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Measurement and metrics

CTR (Click-Through Rate)

Also called Click-Through Rate, click rate, clickthrough rate, click percentage.

Short answer

CTR (Click-Through Rate) is the share of impressions that turn into clicks, calculated as clicks divided by impressions. CTR measures whether an ad, a link or a search result is relevant enough to be clicked.

Definition of CTR (Click-Through Rate).

CTR is the first link in every affiliate chain. Before anyone can convert, they have to click, and before anyone can click, they have to see something worth clicking. The figure therefore answers one question precisely: whether the message and the placement match what the recipient was doing.

The denominator is the difficult part. An impression means something different from channel to channel: a banner is counted as shown when it loads, a search result when it appears in the results list, a newsletter when it is delivered or opened, depending on who is measuring. Two CTR figures from two channels therefore do not measure the same thing, and the difference between them is not an insight.

CTR says nothing about what the click was worth. A headline that promises more than the page delivers raises CTR and lowers everything after it. That is why CTR is always read together with the conversion rate and EPC: CTR shows whether people click, the conversion rate whether the click was relevant, and EPC whether it was worth money.

How it is calculated

CTR = (number of clicks ÷ number of impressions) × 100

number of clicks
recorded clicks on the link or ad, after bots have been filtered out
number of impressions
the number of times the ad or link was shown – the definition must be the same in all figures you compare

Example

Impressions
40,000
Clicks
1,200
CTR
3.0 %

A CTR of 3 % means that 3 out of 100 who saw the placement clicked – and that 97 did not, which is often the more interesting figure.

CTR cannot be compared across channels

A text link in the middle of an article, where the reader is already researching a purchase, can sit well above a banner in the sidebar of the same page. That does not mean the banner is bad – it means the two placements measure two different situations.

The only comparison that holds is against yourself: same placement, same channel, same counting method, over time. Everything else is figures that look alike without being about the same thing.

CTR multiplied by the conversion rate

The figure that actually drives earnings is conversions per impression, and it is found by multiplying CTR by the conversion rate. A placement with a 5 % CTR and a 1 % conversion rate gives 0.05 % conversions per impression. One with a 2 % CTR and a 4 % conversion rate gives 0.08 % – in other words more, despite the lower CTR.

If you optimise for CTR alone, you move the loss one step further down the funnel instead of removing it.

How it goes wrong

  • 01

    Impressions are not counted the same way

    If one report uses delivered emails as the denominator and the other uses opened emails, the same campaign can have two very different CTR figures. Fix the definition before the figures are put side by side.

  • 02

    High CTR, low earnings

    Headlines that promise too much attract clicks from people who would not have bought. CTR rises, the conversion rate falls, and EPC falls most of all. The store sees a traffic source that does not work, and the affiliate loses the placement.

  • 03

    Bots inflate both figures

    Automated visits generate both impressions and clicks, but almost never purchases. Without bot filtering, CTR looks reasonable while the conversion rate falls inexplicably – and the fault lies in the data, not the content.

Frequently asked questions

How do you calculate CTR?

CTR is calculated as the number of clicks divided by the number of impressions, multiplied by 100. If a placement got 1,200 clicks on 40,000 impressions, the CTR is 3.0 %. Clicks should be counted after bots have been filtered out, and impressions must be counted the same way in all figures being compared.

What is a good CTR?

There is no figure that applies across channels, because an impression means something different in a banner, a search result and a newsletter. The useful yardstick is your own history on the same placement: a CTR is good when it is higher than last month’s in the same spot, measured the same way.

What is the difference between CTR and conversion rate?

CTR measures the share of impressions that become clicks. The conversion rate measures the share of clicks that become sales or leads. CTR has impressions in the denominator, the conversion rate has clicks. The two figures multiplied together give conversions per impression, which is the figure earnings follow.

Can CTR be over 100 %?

Not if clicks and impressions are measured on the same event. If it happens anyway, the two are being counted differently – for example when the same visitor clicks several times on a link that was only shown once, or when impressions are lost to blocking software while the clicks are still recorded.

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