How do I convert a CPM bid into an expected CPC?

Divide the CPM by the number of clicks a thousand impressions will produce. At a 0.1% CTR, a thousand impressions yield one click, so the CPC equals the CPM. At 0.2% it is half the CPM; at 0.05% it is double.

What CPM should I bid to hit a target CPC?

Multiply the target CPC by your expected CTR, then by 10. A $1.50 CPC goal at an expected 0.08% CTR implies a CPM of about $1.20. Treat that as a ceiling rather than a plan, since the CTR assumption is the fragile part.

Why is my CPC different in the DSP and the client's analytics?

Analytics platforms count sessions that arrived, not clicks that were registered. Redirect drop-off, ad blockers and users leaving before the page loads all mean landing-page sessions come in below recorded clicks, so the analytics-derived CPC runs higher.

CPC Calculator

Calculate cost per click from spend and clicks. The arithmetic is simple; the useful part is knowing that in programmatic you do not buy clicks at all — you bid a CPM and receive a CPC, which means a CPC target is really a CPM bid plus an assumption about click-through rate.

Total spend

Clicks

CPC

$—

Enter both figures to calculate.

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Formula

CPC = Total Spend ÷ Clicks

Spend divided by clicks. In programmatic the relationship worth remembering runs the other way: CPC = CPM ÷ (CTR × 10), because a CPM buys a thousand impressions and CTR decides how many clicks those produce.

CPC is an outcome, not a bid

In an open-auction programmatic buy you submit CPM bids. The CPC you report afterwards is whatever those impressions happened to produce. That makes a client's CPC goal a joint constraint on two things you control differently: the CPM you are willing to pay, and the click-through rate your creative and placements achieve. A $2.00 CPM at a 0.10% CTR gives a $2.00 CPC. Hold the CPM and let CTR fall to 0.05%, and the CPC doubles to $4.00 with nothing else having changed.

Why CPC goals fail late in a flight

CTR usually drifts downward across a flight as frequency accumulates and the most responsive audience is exhausted. A campaign hitting its CPC goal comfortably in week one can miss it in week four at an unchanged CPM. If you are held to a CPC target, watch the CTR trend rather than the CPC itself — CTR moves first, and by the time the CPC has broken the goal you have already bought the impressions that broke it.

Frequently asked questions

How do I convert a CPM bid into an expected CPC?: Divide the CPM by the number of clicks a thousand impressions will produce. At a 0.1% CTR, a thousand impressions yield one click, so the CPC equals the CPM. At 0.2% it is half the CPM; at 0.05% it is double.
What CPM should I bid to hit a target CPC?: Multiply the target CPC by your expected CTR, then by 10. A $1.50 CPC goal at an expected 0.08% CTR implies a CPM of about $1.20. Treat that as a ceiling rather than a plan, since the CTR assumption is the fragile part.
Why is my CPC different in the DSP and the client's analytics?: Analytics platforms count sessions that arrived, not clicks that were registered. Redirect drop-off, ad blockers and users leaving before the page loads all mean landing-page sessions come in below recorded clicks, so the analytics-derived CPC runs higher.