CPM vs CPC: compare equivalent advertising costs
Effective CPM = CPC × CTR as a fraction × 1,000. A CPC of 0.20 at a 1% CTR corresponds to an effective CPM of 2.00. Equivalent cost does not imply equivalent traffic quality.
CPM vs CPC: compare equivalent advertising costs
| Assumed CTR | CPC (currency units) | Clicks per 1,000 impressions | Effective CPM (currency units) |
|---|---|---|---|
| 0.10% | 0.20 | 1 | 0.20 |
| 0.50% | 0.20 | 5 | 1.00 |
| 1.00% | 0.20 | 10 | 2.00 |
| 2.00% | 0.20 | 20 | 4.00 |
| 5.00% | 0.20 | 50 | 10.00 |
Formula & method
eCPM = CPC × (CTR% ÷ 100) × 1,000
Equivalent CPC = CPM ÷ (1,000 × CTR fraction)Use actual cost and clicks when evaluating a completed campaign. For planning, choose a CTR assumption and label it as an assumption. Multiplying the click price by expected clicks per thousand impressions puts CPC and CPM on the same cost scale. Keep the impression definition consistent: served impressions and viewable impressions are different denominators.
The same eCPM can produce different conversion value. Compare the device, placement, audience and measurement window before treating two offers as alternatives.
Worked example
A 0.20 CPC campaign at 0.5% CTR costs 1.00 per thousand impressions. At 2% CTR it costs 4.00 per thousand. The higher CTR is more expensive per impression under CPC billing, even if each click costs the same.
What can change the answer
CTR must be greater than zero when deriving equivalent CPC. The table uses hypothetical rates, not bids or CPMs offered by an ad network.
Sources & definitions
- Google Ads: average cost per click definition
- Google Ads: cost per thousand impressions definition
- Google Ads: clickthrough rate definition
Method checked:
Continue with a related task
CPM Calculator
CPM equals advertising spend divided by impressions, multiplied by 1,000. A spend of 1,200 for 400,000 impressions gives a CPM of 3 in the same currency.
CPC Calculator
Average CPC equals advertising spend divided by recorded clicks. Spending 150 for 300 clicks gives an average CPC of 0.50.
Percentage Calculator
Calculate a percentage of a base value and the value after that percentage is added or removed. Enter a negative base only when it makes sense for your task.
CPA Calculator
CPA equals advertising spend divided by tracked actions. A campaign costing 600 with 24 qualifying actions has an average CPA of 25.