and time on page which is quite challenging in this cases and rarely applicable thus one may be forced to use features like custom metrics and / or user timing hits.

Case – time from session start to lead generation form submit

A user starts a session and is expected to fill and submit a lead generation form. We would really like to know how long this process usually takes (not the entire multichannel / multi device experience in this case but just the in session experience).  The experience will be highly affected by previous experience with the site – so using some segments while analysing would come in quite handy.

The idea on how to fetch these values is quite simple. Drop a cookie once a session starts, or in some specific cases when an on site process starts (e.g. checkout) – where the cookie value will be the session / process start time. After the user has completed the process – successfully completed the desired action (we basically mimic Analytics goal behaviour – so it is either a destination or an event based trigger in GTM) we send a User timing hit or an event hit with a time type custom metric.


The procedure

What is needed:

1. Cookie tag – Custom HTML
On session start we set a session level cookie.

var d = new Date().getTime();
document.cookie = "sessionStart=" + d + "; path=/;";

Trigger – Pageview using a 1st party cookie variable sessionStart (so fire only if sessionStart is undefined).
Variable – 1st party cookie – sessionsStart ({{gtm sessionStart}}).

trigger first page in a session

 2. Google Analytics pageview tag – Template tag – Universal Analytics

This is a basic GA universal pageview tag yet I added a hitCallback inside ‘Fields to set’ to safely set a clientId as a custom dimension (user level – do not forget to dreate the custom dimension inside GA admin) in an additional event tag (ty Simo!) – this will fire a Google Analytics event tag only when the Pageview tag has fired successfully. so the setup looks like this:

universal analytics main pageview tag

Trigger – All pages (default trigger).
Variable – custom js variable which send a custom event via dataLayer push – this event is used for the Utility Event responsible for adding a custom dimension with clientId value.

check if ua pageview fired

function() {
return function(){dataLayer.push({'event': 'pageViewFired'});}

3. Google Analytics Event tag – Template tag – Universal Analytics

A simple event tag which only purpose is to set the Custom Dimension value of the users clientId (this is used to further analyse time for each process based on the client Id – some randomization could be utilized if a user is expected to have multiple conversions or even add a process end time as a custom dimension or use time dimensions in GA).

event tag set cid

Trigger – event equals pageViewFired.
Variable – use a custom JS variable which will fetch the clientId value.

function() {
return ga.getAll()[0].get('clientId');

4. Google Analytics User timing tag – Template tag – Universal Analytics

This is where we send info to GA that the process has successfully ended and pass the time value. So the setup looks like this:

user timing hit

Trigger – any which identifies the session has resulted in a goal completion. For this case I used a simple custom event – trackConversion – dataLayer.push({‘event’:’trackConversion’});

Calculation and variables – as you noticed a different variable is used for the custom metric and user timing value. The reason for this is that user timing hit requires a value in milliseconds and custom metrics in seconds. The calculation is pretty simple.  You need 2 variables:

User timing value

function (){
var endTime = new Date().getTime(); // this could easily be a separate variable
return endTime - {{gtm sessionStart}};

and Custom metric value

function (){
var endTime = new Date().getTime(); // this could easily be a separate variable
return (endTime - {{gtm sessionStart}})/1000;

And that’s basically it – one word of caution though user timing hits are prone to sampling so consider sending the timing info through events with CD and CM defined.

When you are done setting this up the example report could be something like this:

report example


Hope the article was useful and of course happy tracking!


Author bio

Zorin Radovančević

July 22, 2015 Google Analytics, Google Tag Manager

Senior Web Analytics implementation and planning specialist - all things related to Google Analytics, Google Tag Manager and Yandex Metrica.


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