Click-through rate is not something a seller publishes on a rate card — it depends on the creative, the audience and the placement, not the price. There is nothing here to seed from this directory's own rates; the calculator still works from whatever numbers are typed in.
CTR (click-through rate) is the share of impressions that turn into a click, shown as a percentage. It is not a price — no seller publishes a CTR on a rate card — it is a measure of how well an ad and its placement perform together, and it is what a buyer plugs into a CPM to work out the CPC they can expect to pay in practice.
A placement serves 250,000 impressions and receives 1,250 clicks. CTR = (1,250 ÷ 250,000) × 100 = 0.5%. That 0.5% is what turns a $6 CPM into a roughly $1.20 CPC once the campaign is running.
It depends entirely on the format and placement — a search ad, a banner and a newsletter link have different baselines, and this directory does not publish CTR benchmarks because sellers don't either. Treat it as something to measure on your own campaign, not a number to shop for.
Because it is the bridge between the two prices. A CPM tells you what reach costs; CTR tells you how much of that reach turns into traffic, which is what a CPC-minded buyer actually wants to know before comparing sellers.
Only loosely, and only against your own past results on that same seller — CTR moves with the creative and the audience as much as with the placement, so a single figure from one campaign is not a rate to compare sellers by.