CTR measures the effectiveness of an advertisement. It is calculated using the following formula that involves the number of clicks and impressions:
CTR = (Clicks/Impressions) x 100
A high CTR means that it attracts attention and get clicks often. A low CTR means the ad is under-performing and should be evaluated further. Other similar terms include: response rate, click-thru ratio.
Example
A 1.0% CTR means that for every 100 impressions, there is 1 click.
Monitoring CTR
You should measure each ad’s CTR regularly and make appropriate changes to improve its CTR. An ad with a low CTR should be modified, or even removed from the rotation. An evaluation should be performed when an advertisement gets at least 1,000 impressions. If this impression threshold is met and it still has a low CTR, less than 0.1%, it should be checked for the use of headings, hot spots, an appropriate call to action and other effectiveness factors.
Gross CTR
Gross CTR = (Gross Clicks / Gross Impressions) x 100
Unique CTR
Unique CTR = (Unique Clicks / Unique Impressions) x 100
