How-to · Updated October 11, 2026
Work out how many call tracking numbers you need
Updated October 11, 2026
15 minutes
CallTrackingMetrics recommends one tracking number for every 20 unique daily visitors from each source; divide and round up. Take the count from Google Ads clicks that open the website, leaving out phone taps. At a few hundred clicks a month, 2 to 3 numbers is usually enough. Add one fixed number per offline source.
Before you start
- Read access to Google Ads, and to any other ad account whose visitors will see their own numbers.
- A list of your offline sources, such as print, signs, vehicles and directories, plus the number in your ads' call button. Each one gets its own fixed number.
Count the visitors each source sends
The rule works per source, so count each paid source on its own.
- In Google Ads, open Campaigns and set the date range to the last 30 days.
- Click the segment icon and choose Click type. Add up the clicks on the rows that open your website, such as Headline, Website and Sitelink. Leave out Mobile Clicks-to-Call, Lead form, Driving Directions and the location rows: Google counts a tap on the phone number in an ad as a click, but that caller never loads your website.
- Divide the total by 30 for website visitors a day. To size for busy days, segment by Time, then Day of the week, and divide your busiest weekday's clicks by the number of those weekdays in the range.
- Using Google Ads rather than analytics for a paid source is a judgment; CallTrackingMetrics suggests Google Analytics. Google Ads counts paid clicks whether or not analytics is installed or separates paid visitors. Google counts a click even when the person does not reach the site, so clicks may run above visits, which errs toward one number too many.
- Repeat for each other source that will show its own numbers, such as Microsoft Ads or social ads, from that platform's own click count.
Turn the counts into numbers
CallTrackingMetrics recommends one tracking number for every 20 unique daily visitors from each source.
- Divide each source's daily visitors by 20 and round up. As an example, 450 website clicks in 30 days is 15 a day, so the rule gives 1 number.
- Adding one or two numbers for busy days and returning visitors is a judgment, not the vendor's rule: the tool remembers which number each visitor saw and keeps showing it when they come back. At a few hundred clicks a month, 2 to 3 numbers is usually enough.
- Add one fixed number for each offline source, and one for the number in your ads' call button. Pool numbers are swapped in by the script on your website, so they never appear in the ad itself.
- If you buy through CallTrackingMetrics' Number Pools, enter the daily count for the traffic that pool tracks in Estimated Visitor Count; a pool takes one tracking source. The preset PPC Visitors source takes paid visitors from Google, Microsoft, Facebook and other ad platforms together, so add those platforms' counts. All Visitors also includes organic traffic, which Google Ads cannot count. With Enable automatic number pool management on, the default, it buys enough numbers for 99% accuracy; turn it off to set the count yourself, and it shows the accuracy that count gives.
A pool's size changes within 24 hours of a new visitor count, not at once.
Check it worked
After a month of calls, open Reports, then Accuracy Report, choose the date range and pick the source. CallTrackingMetrics marks a well-sized pool with Allocation looks good and says you typically want a likelihood score of at least 90% for each source.
A pool that is too small still records the calls. CallTrackingMetrics matches each call to the likeliest visitor, but scores may drop, so more calls are at risk of being credited to the wrong visit. If the minimum likelihood under Numbers, Tracking Code, Visitor Call Analytics has been raised from its default of 5%, low-scoring calls may get no visitor at all. Check the score on single calls through the bar chart icon in the Session Data column of the activity log.
When more numbers will not help
Numbers shown only to ad visitors get few or no calls while the ads are paused, since only returning visitors still see them, so a quiet pool during a pause is expected, not broken.
Calls from the call button in the ad never touch the pool, because the caller never loads the site. If those calls are missing, the fixed number in the call asset is the place to look, not the pool size.